We are searching data for your request:
Upon completion, a link will appear to access the found materials.
Hearing from the National Geographic and the news about the discoveries of new species of plants/animals, I was wondering how can a person confirm when they have actually discovered a new species of plant or animal?
How can they identify with enough certainty that it is not one of the species that has been previously discovered (out of the umpteen varieties of species)? Is there some kind of official/international database of species for plants/animals they typically look up to to confirm it? Also, how is the process of naming of a new species decided and why does it end up being a Latin name?
Basically, you have to examine as much of the relevant 'material' (preserved museum specimens) of the proposed new species and its closest relatives, and compare the diagnostic characters of your proposed new species versus those of its presumed closest relatives to confirm it is actually distinct. For example, with snakes (my field), we use counts of head and body scales, relative distances between features, relative length of tail, hemipene morphology, and even colouration, to determine species.
When combined with genetic evidence of monophyly of the new species and adequate divergence from closest relatives, it becomes a very robust species description. Finally, names can be accepted or rejected by the ICZN based on existing names for proposed species, though it's a very confusing mess for most groups. I'd recommend checking out their website for more in-depth guidelines
Where do new species come from?
Since Charles Darwin and other scientists of the 19th Century drafted the first theories of evolution, biologists have studied and partly unveiled this mysterious process that has endowed Earth with the amazing diversity of creatures we witness today. Yet, we still don’t understand entirely the intricate mechanisms that drive the formation of new species, and it has only recently become clear that, given the right conditions, new species can appear quite rapidly.
For the first evolutionary biologists such as Darwin and Alfred Russell Wallace, the emergence of new species - speciation - was principally visible on a continental scale. They observed that populations separated over large distances and long periods of time had adapted differently to their environments and taken separate evolutionary paths. With the lack of tools or even knowledge of genetics, evolution was a process that could only be witnessed with the eyes. Darwin understood that the birds on several islands of the Galapagos looked similar to each other and to those of the American continent, yet showed several key differences, like the sizes of their beaks. This helped him develop the idea of species changing and adapting to new environments through natural selection. It was, however, much harder to explain how new species arose in the absence of geographical barriers and through forces different from natural selection.
The study of evolution took a gigantic step forward with the arrival of genetics and the advances that have been made since Gregor Mendel devised the first principles in the garden of the monastery where he grew his famous peas. Nowadays, thanks to the enormous progress in scientific technology, we can affordably sequence entire genomes in a matter of days, grow thousands of parallel cell-cultures in the laboratory and do even more insane things that were completely unimaginable fifteen years ago. We can now witness evolution on smaller and larger scales than Darwin and Wallace could with their naked eyes. It is now, more than ever, that we realise how ubiquitous and diverse evolution truly is.
As a graduate student at the Ludwig-Maximilians-Universität in Munich, I got the chance to study the process of speciation through a very interesting set of grasshopper species grouped under the genus name Chorthippus. These different species all look incredibly similar, making it practically impossible for biologists to distinguish them based on their appearances. To make the distinction even more challenging, the species co-exist in large areas of Europe, occurring side-by-side even in the very same meadows. Yet, taxonomists have classified them into separate species according to the distinctive mating songs of the males. More recent studies however, have questioned whether one could rightfully categorise Chorthippus grasshoppers into different species. First, researchers discovered that the species can mate and produce healthy hybrid offspring when forced to do so in the lab. If the animals were doing this in the wild, one could argue they were just a single species with many song variations. Secondly, phylogenetic research on the Chorthippus group showed that grasshoppers supposedly belonging to different species were genetically so closely related that it wasn’t possible to place them in different groups. Yet, this study was only based on a minute part of the gigantic grasshopper genome, turning it into the equivalent of looking at a single brush-stroke of an inmense, intricate and detailed painting.
The first meaning is the result of interbreeding between two animals or plants of different taxa.
Hybrids between different species within the same genus are sometimes known as interspecific hybrids or crosses.
Hybrids between different sub-species within a species are known as intra-specific hybrids.
Hybrids between different genera are sometimes known as intergeneric hybrids.
Extremely rare interfamilial hybrids have been known to occur (such as the guineafowl hybrids).
The second meaning of "hybrid" is crosses between populations, breeds or cultivars of a single species.
