which disrupts a cell wall remodeling process critical for the greening bacteriumâ##s survival inside a citrus tree. â#oeas a consequence of the chemical treatment several genes were expressed not
The research group performed a comparative analysis of DNA sequence variation of land planarian by means of a nuclear and a mitochondrial gene.
It provides new avenues to discover resistance genes and helps explain the mechanisms of repeated emergence of this disease which to this day is still the most costly potato pathogen in the world.
This should allow us to make significant headway in finding additional genes that provide resistance to P. infestans.
Gene sequencing technology used by this research group helped pin down the Toluca Valley as the ancestral hot spot. The P. infestans pathogen co-evolved there hundreds of years ago with plants that were distant cousins of modern potatoes
Since different potato varieties plants and pathogens have been co-evolving there for hundreds of years it offers some of the best hope to discover genes that provide some type of resistance.
In their study reported in BMC Plant Biology the researchers used gene sequencing techniques to identify 11 naturally occurring bacteria isolated from rice plants grown in the field in California.
#What can plants reveal about gene flow? That its an important evolutionary forcea plant breeder discovers his experimental crops have been contaminated with genes from a neighboring field.
New nasty weeds sometimes evolve directly from natural crosses between domesticated species and their wild relatives.
They illustrate the important role of gene flow among populations and its potential consequences. Although gene flow was recognized by a few scientists as a significant evolutionary force as early as the 1940s its relative role in maintaining a species'genetic integrity
and/or its diversity has been debated over the decades vacillating from trivial to critical. So how much gene flow is there between plant populations?
How important is gene flow for maintaining a species'identity and diversity and what are the implications of these processes for evolution conservation of endangered species invasiveness
or unintentional gene flow from domesticated crops to wild relatives? Norman Ellstrand a plant geneticist at the University of California Riverside is interested in many aspects regarding gene flow especially in applied plant biology
and has spent more than 25 years considering the possibility and potential impacts of unintended gene flow from genetically engineered crops.
As part of the American Journal of Botany's Centennial Review series Ellstrand reviews the history of gene flow focusing on plants
and provides evidence for its importance as an evolutionary force. Selection mutation gene flow and genetic drift are the four mechanisms that lead to biological evolution or a change in allele frequencies in a population over time.
Just how important are each of these forces relative to each other? Interestingly Ellstrand points out that evolutionary biologists'view on the importance of gene flow has waxed
and waned over the last century. Although it was seen first in the 1940s to be the evolutionary glue that held species together
and thus a significant evolutionary force a few decades later when quantitative data on gene flow in plant populations began being collected this view changed as evidence seemed to indicate that gene flow was not all that significant.
Not only was intraspecific gene flow among populations seen to be minimal at that time but somewhat incongruously interspecific hybridization or the movement of genes among species was seen to be a much larger force in evolution than intraspecific allele movement.
At the time the main concern for plant breeders was pollen movement between different strains of crops
--if a variety of sweet corn was contaminated by pollen from a popcorn variety then the resulting hybrid offspring would produce seeds that were unusable for market purposes
When I first started doing plant paternity studies in the 1980s Ellstrand comments our lab assumed that gene flow was limited.
And the paradigm of limited gene flow in plants began to crumble. Indeed one of the amazing things that parentage studies revealed is just how far genes could flow from hundreds to thousands of meters in some cases.
In one extraordinary case a study found that the nearest possible paternal sire of an individual fig tree was 85 km away!
but changes in allele patterns over time and thus the effects of evolution on populations can be seen in the genetic information.
despite the initial skepticism about the importance of gene flow modern empirical and theoretical research using up-to-date molecular
and DNA techniques have shown us not only how surprisingly far the flow of genes between distant plant populations can be
but also that the flow of alleles among populations is just as important if not more so in some cases as natural selection.
Indeed even just a low level of gene flow between populations can counter opposing forces of mutation genetic drift and selection.
Just like selection gene flow is one of the evolutionary forces--and a potentially important one notes Ellstrand.
And plants are suited very well for studies on gene flow because individuals are stationary yet pollen
However an important caveat that Ellstrand reports in his review is that the relative importance of gene flow can vary tremendously among species
and among populations and can be as low as no gene flow at all to very high rates of gene flow.
