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Conseils/Advice on designing scientific posters

24 Février 2009,

Publié par JMB

Advice on designing scientific posters: link 
(by Colin Purrington, Department of Biology, Swarthmore College, Pennsylvania)

A one-sentence overview of the poster concept

A scientific poster is a large document that can communicate your research at a scientific meeting, and is composed of a short title, an introduction to your burning question, an overview of your trendy experimental approach, your amazing results, some insightful discussion of aforementioned results, a listing of previously published articles that are important to your research, and some brief acknowledgement of the tremendous assistance and financial support conned from others—if all text is kept to a minimum, a person could fully read your poster in under 10 minutes.

 


 

Creating effective poster presentations: link
(by G. Hess, K. Tosney, and L. Liegel)

 

Des conférences vidéo, audio...

21 Février 2009,

Publié par JMB

 La direction des Savoirs en multimédia met les ressources du multimédia au service d'une mission de l’École normale supérieure : contribuer à diffuser les savoirs d’aujourd’hui auprès du public spécialisé – chercheurs, enseignants, étudiants et élèves – et du grand public en quête de connaissances nouvelles.

Ce portail donne accès au catalogue audiovisuel de l’École normale supérieure. Vous y trouverez les enregistrements de cours, séminaires, écoles d’été, conférences, semaines culturelles, journées d’études et colloques des départements et laboratoires (Sciences et Lettres) et des
événements de prestige organisés à l’École normale supérieure.

Pour y accéder, cliquez ici

Si vous préférez le jazz, le blues, le wester swing, je vous propose de découvrir Susie Arioli (écouter aussi ses albums CD : le son est divin sur une bonne chaîne Hifi)



Génétique et sélection animale

21 Février 2009,

Publié par JMB

Des cours mis en ligne par  l'UFR Génétique, élevage et reproduction (Département des Sciences de la Vie et Santé) d'AgroParisTech

- Les outils d'analyse du polymorphisme génétique
- Ressources génétiques
- Eléments de génétique des populations appliqués à l'élevage
- Génétique quantitative
- Gén'éthique


Pour y accéder : lien

Réseau d'Enseignement en Génétique : GENET

21 Février 2009,

Publié par JMB

Le réseau GÉNET a pour but de fournir un support pour l'enseignement de la Génétique en utilisant plus spécifiquement les ressources du multimédia. Réalisé sous la responsabilité des établissements partenaires, il est soutenu par des actions de l'Agence Universitaire pour la Francophonie, programme "Technologies de l'information et de la communication et appropriation des savoirs". Le réseau fait également appel à des collaborations individuelles, en établissant des liens sur des sites d’intérêt général.

Les modules proposés correspondent à différents niveaux du système d’enseignement universitaire européen (3 années de Licence, deux années de Master). A titre indicatif, les modules de base pour la Licence sont indicés: L1-L2, et les modules avancés: L3 ou M.

Le site web de la biodiversité canadienne

21 Février 2009,

Publié par JMB

Le Musée Redpath présente le site web de la biodiversité canadienne/The Canadian Biodiversity Web Site


Quelques extraits de ce site vraiment bien fait (théorie de la biodiversité, législation,...) :

"Qu'est-ce que la biodiversité?

Nous entendons de plus en plus parler de biodiversité, ou diversité biologique, mais très peu de gens savent exactement ce que ces termes recouvrent. Les observateurs et les experts en proposent d'ailleurs un nombre incalculable de définitions (voir la longue liste qui figure dans le premier chapitre de Gaston, 1996). Nous en retiendrons deux ici. La première provient de la Convention sur la diversité biologique adoptée au Sommet de Rio de 1992 : " Variabilité des organismes vivants de toute origine y compris, entre autres, les écosystèmes terrestres, marins et autres écosystèmes aquatiques et les complexes écologiques dont ils font partie; cela comprend la diversité au sein des espèces et entre espèces ainsi que celle des écosystèmes. " La seconde est inscrite dans la Stratégie canadienne de la biodiversité : " […] la multitude des espèces et des écosystèmes de la Terre ainsi que les processus écologiques dont ils font partie. " Très souvent, le terme " biodiversité " s'entend dans un sens très général et désigne simplement la nature. Aucune définition n'est parfaite. Comme la vie elle-même, chacune d'elles comporte des zones nébuleuses et souffre plusieurs exceptions.