This second meaning is often used in plant and animal breeding.
An example of an intraspecific hybrid is a hybrid between a Bengal tiger and an Amur (Siberian) tiger.
Interspecific hybrids are bred by mating two species, normally from within the same genus.
The offspring display traits and characteristics of both parents.
The offspring of an interspecific cross very often are sterile, this hybrid sterility prevents the movement of genes from one species to the other, keeping both species distinct.
Sterility is often attributed to the different number of chromosomes the two species have, for example donkeys have 62 chromosomes, while horses have 64 chromosomes, and mules and hinnies have 63 chromosomes.
Mules, hinnies, and other normally sterile interspecific hybrids cannot produce viable gametes because the extra chromosome cannot make a homologous pair at meiosis, meiosis is disrupted, and viable sperm and eggs are not formed.
However, fertility in female mules has been reported with a donkey as the father.
Most often other mechanisms are used by plants and animals to keep gametic isolation and species distinction.
Species often have different mating or courtship patterns or behavours, the breeding seasons maybe distinct and even if mating does occur antigenic reactions to the sperm of other species prevent fertilization or embryo development.
The Lonicera fly is the first known animal species that resulted from natural hybridization.
Until the discovery of the Lonicera fly, this process was known to occur in nature only among plants.
Plants’ Reaction to Rain is Close to Panic, Study Shows
Complex chemical signals are triggered when water lands on a plant to help it prepare for the dangers of rain, according to a new study published in the Proceedings of the National Academy of Sciences.
Van Moerkercke et al made the surprising discovery that a plant’s reaction to rain is close to one of panic. Image credit: Anthony, Inspired Images.
In contrast to humans, plants cannot feel pain. However, so-called mechanical stimulation — rain, wind and physical impact from humans and animals — contributes to the activation of a plant’s defense system at a biochemical level. This in turn triggers a stress hormone that, among other things, can lead to the strengthening of a plant’s immune system.
“As to why plants would need to panic when it rains, strange as it sounds, rain is actually the leading cause of disease spreading between plants,” said University of Western Australia’s Professor Harvey Millar, co-author of the study.
“When a raindrop splashes across a leaf, tiny droplets of water ricochet in all directions. These droplets can contain bacteria, viruses, or fungal spores.”
“The sick leaves can act as a catapult and in turn spread smaller droplets with pathogens to plants several feet away. It is possible that the healthy plants close by want to protect themselves,” added study lead author Dr. Olivier Van Aken, a biologist at Lund University.
In lab experiments, Dr. Van Aken, Professor Millar and their colleagues used a common plant spray bottle set on a soft spray.
Arabidopsis thaliana plants were showered once from a distance of 6 inches (15 cm) after which the researchers noticed a chain reaction in the plant caused by a protein called Myc2.
“When Myc2 is activated, thousands of genes spring into action preparing the plant’s defenses,” Professor Millar explained.
“These warning signals travel from leaf to leaf and induce a range of protective effects.”
“Our results show that plants are very sensitive and do not need heavy rain to be affected and alerted at a biochemical level,” Dr. Van Aken said.
The findings also suggest that when it rains, the same signals spreading across leaves are transmitted to nearby plants through the air.
“One of the chemicals produced is a hormone called jasmonic acid that is used to send signals between plants,” Professor Millar said.
“If a plant’s neighbors have their defense mechanisms turned on, they are less likely to spread disease, so it’s in their best interest for plants to spread the warning to nearby plants.”
“When danger occurs, plants are not able to move out of the way so instead they rely on complex signaling systems to protect themselves.”
“It was clear plants had an intriguing relationship with water, with rain a major carrier of disease but also vital for a plant’s survival,” Professor Millar concluded.
Alex Van Moerkercke et al. A MYC2/MYC3/MYC4-dependent transcription factor network regulates water spray-responsive gene expression and jasmonate levels. PNAS, published online October 29, 2019 doi: 10.1073/pnas.1911758116
What a Newfound Kingdom Means for the Tree of Life
The tree of life just got another major branch. Researchers recently found a certain rare and mysterious microbe called a hemimastigote in a clump of Nova Scotian soil. Their subsequent analysis of its DNA revealed that it was neither animal, plant, fungus nor any recognized type of protozoan&mdashthat it in fact fell far outside any of the known large categories for classifying complex forms of life (eukaryotes). Instead, this flagella-waving oddball stands as the first member of its own &ldquosupra-kingdom&rdquo group, which probably peeled away from the other big branches of life at least a billion years ago.