This review paper tells the story of gene flow's rise to respect among plant evolutionary biologists he concludes a fact that hasn't yet penetrated biology in general that is still mired in selection/adaptation-only thinking.
#Understanding disease resistance genes in crops to secure future food productiona new understanding as to how plants defend themselves against some pathogens that cause crop diseases is proposed by researchers from the University of Hertfordshire to help scientists
The second line of defense is referred to as effector-triggered immunity (ETI) this is based on the detection of disease pathogens by the plant's genes--there is a relationship between the gene in the host plant and the gene in the pathogen.
Through our research we discovered that defense against extracellular pathogens (ETD) involves different plant genes from those involved in the defense against intracellular pathogens.
We identified some specific resistance genes that code for receptor-like proteis (RLPS) and described how they operated against the pathogens.
This new understanding of plant defense through ETD suggests different operations of specific resistance genes
which both copies of the gene encoding Galt (galactosyltransferase) the enzyme responsible for placing the Gal molecule on the cell surface were knocked out.
The emergence of resistant pink bollworm in India provided the researchers an opportunity to test the hypothesis that insects in the field would evolve resistance to Bt toxin by the same genetic mechanism found previously in the lab. In the lab strains the scientists had identified mutations in a gene
if field-resistant pink bollworm from India harbored these same changes in the cadherin gene Fabrick said.
He said that by collaborating with Indian scientists we discovered that the same cadherin gene is associated with the resistance in India
and in 2004 Kang's group reported that mice transgenic for a c. elegans gene called fat-1 converted omega-6s into omega-3s in their tissues.
The current study describes how crossbreeding the fat-1 mouse with another strain transgenic for the c. elegans gene fat-2
which converts monosaturated fats into omega-6s can produce mice expressing both c. elegans genes.
The crossbreeding protocol produces four different strains within the same litter--Omega mice that express both fat-1 and fat-2 strains that express only one of the c. elegans genes
and weeds affect each other's gene response Clay and a team of two research associates and a soils expert planted plots of velvetleaf alone corn with velvetleaf and corn kept weed-free.
In addition specific genes that influenced photosynthesis and other important plant responses differed in expression. Another study compared the corn's growth and yield in response to weeds lack of nitrogen or shade.
In all cases Clay and Horvath found that genes were expressed differentially compared with nonstressed plants.
When grown with weeds genes that control the major facets of the corn plant's metabolism were decreased
The genes never recovered says Clay even after the weeds were removed. The impact is long term she adds
The genes of the water-stressed corn on the top of the hill were regulated down in terms of phosphorus uptake Clay explains.
Further these expansions result from large-scale gene duplications that took place independently in different sap-eating insects.
Gene duplication is a process that occurs when part of an organism's genetic material is replicated.
Groups of similar genes that share an evolutionary ancestry are called gene families. Given the extensive gene duplication of the amino acid transporter gene families that took place multiple times independently in sap-feeding insects it makes sense that gene duplication might be important for recruiting amino acid transporters to mediate
amino acid exchange between these insects and their symbionts said Rebecca P. Duncan doctoral student in the Department of biology at UM and first author of the study.
However given that the genes expanded independently in each insect sap-feeding insects likely evolved their relationships with their symbionts separately as opposed to in their common ancestor.
To study the historical effects of interactions between genes and between genes and the environment they looked at genes controlling several crop plant traits.
Domestication has yielded modern crops whose seeds resist shattering such as corn whose kernels stay on the cob instead of falling off.
whether genetic factors hindered transmission of genes controlling such traits. Instead they found that domestication traits are passed often faithfully from parent to progeny
#Involvement of gene in lentivirus infections of sheep, goats has been establishedin her Phd thesis Helena Crespo-Otano has studied the mechanism of the action of the small ruminant lentivirus (SRLV) a type of virus
and characterised the ovine MR gene and have determined its involvement in the entry of the virus into the cells that express it.
Plant immunity that is controlled by a single resistance gene on which most conventional breeding programs are based is comparably easy to overcome by a pathogen.