 

Un site web sur la biodiversité : pour quoi faire?

Sur le plan biologique, notre planète présente une diversité ahurissante. Elle héberge des dizaines de millions d'espèces, dont seul un nombre restreint ont été identifiés jusqu'ici. Au Canada aussi, la pluralité des formes de vie et des écosystèmes a de quoi surprendre. De la forêt pluviale au désert, hérissés de montagnes ou étalés en plaines, ses paysages sont multiples et abritent des espèces bien adaptées aux conditions environnantes qui leur sont propres. Malgré ce foisonnement de la vie et des reliefs, rares sont les Canadiens qui mesurent vraiment la diversité biologique de leur pays.

Nous savons donc peu de choses de notre globe et de sa pluralité. Or, celle-ci est menacée. Les impacts que nous, les êtres humains, et nos activités exerçons sur la planète suscitent une inquiétude grandissante. À l'origine de la pollution, de l'érosion, de la désertification, de l'accélération des extinctions et de plusieurs autres phénomènes préoccupants, il y a l'homme. Autrefois, les effets négatifs de nos activités s'avéraient tout au plus contrariants ou ne posaient vraiment problème que dans une région bien circonscrite, à un échelon purement local. Aujourd'hui, ils modifient les paramètres mêmes de la vie sur Terre.

Déjà, des changements majeurs sont enclenchés et personne ne peut prédire l'ampleur de leurs impacts. Ils renvoient à des problématiques cruciales, à des questionnements essentiels, et ils exercent et continueront d'exercer des effets profonds sur la biodiversité. La plupart des notions de base de la biodiversité sont connues depuis longtemps, notamment dans les sphères de l'écologie et de l'évolution. Malheureusement, l'étude de la biodiversité proprement dite et son objectif principal, qui consiste à établir le lien entre toutes ces données, sont encore relativement jeunes. En d'autres termes, tandis que les chercheurs s'efforcent de comprendre et de mesurer la diversité de la vie qui nous entoure, celle-ci se réduit comme peau de chagrin.

Le but de ce site est de faire le point sur les enjeux de la biodiversité, sur ce que nous savons d'elle aujourd'hui, sur ce que nous faisons et devrons faire à l'avenir.

What is biodiversity?

Biological diversity, or biodiversity, is a term that is becoming more and more heard, yet few people really know what it is. There are many definitions for it (see the first chapter of Gaston (1996) for a long list), but there are two that will be given here. The first is from the Convention on Biological Diversity, also known as the Rio Summit: "'Biological diversity' means the variability among living organisms from all sources including, inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part; this includes diversity within species, between species and of ecosystems." The Canadian Biodiversity Strategy defines it as "…the variety of species and ecosystems on Earth and the ecological processes of which they are a part". It is often simply used as a catch-all term for nature. No definition is perfect; as with life itself, it's a bit nebulous and there are always exceptions.

 

Why a web site on biodiversity?

Biologically, the world is an astoundingly diverse place. It contains tens of millions of species, only a fraction of which have been identified. Canada's diversity of lifeforms and ecosystems is also large. Its landforms range from rainforest to desert, with mountains and plains, and each has species adapted to the conditions present there. Despite this diversity of life and land, most people have little idea of how diverse the country really is.

At the same time that little is known about the planet's diversity, it is also threatened. The effect that we humans and our activities have had on our planet have become a major concern. Pollution, erosion, desertification, increased rates of extinction and more can all be traced back to us. While these results of our activity were once simply unpleasant or only a real problem locally, they are now starting to completely change the face of life on the planet.

Changes are already happening, and no one knows how serious the results will be. These are enormous issues and concerns, and what they affect is biodiversity. Unfortunately, although many of the fundamental concepts included in the term biodiversity have been known for some time in ecology and evolution, the field of biodiversity and its goal of tying together all this information are fairly new. What this means is that researchers are trying to understand the diversity of life as it is being swept away all around us.