&ldquoIt&rsquos the sort of result you hope to see once in a career,&rdquo said Alastair Simpson, a microbiologist at Dalhousie University who led the study.
Impressive as this finding about hemimastigotes is on its own, what matters more is that it&rsquos just the latest (and most profound) of a quietly and steadily growing number of major taxonomic additions. Researchers keep uncovering not just new species or classes but entirely new kingdoms of life&mdashraising questions about how they have stayed hidden for so long and how close we are to finding them all.
Yana Eglit is a Dalhousie graduate student dedicated to discovering novel lineages of the single-cell eukaryotes called protists. While hiking in Nova Scotia on a cold spring day in 2016, she fell back from her friends to scrape a few grams of dirt into a plastic tube. (Such impromptu soil sampling, she said, is &ldquoa professional hazard.&rdquo) Back in the lab, Eglit soaked her sample in water, and over the next month she periodically peeked at it through a microscope for signs of unusual life.
Late one evening, something odd in the sample caught her eye. An elongated cell radiating whiplike flagella was &ldquoawkwardly swimming, as though it didn&rsquot realize it had all these flagella that could help it move,&rdquo Eglit said. Under a more powerful scope, she saw it fit the description of a hemimastigote, a rare kind of protist that was notoriously hard to cultivate. The next morning, the lab was abuzz with excitement over the opportunity to describe and sequence the specimen. &ldquoWe dropped everything,&rdquo she recalled.
Hemimastigotes represent one of a handful of Rumsfeldian &ldquoknown unknown&rdquo protist lineages&mdashmoderately well-described groups whose positions on the tree of life are not precisely known because they are difficult to culture in a lab and sequence. Protistologists have used peculiarities of hemimastigotes&rsquo structure to infer their close relatives, but their guesses were &ldquo&lsquoshotgunned&rsquo all over the phylogeny,&rdquo Simpson said. Without molecular data, lineages like hemimastigotes remain orphans of unknown ancestry.
But a new method called single-cell transcriptomics has revolutionized such studies. It enables researchers to sequence large numbers of genes from just one cell. Gordon Lax, another graduate student in the Simpson lab and an expert on this method, explained that for hard-to-study organisms like hemimastigotes, single-cell transcriptomics can produce genetic data of a quality previously reserved for more abundant cells, making deeper genomic comparisons finally possible.
The team sequenced more than 300 genes, and Laura Eme, now a postdoctoral researcher at Uppsala University, modeled how those genes evolved to infer a classification for hemimastigotes. &ldquoWe were fully expecting them to fall within one of the existing supergroups,&rdquo she explained. Lab members were instead stunned to find that hemimastigotes fit nowhere on the tree. They represented their own distinct lineage apart from the other half-dozen super groups.
To understand how evolutionarily distinct the hemimastigote lineage is, imagine the eukaryotic tree splayed out before you on the ground as a narrowing set of paths, which begin with places for all living groups of eukaryotes near your toes and converge far in the distance at our common ancestor. Starting at our mammalian tip, walk down the path and back into history, past the fork where our lineage diverged from reptiles and birds, past the turnoffs for fishes, for starfish and for insects, and then farther still, beyond the split that separates us from fungi. If you turn around and look back, all the diverse organisms you passed fall within just one of the six eukaryote supergroups. Hemimastigotes are still up ahead, in a supergroup of their own, on a path that nothing else occupies.