In addition Zurek's team showed that bacteria in the house fly digestive tract can exchange antibiotic resistance by horizontal gene transfer.
We were excited to find that higher calcium intake appears to mitigate the impact of some of the risk genes for type 2 diabetes
Among children who tested positive for gene variants known to be associated with type 2 diabetes those who consumed higher amounts of calcium had a significantly lower body mass index and percent body fat than those with lower
or related dietary factors may cause epigenetic changes that affect how the diabetes-linked genes are expressed.
Understanding the interactions of genes and environmental factors in children is especially helpful for a disease as complex as diabetes said Devaney.
As the result of recent improvements in technology for genetic modification of pigs genes that are immunogenic for humans have been eliminated('knocked out) and several human genes have been added to the pig genome.
Through the combination of a pig heart with certain gene modifications with drugs suppressing both T
The study is published in the April 1 issue of the journal Genes and Development. The first author of the report is Tongde Wu a graduate of the UA Department of Pharmacology
The study Hrd1 suppresses Nrf2-mediated cellular protection during liver cirrhosis is published in the April 1 issue of the journal Genes and Development.
Genes from dwarf birch were found in birch tree populations across Britain which reflects a much wider distribution occupied by the wee tree
As dwarf birch moved north some of its genes were picked up by downy birch trees which spread through Britain at the cost of dwarf birch.
As global warming continues stray genes and fossils could be all that is left of dwarf birch in Britain.
which is used commonly as a farm soil fertilizer contains a surprising number of newly identified antibiotic resistance genes from the cows'gut bacteria.
The findings reported in mbioâ the online open-access journal of the American Society for Microbiology hints that cow manure is a potential source of new types of antibiotic resistance genes that transfer to bacteria in the soils
Thousands of antibiotic resistance (AR) genes have already been identified but the vast majority of them don't pose a problem
when these genes appear in the types of pathogenic bacteria that cause food-borne illnesses
or hospital infections Since there is a connection between AR genes found in environmental bacteria and bacteria in hospitals we wanted to know what kind of bacteria are released into the environment via this route of manure fertilization says Fabienne Wichmann lead study author and former postdoctoral researcher at Yale university in New haven Connecticut.
and they or their genes might move to the human ecosystem. Is this a route for movement of these genes from the barn to the table?
asks Jo Handelsman senior study author and microbiologist at Yale. The first step toward an answer was surveying
which AR genes are present in cow manure. Handelsman's team used a powerful screening-plus-sequencing approach to identify 80 unique and functional AR genes.
The genes made a laboratory strain of Escherichia coli bacteria resistant to one of four types of antibiotics--beta-lactams (like penicillin) aminoglycosides (like kanamycin) tetracycline or chloramphenicol.
Roughly 75%of the 80 AR genes had sequences that were only distantly related to AR genes already discovered.
The team also found an entire new family of AR genes that confer resistance to chloramphenicol antibiotics which are used commonly to treat respiratory infections in livestock.
The diversity of genes we found is remarkable in itself considering the small set of five manure samples says Handelsman who is also a Howard Hughes Medical Institute Professor.
But also these are evolutionarily distant from the genes we already have in the genetic databases
which largely represent AR genes we see in the clinic. That might signal good news that AR genes from cow gut bacteria are not currently causing problems for human patients.
But Wichmann points out another possibility is that cow manure harbors an unprecedented reservoir of AR genes that could be next to move into humans.
This is just the first in a sequence of studies--starting in the barn moving to the soil
and food on the table and then ending up in the clinic--to find out
whether these genes have the potential to move in that direction says Handelsman. AR genes can enter the human ecosystem by two routes--either the bacteria that contain them colonize humans
or the genes are transferred through a process called horizontal gene transfer to other bacteria that colonize humans.
Research has shown already that bacteria are transferred from farm animals to their human caretakers. Gene transfer enables genes to jump between microorganisms that are related not
and it occurs in most environments that host bacteria. Some manure bacteria might be pathogenic to humans
Alternatively benign bacteria in manure might transfer resistance genes to pathogens at any point along the path--in manure soil food or humans.
Olsen on the other hand seeks to identify genes in modern crop species that are associated with domestication traits in the plant such as an erect rather than a sprawling architecture.