What we need is to understand what is at stake, what has been learned, and what we are doing and still need to do. That is the purpose of this site. "

Analyse de puissance : logiciel G*Power

21 Février 2009,

Publié par JMB

Un logiciel gratuit pour réaliser des analyses de puissances : G*Power
G*Power 3 is a statistical power analysis program for MacOS X 10.4 and Windows XP/Vista. It is a major extension of, and improvement over, the previous version, covering many different statistical tests of the F, t, chi-square, and z test families as well as some exact tests. G*Power 3 provides improved effect size calculators and graphics options, it supports both a distribution-based and a design-based input mode, and it offers five different types of power analyses. Like its predecessors, G*Power 3 is free.
Download and register G*Power 3

Pour en savoir un peu plus sur les analyses de puissances, vous pouvez lire cet article : L. Thomas et C.J. Krebs (1997). "A review of statistical power analysis software".


How to Use G*Power

by Axel Buchner, Edgar Erdfelder, and Franz Faul.

First published on the WWW: August 28, 1997; last update: March 28, 2001.


This manual was designed for G*Power 2. The next version,
G*Power 3, is now available. The information provided here may still be helpful, however, because the help pages for G*Power 3 will remain incomplete for some time to come.

This is what you find here:

  1. a short tutorial
    for first time users contains an example which shows, step by step, how to do power analyses with G*Power;

  2. a user interface description
    explains how G*Power works (and contains lots of graphics, so be prepared to see slow downloads);

  3. a reference section for experienced users describes how different
    1. types of power analyses are done for a number of
    2. statistical tests and gives some details about the
    3. underlying theoretical concepts;
  4. a programmatic article
    provides a brief overview of the use of power analyses in behavioral research, explains why G*Power was developed, and informs about the algorithms used in the program;

  5. a list of questions and answers
    about how to perform power analyses with G*Power may help you with a specific problem;

  6. a list of the people who were very helpful in improving G*Power and this guide to G*Power.

Jorge Camacho-Sandoval, Costa Rica (jcamacho@ice.co.cr) has compiled a PDF version of the tutorial and the reference section which he kindly provided for download.


Where do I get the latest version of the program?

Check out our G*Power 2 web page to see if you do not have it already. Please note that the next version, G*Power 3, is now available. You may still use G*Power 2, and in some cases you have to: If you still use MS-DOS or MacOS 7 to 9 as operating systems, you are limited to G*Power 2. For all others, G*Power 3 is highly recommended.

 

Note

The information presented on these pages about statistical power analyses is designed to help users with different levels of experience in performing power analyses with G*Power. It must not be used for other purposes without explicit permission by the authors.

Although we have spent considerable time developing this web-based guide to G*Power, we can, of course, not guarantee that the text is free of errors. If you detect an error, or an omission which you think is crucial, then we would really appreciate if you could contact us.

If you want to cite this manual, this would be an appropriate format

Buchner, A., Erdfelder, E., & Faul, F. (1997). How to Use G*Power [WWW document]. URL http://www.psycho.uni-duesseldorf.de/aap/projects/gpower/how_to_use_gpower.html

 

About the terminology

Because HTML widely lacks features to display Greek and mathematical symbols, we used iso8859-1 (Latin-1) char set with fixed character width to display mathematical expressions.

Statistics for ecologists

21 Février 2009,

Publié par JMB

Herrera Lab | Carlos Herrera page

Statistics for ecologists

 

A collection of links to sites with mathematical and statistical material (software, documents) that may be useful to ecologists and evolutionary ecologists

 

Ecologically-oriented software | Structural Equation Modelling

SAS-related stuff  | General Statistical Libraries

 