Fabien Burki, a biologist at Uppsala University in Sweden who wasn&rsquot involved in this study, was happy to see this result, but not entirely surprised. &ldquoIt&rsquos a bit like searching for life on other planets,&rdquo he said. &ldquoWhen we finally find it, I don&rsquot think we will be very surprised, but it will be a huge discovery.&rdquo
Burki, Simpson, Eglit and many others also think we have much more of the tree of life to uncover, largely because of how quickly it&rsquos changing. &ldquoThe tree of life is being reshaped by new data. It is really quite different than even what it was 15 or 20 years ago,&rdquo Burki said. &ldquoWe&rsquore seeing a tree with many more branches than we thought.&rdquo
Finding a lineage as distinct as hemimastigotes is still relatively rare. But if you go down a level or two on the hierarchy, to the mere kingdom level&mdashthe one that encompasses, say, all animals&mdashyou find that new major lineages are popping up about once a year. &ldquoThat rate isn&rsquot slowing down,&rdquo said Simpson. &ldquoIf anything, it might be speeding up.&rdquo
The availability of more capable sequencing technology such as single-cell transcriptomics is part of what&rsquos driving this trend in eukaryotes, especially for known unknown groups. It empowers researchers to glean usable DNA from single specimens. But Eme cautions that these methods still require the keen eye of skilled protistologists, like Eglit, &ldquoso that we can actually target what we want to look at.&rdquo
Another kind of sequencing, called metagenomics, could accelerate discovery even further. Researchers can now venture into the field, grab a sample of dirt from the trail or a biofilm from a deep-sea vent, and sequence everything in the sample. The catch is that it&rsquos usually just a snippet of one gene. For bacteria and archaea&mdashorganisms in the two other domains of life distinct from eukaryotes&mdashthat&rsquos usually enough to work with, and metagenomics has been behind recent huge discoveries such as the Asgard archaea, an enormous phylum of archaea totally unknown to science until about three years ago.
But for eukaryotes, which tend to have larger and more complicated genomes, metagenomics is a troublesomely broad way to sample. It reveals many types of organisms that live in an environment, &ldquobut unless you have a larger known reference sequence, it&rsquos very difficult to put these different things into an evolutionary framework,&rdquo Burki said. That&rsquos why, according to Simpson, most of the recent, really deep eukaryotic lineages have been discovered the &ldquoold fashioned&rdquo way, through identifying a weird protist in the lab and targeting it for sequencing.
&ldquoBut the two methods are complementary and inform one another,&rdquo Simpson said. For example, it&rsquos now clear that hemimastigotes popped up in previously published metagenomic databases. Yet &ldquowe just had no way of recognizing them until we had longer hemimastigote sequences to compare them to,&rdquo he said. Metagenomics can point to potential hot spots of unknown diversity, and deeper sequencing can make metagenomic data more meaningful.
The future is bright for researchers cataloging diversity, in both ordinary and extraordinary environments. While metagenomic tools allow us to explore extreme environments&mdashlike the sediment near hydrothermal vents where the Asgard archaea were found&mdashresearchers can also find new lineages in their backyards. &ldquoThis whole new supra-kingdom lineage was discovered by a graduate student out on a hike who happened to collect some dirt,&rdquo Burki said. &ldquoImagine if we could scan every environment on Earth.&rdquo
As scientists continue to fill out the tree, the algorithms used to add branches will only get more efficient, according to Eme. This will help researchers resolve deeper, more ancient splits in the history of life. &ldquoOur understanding of how life unfolded is still very much incomplete,&rdquo said Burki. Questions like why eukaryotes emerged or how photosynthesis evolved remain unanswered because &ldquowe don&rsquot have a tree that is stable enough to pinpoint where these key events happened,&rdquo he said.
Beyond answering such fundamental questions, the simple joy of discovery motivates researchers like Burki and Eglit. &ldquoThe microbial world is a wide-open frontier,&rdquo said Eglit. &ldquoIt&rsquos thrilling to explore what&rsquos out there.&rdquo
Reprinted with permission from Quanta Magazine, an editorially independent publication of the Simons Foundation whose mission is to enhance public understanding of science by covering research developments and trends in mathematics and the physical and life sciences.
Genomic prediction unifies animal and plant breeding programs to form platforms for biological discovery
The rate of annual yield increases for major staple crops must more than double relative to current levels in order to feed a predicted global population of 9 billion by 2050. Controlled hybridization and selective breeding have been used for centuries to adapt plant and animal species for human use. However, achieving higher, sustainable rates of improvement in yields in various species will require renewed genetic interventions and dramatic improvement of agricultural practices. Genomic prediction of breeding values has the potential to improve selection, reduce costs and provide a platform that unifies breeding approaches, biological discovery, and tools and methods. Here we compare and contrast some animal and plant breeding approaches to make a case for bringing the two together through the application of genomic selection. We propose a strategy for the use of genomic selection as a unifying approach to deliver innovative 'step changes' in the rate of genetic gain at scale.