The techniques used to isolate these genes are difficult and time consuming and may not always penetrate as deeply into the past as scientists had assumed once
The researchers focused on two genes known to differ between domestic chickens and their wild counterparts:
a gene associated with yellow skin color called BCDO2 and a gene involved in thyroid hormone production called TSHR.
Though the exact function of TSHR is unknown it may be linked to the domestic chicken's ability to lay eggs year-round--a trait that Red Junglefowl
Similarly less than half of the ancient chickens had the version of the TSHR gene found worldwide in modern chickens.
We suspect the seemingly greater tolerance of African bees to these pests over the western bees is a combination of genes and environment.
and indicate long-term gene flow or interbreeding between managed and wild animal populations Marshall said.
These management practices placed only light selection pressure on the herd's gene pool. Paradoxically environmental selection may in many instances have been stronger than artificial selection.
and gene flow highest in the case of pack animals such as donkeys or camelids. But even in the case of pigs or cattle interbreeding between domestic and wild animals has created long and complex evolutionary and domestication histories that challenge assumptions regarding genetic isolation and long-held definitions of domestication.
and the likelihood of long-term gene flow from the wild. It's probably fortunate the Darwin had clear examples of animal breeding to consider as he thought about evolution.
Olsen said favored gene variants (alleles) that are relatively insensitive to background effects and highly responsive to selection.
But finding these alleles in the first place must have said difficult Olsen. Only a subset of the genes in the wild population would have produced reliably a favored trait regardless of the crop variety into
which they were bred and regardless of where that crop was grown. So the early stages of domestication might have been beset by setbacks
Over the past 20 years researchers have begun to identify the genes that control some of the most important domestication traits no easy task in the days before rapid sequencing
because they had to start with plant traits and work back to unknown genes. This work showed that many domestication traits were under the control of single genes.
For example the gene teosinte branched1 (tb1) converts highly branched teosinte plants into single stalks of corn.
But the seeming importance of single genes could have been an artifact of the method used to identify domestication genes which required the researcher to pick candidate genes
and perhaps prematurely narrow the search overlooking indirect genetic effects. Little is known about the underlying genetics of domestication Olsen said.
The new work examines the possibility that two indirect effects--the influence of the genetic background on the expression of a gene (called epistasis)
and the effects of the environment on the expression of genes--might have slowed the selection of plants with the desired traits.
or linked to genes that underlie this trait a major one called QTL 1 and a minor one called QTL2.
In this as in other epistatic interactions the effect of an allele at one location depends on the state of the allele at the other location.
Shattering in plants with a wild green-millet allele at the QTLI location depends on the allele at the QTL2 location.
In contrast shattering in plants with the foxtail-millet allele at QTL1 is unaffected by the allele at the QTL2 location.
In the limited number of examples at their disposal the scientists found it to be generally true that that domesticated alleles were less sensitive to genetic background than wild alleles.
The domestication genes in other words tended to be ones that would produce the same result even if they were introduced into a different crop variety.
When a teosinte plant with a wild tb1 gene is backcrossed repeatedly with maize it produces highly branched plants in uncrowded growing conditions
plants with the domesticated tb1 gene allele are unbranched whether or not they are crowded. Unlike companion-animal breeders early farmers seem to have selected domestication-gene alleles that are insensitive to genetic background and to the environment.
This process would have been slow unrewarding and difficult to understand because the effects of gene variants on the plant weren't stable.
But once sensitive alleles had been replaced with robust ones breeders would have been able to exert strong selection pressure on plant traits shaping them much more easily than before
and the pace of domestication would have picked up. No wonder the archeological record indicates there were false starts failed efforts and long delays.
#Synthetic gene circuits pump up cell signals in study of neurodegenerative diseasessynthetic genetic circuitry created by researchers at Rice university is helping them see for the first time how to regulate cell mechanisms that degrade the misfolded proteins implicated in Parkinson's Huntington
or genes that can increase proteasomal activity she said. This will help us rationally design compounds
The scientists introduced into mice the gene that codes for the normal bank vole prion protein thereby generating mice that express bank vole Prp but not mouse Prp.