Ecologically-oriented software

Clearinghouse for Ecology Software
University of Tennessee Mathematical Life Sciences Archives WWW Server for Statistics and Analysis Software
Links for Palaeobotanists
Kovach Computing Services MVSP, ORIANA (Circular Statistics), SIMSTAT
Pierre Legendre's Home Page
R package Home Page
Morphometrics at SUNY Stony Brook The best site on Earth for morphometric software.
UTK Mathematical Life Sciences Archives
Common Principal Components Patrick Phillips' Software Page
On-line software for Clustering and Multivariate Analysis
Colorado State University Dept of Fishery and Wildlife Biology
ADE-4 Statistical Package
Digital Taxonomy Morphometrics and Biodiversity Data Management
PC-ORD Multivariate analysis for ecological data
DISTANCE Home Page Distance sampling surveys of wildlife populations
EstimateS Statistical Estimation of Species Richness, by Robert K. Colwell
Patuxent Software Archive Patuxent Wildlife Research Center Software Archive
MARK Home Page Analysis of data from marked individuals
Mauro Cavalcanti's collection of Software and Links
Geostatistical Software for PC

Structural equation modelling (SEM) and path analysis

Filip Lievens' site
Ed Rigdon's SEM FAQ

SAS-related stuff (docs, faqs, macros, programs, news)
SAS Institute:
          
SAS Institute Home Page
          
SAS Documentation/Publications
          
SAS Institute FTP server
Macros and programs:
          
Collection of SAS macros - Univ. Heidelberg
          
SAS Macros for Exploratory Data Analysis SAS macros by Dominique Ladiray
          
SAS Graphic Programs and Macros by Michael Friendly
          
SAS Sample Library File Contribution Server
          
O. Schabenberger' page
          
Arnold Schick's SAS Pages
          
SAS macros Mayo Clinic College of Medicine
          
UCLA Resources to help you learn and use SAS
General Info, FAQs and Manuals:
          
SAS Coding Tips and Techniques
          
ISD Web Information on SAS
          
SAS Information Guides

General mathematical and statistical libraries, documents and sites of interest

The R Project for Statistical Computing

Statistics and Statistical Graphics Resources Michael Friendly's
Annotated Bibliography of Articles for the Statistics User
GAMS : Guide to Available Mathematical Software
The World-Wide Web Virtual Library: Statistics 
Resampling Stats
St@tServ - Statistical Software
Generalized Additive Models A clear and concise introduction to GAMs
Russ Lenth's power and sample-size interactive page

Emili Garcia-Berthou's Statistical Ecology Links

Animaux : Structures et fonctions

21 Février 2009,

Publié par JMB

Merci au Pr. Antoine Morin de l'Université d'Ottawa, pour ces notes de cours disponibles sur Internet. Antoine Morin ne dispense plus ce cours. Ces notes ne sont plus mises à jour depuis 2003, mais elles retent encore très valables :

Cycles biologiques, développement, architecture, anatomie fonctionnelle, métabolisme et adaptations aux différents environnements des principaux types d'animaux.
Cliqez ici

Le département de Biologie de l'Université d'Otawwa (Canada) met aussi en libre service de nombreuses notes de cours : ici

Conseils avant d'entreprendre un Doctorat ou un Master

21 Février 2009,

Publié par JMB

Jeune porc-épic âgé d’une semaine environ (photo D. Berteaux)

Voici quelques conseils de mon collègue et ami Dominique Berteaux, chercheur au Québec. Je les partage totalement. Donc, avant d'entreprendre des études de 3ième cycle, lisez bien ce qui suit (c'est valable pour tous les étudiants, quel que soit le pays !).
Remarque :  la maitrîse dure 2 ans au Canada, mais ce n'est pas vraiment équivalent à notre Master français, puisqu'au Canada, ces 2 ans correspondent surtout à un travail de recherche. Alors qu'en France, sur 2 ans de Master (M1 et M2 recherche), l'étudiant n'entreprend qu'un stage  de recherche de 6 à 8 mois en fin de M2  !

"Conseils aux nouveaux étudiants :

La maîtrise et le doctorat sont des étapes importantes, exigeantes, et parfois déstabilisantes à cause de la grande liberté laissée aux étudiants et des nombreuses décisions à prendre au cours des travaux de recherche.