Kailash Chandra, director of ZSI, said that modern taxonomic tools, like DNA analysis, helped in the discovery of frogs and reptiles
“Of the 61 species of vertebrates discovered this year, reptiles dominate (30 species),” Mr. Chandra said. 21 species of fishes, nine species of amphibians, and one mammalian sub-species were also found.
Kerala recorded the highest number of discoveries with 59 species. West Bengal, a state with both Himalayan and coastal ecosystems, recorded 38 and Tamil Nadu recorded 26.
With these new discoveries, the updated list of animal species in India has risen to 1,01,681 which is about 6.49% of all the species in the world, Mr. Chandra said.
S.S. Dash, head of the publication of BSI, said that the number of plant species in the country has been updated to 49,441 which is 11.5% of all flora in the world. “Over the past ten years, BSI has recorded discovery of 3,225 plant species,” he said.
Other than the discoveries, 139 species of animals were added to the fauna of India as new records. In terms of plants, 193 taxa of plants were added to flora of India as new records.
Last year, 539 new species of plants and animals were discovered, which included 300 species of animals and 239 species and sub-species of plants.
MATERIALS AND METHODS
MiRNA prediction from sRNA deep sequencing data
For miRNA predictions we downloaded, from GEO database ( 9), 171 small RNA deep sequencing libraries from 8 plant and 13 animal species ( Figure 1, Supplementary Table S1 ). Reads 19–26 bases long were kept and we mapped them to corresponding plant or animal genomes using Bowtie ( 10). In the mapping step, no mismatches were allowed and reads mapping to >20 distinct locations were discarded. Mapped reads that were 19–22-nt long and with count ≥ 5 were considered ‘potential mature miRNAs’. We retrieved their sequences from genomes along with flanking genomic sequences of 150 bases in animals and 250 bases in plants, and then we predicted secondary structures using hybrid-ss-min from UNAFold package ( 11). We kept only sequences with miRNA-like secondary structures: a stem loop-structure with ‘potential mature miRNA’ located in a single hairpin arm no more than six mismatches and three bulges (animals) or five mismatches and two bulges (plants) between mature miRNA and the opposite hairpin arm. If a stem-loop structure was surrounded by additional nucleotides, the flanking regions were cutoff. Subsequently, we checked similarity to non-coding RNAs from RFAM ( 12) and proteins from UniProt (UniProtKB/Swiss-Prot protein data set) ( 13) using BLAST ( 14). Sequences showing similarity to RFAM non-miRNAs with E < 1e-10 or UniProt proteins with E < 1e-20 were discarded. After that we searched for low-complexity regions using Dustmasker ( 14) sequences bearing >60% of low-complexity regions were removed. Finally, we made sure that there is a miRNA-like profile of reads mapped to the hairpin. To achieve this we kept only the hairpins where (i) ‘potential mature miRNA’ corresponded to the most abundant read in at least one library, (ii) abundance of ‘potential mature miRNA’ constituted minimal 20% of total read counts in at least one library and (iii) the total count of reads starting at 5′ position of ‘potential mature miRNA’ was the maximal one in at least one library.
The pipeline used for large-scale miRNA discovery from sRNA deep-sequencing data.
How chemical diversity in plants facilitates plant-animal interactions
A male Passerini's tanager, Ramphocelus passerinii, eats the fruit of Piper sancti-felicis. Photo by Bernadette Wynter Rigley. Credit: Bernadette Wynter Rigley.
We aren't the only beings who enjoy feasting on tasty fruits like apples, berries, peaches, and oranges. Species like bats, monkeys, bears, birds, and even fish consume fruits—and plants count on them to do so.
Wildlife disperse their seeds by eating the fruit and defecating the seed elsewhere, thus carrying the fruit farther away and spreading the next generation of that plant. But attracting wildlife might also mean attracting harmful organisms, like some species of fungi.