Researchers had tried previously to tackle this problem by reducing the quantity of lignin in trees by suppressing genes
but there are ways to ensure that the genes do not spread to the forest. These techniques include growing crops away from native stands
introducing genes to make both the male and female trees or plants sterile; and harvesting trees before they reach reproductive maturity.
When crossing parent plants for example breeders often like to track the genes underlying their trait of interest such as resistance to a pathogen.
That's because pinpointing offspring that carry the right genes is often faster and easier than examining plants for the trait itself.
But sometimes so many genes contribute to a single trait that figuring out which genes are involved in the first place becomes onerous.
This is where Hoekenga thinks his style of research and analysis might one day help. We're trying to describe at the biochemical level what might be responsible for a trait.
The sequences provide researchers access to 96 percent of all peanut genes in their genomic context providing the molecular map needed to more quickly breed drought-and disease-resistant lower-input and higher-yielding
Being able to see the two separate structural elements also will aid future gene marker development-the determination of links between a gene's presence and a physical characteristic of the plant.
#Genes identified that could lead to tough, disease-resistant varieties of riceas Earth's human population marches toward 9 billion the need for hardy new varieties of grain crops has never been greater.
Now researchers at Michigan Technological University have identified a set of genes that could be key to the development of the next generation of super rice.
A meta-data analysis by biologist Ramakrishna Wusirika and Phd student Rafi Shaik has uncovered more than 1000 genes in rice that appear to play key roles in managing its response to two different kinds
Traditionally scientists have believed that different sets of genes regulated plants'responses to biotic and abiotic stress.
However Wusirika and Shaik discovered that 1377 of the approximately 3800 genes involved in rice's stress response played a role in both types stress.
These are the genes we think are involved in the cross talk between biotic and abiotic stesses said Wusirika.
About 70 percent of those master genes are co-expressive--they turn on under both kinds of stress.
The scientists looked at the genes'response to five abiotic stresses--drought heavy metal contamination salt cold and nutrient deprivation--and five biotic stresses--bacteria fungus insect predation weed
A total of 196 genes showed a wide range of expressions to these stresses. The top genes are likely candidates for developing a rice variety with broad stress-range tolerance Wusirika said.
Next they would like to test their findings. We want to do experimental analysis to see if five or 10 of the genes work as predicted he said.
Their study is described in the paper Machine learning Approaches Distinguish Multiple Stress Conditions using Stress-Resposive Genes
and Identify Candidate Genes for Broad Resistance in Rice published in the January edition of Plant Physiology.
Story Source: The above story is provided based on materials by Michigan Technological University. The original article was written by Marcia Goodrich.
what we saw was an inhibition of a marker gene in the lungs after a few weeks indicating an inhibition of metastasis
#Instrument built to study effects of genes, environment on plant traitslet's say plant scientists want to develop new lines of corn that will better tolerate long stretches of hot dry weather.
It contained additional four virulence genes making it extremely invasive and ultimately caused 14 cases resulting in 5 deaths.
and validate genes from the P450 detoxification enzyme superfamily which are expressed highly in the adult females from the area.
The new work reveals that two members of the P450 gene superfamily in particular are expressed highly in resistant Tiassalã mosquitoes:
When these genes were transplanted into Drosophila resistance to pyrethroids and carbamates was generated in otherwise susceptible fly strains..
These genes are familiar candidates to LSTM researchers who have documented previously their links with pyrethroid and DDT resistance.
This new research shows how specific P450 genes can engender resistance across insecticides with entirely different modes of action:
whereas carbamates and organophosphates target the neurotransmitter Acetylcholinesterase encoded by the gene ACE-1. This is where Tiassalã mosquitoes yielded another surprise contributing to their exceptionally high carbamate resistance.
A well-known single nucleotide resistance mutation at the ACE-1 gene is near ubiquitous in the population
but because almost every female is a heterozygote (possesses a resistant and susceptible allele) it did not seem this could cause any variation in resistance.
However from application of a newly-developed qpcr diagnostic it was found that the ACE-1 gene was duplicated in some individuals with those resistant to carbamate much more likely to have duplicated additional copies of the resistant ACE-1 allele.
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