Avant de vous engager dans des études graduées (M2 et doctorat), pensez à ce qui suit :

  • Comment allez-vous financer vos études ? Une maîtrise dure généralement 2 ans et un doctorat 4 ans (3 ans en France). Comment allez-vous vivre pendant ces années ? La plupart des étudiants qui s’engagent dans des études graduées obtiennent des bourses du gouvernement canadien, du gouvernement québécois, ou d’autres sources.
  • Pourquoi voulez-vous faire des études graduées ? La principale cause d’échec dans les études graduées est le manque de motivation. Deux (mauvaises) raisons communes de faire des études graduées sont la peur d’affronter le marché du travail après le bacc (= Licence). et la pression sociale. La seule bonne raison de faire des études graduées est une forte volonté d’acquérir une formation de haut niveau en recherche ou conservation, en étant prêt à investir beaucoup de temps et d’énergie dans cette formation.
  • Avez-vous discuté avec des étudiants en maîtrise ou doctorat ? Avez-vous une idée claire de ce que les études graduées représentent, de la manière dont votre travail sera organisé pendant ces années ?
  • Si vous voulez travailler avec des animaux sur le terrain, avez-vous déjà acquis une expérience pertinente ? Avez-vous des raisons de penser que vous serez à l’aise à vivre des mois dans la nature, dans un confort parfois minime ?
  • Les études graduées en écologie comportent une partie de travail de terrain (15-30% du temps), mais aussi beaucoup de travail intellectuel. C’est en général l’effort intellectuel qui détermine le plus la qualité du mémoire de maîtrise ou de la thèse de doctorat (c'est vrai quelle que soit la discipline)
     

Quand les études graduées se déroulent bien, elles restent souvent dans la mémoire comme les années les plus excitantes de la vie !
Si vous êtes motivés par votre sujet de recherche et persévérent, alors le résultat final ne peut être qu'excellent ! N'hésitez pas, lancez-vous ! 

Des conseils supplémentaires sont disponibles dans le document "Smooth Sailing" (PDF). Bien que ce document ait été produit spécifiquement pour les étudiants de McGill, beaucoup de conseils ont une valeur générale et seront utiles pour tous les étudiants.

GENETIC STUDIES OF AGING AND LONGEVITY IN MODEL ORGANISMS

20 Février 2009,

Publié par JMB

GENETIC STUDIES OF AGING AND LONGEVITY IN MODEL ORGANISMS


By Ji Yuan

(August 2004) Original article : link


Aging can be characterized as:
(1) an inevitable consequence of being a multicellular organism;
(2) associated with a random, passive decline in function;
(3) leading to a global loss of homeostasis (the state of sustained equilibrium in which all cells, and all life forms, exist) over time; and
(4) mortality increasing with age [1].
Age is not a disease, but it does predispose an organism to a variety of diseases [2], in the case of humans, this includes heart disease, arthritis, osteoporosis, diabetes, cancer and Alzheimer’s.

Achieving longevity is thought to be caused by a combination of factors. Possessing longevity-enabling genes, lacking disease-predisposing genetic variations and appropriate health-related behavior are all thought to contribute to long life [3] . Therefore, understanding of the genetics of aging and longevity should lead to the discovery of genes and ultimately drugs that slow down the aging process and facilitate people’s ability to delay and perhaps escape age-associated diseases.

Humans’ relatively long life expectancy makes them less attractive as subjects for longevity research. Using short-lived organisms to discover life-span-altering genes is much more feasible. This paper describes the current state of aging and longevity research with model organisms.


Genetic Model Systems

The major genetic model systems used in aging research are those of the filamentous fungus Podospora anserine, baker’s yeast Saccharomyces cerevisiae, the roundworm Canenorhabditis elegans (C. elegans), the fruit fly Drosophila melanogaster (D. melanogaster), and the common mouse.

These model systems have many advantages for genetic dissection of aging and longevity mechanisms. They are small, easy to maintain, and have a short life span. For instance, life cycle of yeasts and worms is only few days. This allows experiments to be concluded within weeks of their initiation. In addition, there is significant homology between the human genome and those of simpler organisms. About one-fifth of human disease genes that have been positionally cloned possess yeast homologues, reflecting a remarkable degree of genetic conservation [4].