Plants walk a fine line between attraction and repulsion, and to do this, they evolved to become complex chemical factories. Chemical ecologists at the Whitehead Lab at Virginia Tech are working to uncover why plants have such diverse chemicals and to determine the functions of these chemicals in plant-microbe and plant-animal interactions.
"There is still so much we don't know about the chemical compounds plants use to mediate these complicated interactions. As we continue to lose global biodiversity, we are also losing chemical diversity and the chance for discovery," said Lauren Maynard, a Ph.D. candidate in the Department of Biological Sciences within the College of Science.
Piper sancti-felicis is a neotropical shrub related to Piper nigrum, which produces black peppercorn. Although P. sancti-felicis isn't as economically important as its peppery cousin, it fulfills an important ecological role as one of the first plants to colonize a recently disturbed area. It also serves as an important food source for wildlife, especially bats and birds.
At La Selva Biological Station in Costa Rica, Maynard and a team of international ecologists worked to better understand the evolutionary ecology of P. sancti-felicis. Their findings were recently published in Ecology and serve as a step forward in understanding why plants have such great chemical diversity.
By analyzing the samples, the team discovered 10 previously undocumented alkenylphenol compounds in P. sancti-felicis. Alkenylphenols are rare in the plant kingdom, as they have been reported only in four plant families.
The alkenylphenol compounds were not distributed evenly across the plant, though. Maynard found that fruit pulp had the highest concentrations and diversity of alkenylphenol compounds, while leaves and seeds had only a few compounds at detectable levels. Later, a pattern emerged: Levels of alkenylphenol were highest as flowers developed into unripe pulp, but then decreased as the pulp ripened.
When Maynard and her collaborators tested alkenylphenols with different species of fruit fungi, they found that the alkenylphenols had antifungal properties. But those same compounds also made the fruits less tasty to bats, which are the plant's main seed dispersers.
This is a delicate balance: high levels of alkenylphenols protected the fruit from harmful fungi as it developed, but when it ripened, alkenylphenol levels dwindled so that bats would be interested in eating it.
"Many fungal pathogens attack ripe fruits and can make fruits unattractive to dispersers, or worse, completely destroy the seeds. Our study suggests that these toxins represent a trade-off in fruits: They do deter some potential beneficial partners, but the benefits they provide in terms of protecting seeds outweigh those costs," said Susan Whitehead, an assistant professor in the Department of Biological Sciences.
This study is the first to document an ecological role of alkenylphenols. Chemical interactions in the plant kingdom are not easy to see, but they play a crucial role in balancing trade-offs in various interactions. In the case of P. sancti-felicis, alkenylphenols help the plant walk the fine line between appealing to seed dispersers and repelling harmful fungi.
"Finding the nonlinear pattern of alkenylphenol investment across fruit development was really exciting. It suggests that the main function of the compounds is defense," said Maynard, who is also an Interfaces of Global Change Fellow in the Global Change Center, housed in the Fralin Life Sciences Institute.
This discovery helps researchers understand the nuances of tropical forest ecology and how chemical diversity in plants helps maintain that delicate balance. Plant chemical defenses have mostly been studied in leaves of plants, so this new discovery furthers scientists' understanding of how and why these compounds are crucial in fruits. And because fruits are the vehicle for seed dispersal, these chemicals play a significant ecological role.
"This study advanced our understanding of how tropical forests work by bringing together scientists and expertise from multiple fields of study: plant ecology, animal behavior, chemistry, and microbiology," said Whitehead, who is also an affiliated faculty member of the Global Change Center and the Fralin Life Sciences Institute.
The Whitehead Lab has several ongoing projects focused on plant chemistry and seed dispersal at La Selva Biological Station. Since international travel is not possible at the moment, the team hopes to resume their research when it is safe to do so.
Plant and Animal Cloning (With Diagram)
In plants, agronomically important traits are governed by the genetic information stored in the nuclear and organellar (i.e., chloroplasts and mitochondria) genome and gene transfer can be done in all these genomes.
However, gene transfer in organelles specially in mitochondria is relatively difficult as compared to nuclear genetic transformation. The uptake of genes by cells in microbes and plants is termed as transformation.
Steps in plant genetic engineering:
The important steps involved in plant genetic engineering are as follows:
1. The first step is the identification and isolation of agronomically important gene.
2. The second step is cloning the isolated gene in a plant transformation vector.
3. The third important step is introduction of the gene into plant protoplasts, cells or tissues using gene transfer methods.