Several genetic methodologies have been used to study aging in these organisms [2]. Mutagenesis is a method that affects the expression of genes or the structure of gene products by altering of DNA sequences using physical or chemical treatment, followed by screening for individuals that possess the resultant phenotypes (visible characteristics and/or behavior that result from the interaction of an organism’s genotype and the environment). Molecular genetics strategies are similar except that they target known genetic loci that are thought to be involved in expressing the phenotype of interest. Quantitative trait loci (QTL) analysis encompasses a family of techniques that are used to zero in on the location of genes responsible for the variation in a particular phenotype. Selective breeding is used to progressively comb together the genetic variants in a population that are responsible for a particular trait by choosing individuals with the most extreme phenotypic expression for breeding. These genetic methodologies have now identified 35 cloned genes that determine longevity in model organisms. These genes encode a wide variety of proteins with a variety of functions, but they can be categorized into four broad physiological processes that play a role in aging: metabolic control, resistance to stress, gene dysregulation, and genetic stability. Insulin is the major hormone controlling critical energy functions. Below is an example of an insulin-like signaling pathway that plays a role in the control of metabolism, development and longevity in C. elegans.


Insulin-like signaling pathway

Studies of long-lived mutants of the nematode C. elegans have contributed significantly to the progress made in the study of aging during the last decade. An example of what has been learned is the discovery of an insulin-like signaling pathway that regulates longevity and metabolism in C. elegans [5].

 

insulinlikepath[2]-1.gif
Figure 1: An insulin-like signaling pathway may regulate longevity in C. elegans. High concentration of insulin-like ligands activate AGE-1 and PDK-1, which activate AKT-1 and AKT-2. These enzymes negatively regulate expression of DAF-16, which is involved in dauer arrest.

 


After embryonic development and hatching, the worms move through a series of four larval stages (L1-L4) before reaching adulthood. If they encounter particular environmental stress, worms will enter the dauer larval stage, which allows worms to survive adverse conditions. When favourable environmental conditions arise, dauer larvae resume development and proceed to L4 larval stage and subsequently to adulthood (Figure 2). In dauer state, worms can survive up to 6 months, which is much longer than adult worm life span (2-3 weeks). The increase in lifespan of the dauer state is not entirely due to reduced metabolism, but also due to increased levels of antioxidant enzyme and stress-resistance proteins [6]. The insulin-like pathway is part of a global endocrine system that controls whether the worms grow reproductively or arrest at the dauer stage.

During the time of dauer formation, numerous dauer formation (daf) genes are active and some of them play roles in determining the two alternative developmental fates (dauer or L3 stage) of C. elegans. These regulatory genes were identified by two general classes of mutants: dauer defective and dauer constitutive mutants. Mutants that possess Dauer constitutive genes such as daf-2 and age-1 which constitute components of the C. elegans insulin signaling pathway live 2 to 3 times longer than wild type [8-10]. Conversely, daf-16 dauer defective mutants suppress the increase in longevity caused by daf-2 and age-1 mutants. Based on previous genetic studies, several dauer genes have been ordered into an insulin-like signaling pathway [5,11-15]. Under reproductive growth conditions, high daf-2 receptor signaling activates age-1 and pdk-1 which in turn, activates the akt-1 and -2 kinases, which negatively regulate daf-16 activity. Inactivated daf-16 fails to further activate the genes necessary for dauer arrest and long life span or repress the genes that inhibit reproductive growth and short life span [7]. Under dauer inducing conditions, these kinase cascades are inactive, so then active daf-16 represses genes required for reproductive growth and short life span, and/or activate genes necessary for dauer arrest and long life span [7]. (Figure 1)

 

wormcycle.gif

Figure 2. The life cycle of C. elegans can be interupted by the dauer stage if environmental conditions are not favourable.

 


In addition to metabolism, the C. elegans insulin pathway regulates free radical protection [16]. Moreover, the insulin pathway in worm aging may be related to the longevity increase caused by caloric restriction in mammals [17]. Caloric restriction in mammals may cause a decline in insulin-like signaling that induces a partial diapause state [18], like that induced in weak daf-2 and age-1 mutants.