4. Now comes culture and regeneration of complete plants from genetically transformed cells on suitable selection medium.
5. The last important step is demonstration of the integration and expression of foreign gene in the transgenic plants by using molecular techniques.
Applications of Plant Genetic Engineering:
Till now, the plant genetic engineering has been successful in producing disease and pest resistant as well as herbicide tolerant transgenic plants. For example, in tomato the slow ripening process of the fruits is developed in soybean, corn and cotton herbicide tolerance is developed in potato, tomato, tobacco and rice viral resistance is developed.
Animal Cloning and Genetic Engineering:
Animal cloning is more difficult than plant cloning because animal cells lose their totipotency on reaching the gastrula stage of animal development. However, animal tissue cultures from tumours and embryonic tissue cells have been successful. Standard techniques are available for isolating animal cells and tissues from different systems.
Some more important examples of animal cloning are tissue culture, somatic cell fusion, cell cloning and creating transgenics.
Gene Transfer in Animals:
Gene transfer in animals is mostly through direct methods such as electroporation or microinjection or using particle gun. In creating ‘Dolly’ the cloned sheep, fertilised egg of its mother was removed by micro-needle and nucleus from an udder cell of a donor sheep was microinjected in the egg after removing egg nucleus. The egg developed into ‘Dolly’ with genes identical to its mother.
Applications of Animal Cloning and Genetic Engineering:
Examples of animal products (medicines) produced through genetic engineering are:
(i) Chick embryo fluid which produces vaccines for influenza, measles and mumps,
(ii) Duck embryo fluid which produces vaccines for rabies and rubella.
How Sheep ‘Dolly’ Cloned?
Ian Wilmut and his associates at the Roslin Research Institute, Scotland, took cells from ewe (mother sheep’s udder). An udder cell is different from a skin cell or a muscle cell or a nerve cell.
They managed to store these udder cells in nutrient deprived culture. This checked the starved cells from dividing, and switched off their active genes.
Now, one udder cell complete with its nucleus was selected, as this nucleus carries the mother’s genetic information.
Meanwhile, unfertilized egg cell was taken from a different ewe (host mother sheep). Its nucleus was sucked out leaving an empty cell containing all the necessary components to produce an embryo. This cell was now ready to receive udder cell nucleus.
They now fused udder cell nucleus with the empty egg cell by electrical stimulation. Then this egg cell had the mother’s nucleus.
When a normal or altered egg is implanted in a different female is termed ‘surrogate mother’. This means, substitute mother.
Then the altered egg was cultured for six days. Out of many resulting embryos, one was implanted in the uterus of the surrogate mother, where it grew into a lamb.
Thus, Dolly was born genetically identical to mother sheep as her first cell nucleus came from mother’s cell.
How Calves are Cloned in Japan?
Scientists from Japan have cloned cattle in a different way.
They have got success in growing as many as eight identical calves from one fertilized cell of their mother.
The process is as follows:
When the mother cow has mated with the bull, she has a fertilized egg in her womb. Now this zygote divides in two and then in four and then in eight. This embryo is carefully removed from the womb, and the embryonic cells are separated using as enzyme.
Each isolated cell is kept in a nutrient medium and later implanted in the womb of a different ‘host mother’ cow.
The host mother’s womb must accept the cell and make it grow. Each cell may grow into a normal baby calf, if all goes well.
The birth of the first human clone (December 26, 2002), a baby girl called Eve by scientists, was announced by Brigitte Boisselier, head of a company named Clonaid. According to Boisselier, the child is an exact genetic duplicate of her mother.
To clone, scientists slip the nucleus of an adult cell, like a skin cell, into an unfertilized egg from which its own genetic material has been removed.
Then, if stimulated to act like a fertilized egg, the newly altered genetic material can then direct the egg to divide and grow into an embryo, then a foetus, then a newborn, if all goes well. Yet, as scientists have discovered, only rarely does all go well.
In animal work so far only about 1 to 5 per cent of cloning attempts succeed, said Randall Prather, a cloning expert. That is, for every 100 eggs, one to five clones are born.