Recently, two research group described mutants of genes that modulate pathways homologous to insulin signaling pathways in humans and increase life span of D. melanogaster. A mutation of the insulin-like receptor gene [19], which is homologous to the C. elegans daf-2 gene, and a mutation of the D. melanogaster gene chico 20, which participates in an insulin-like signaling pathway, are associated with a significant increase in life span. Thus, the role of insulin-like signaling pathways appears to be evolutionarily conserved in a number of species, suggesting the importance of investigating such pathways and their relation to aging and longevity in humans.


Conclusion

Genetic studies in simpler organisms demonstrate that specific genes have potent influences on life span. These findings provide a framework for understanding the factors by which life span is determined in lower organisms. More importantly, organism models provide interesting phenotypic characteristics and candidate pathways to be studied in relation to longevity, such as parameters of metabolic control, stress resistance and genetic instability. However, investigation of human homologues of these genes would naturally be more complicated because aging and susceptibility to diseases associated with aging in human is influenced by multiple genes as well as environment factors.


Glossary

1. Mutagenesis - The production of either random or specific mutations in a piece of cloned DNA. Typically, the DNA will then be reintroduced into a cell or an organism to assess the results of the mutagenesis.

2. Quantitative Trait Loci - Continuous traits are often measured and given a quantitative value. Therefore, they are often referred to as quantitative traits, and the area of genetics that studies their mode of inheritance is called quantitative genetics. Many human phenotypes such as IQ, learning ability and blood pressure are quantitative traits. These traits are controlled by multiple genes, each segregating according to Mendel’s laws.

3. Metabolic Control - Mechanisms by which the chemical reactions that occur in a living cell are controlled.


References

1. Helfand, S.L. & Rogina, B. Molecular genetics of aging in the fly: is this the end of the beginning? Bioessays 25, 134-41 (2003).

2. Jazwinski, S.M. Aging and longevity genes. Acta Biochim Pol 47, 269-79 (2000).

3.Perls, T., Kunkel, L. & Puca, A. The genetics of aging. Curr Opin Genet Dev 12, 362-9 (2002).

4. Bassett, D.E., Jr. et al. Genome cross-referencing and XREFdb: implications for the identification and analysis of genes mutated in human disease. Nat Genet 15, 339-44 (1997).

5. Kimura, K.D., Tissenbaum, H.A., Liu, Y. & Ruvkun, G. daf-2, an insulin receptor-like gene that regulates longevity and diapause in Caenorhabditis elegans. Science 277, 942-6 (1997).

6.Murakami, S. & Johnson, T.E. A genetic pathway conferring life extension and resistance to UV stress in Caenorhabditis elegans. Genetics 143, 1207-18 (1996).

7. Finch, C.E. & Ruvkun, G. The genetics of aging. Annu Rev Genomics Hum Genet 2, 435-62 (2001).

8. Dorman, J.B., Albinder, B., Shroyer, T. & Kenyon, C. The age-1 and daf-2 genes function in a common pathway to control the lifespan of Caenorhabditis elegans. Genetics 141, 1399-406 (1995).

9. Kenyon, C., Chang, J., Gensch, E., Rudner, A. & Tabtiang, R. A C. elegans mutant that lives twice as long as wild type. Nature 366, 461-4 (1993).

10. Larsen, P.L., Albert, P.S. & Riddle, D.L. Genes that regulate both development and longevity in Caenorhabditis elegans. Genetics 139, 1567-83 (1995).A phosphatidylinositol-3-OH kinase family member regulating longevity and diapause in Caenorhabditis elegans. Nature 382, 536-9 (1996).

11. Morris, J.Z., Tissenbaum, H.A. & Ruvkun, G.

12. Ogg, S. et al. The Fork head transcription factor DAF-16 transduces insulin-like metabolic and longevity signals in C. elegans. Nature 389, 994-9 (1997).

13. Ogg, S. & Ruvkun, G. The C. elegans PTEN homolog, DAF-18, acts in the insulin receptor-like metabolic signaling pathway. Mol Cell 2, 887-93 (1998).

14. Paradis, S. & Ruvkun, G. Caenorhabditis elegans Akt/PKB transduces insulin receptor-like signals from AGE-1 PI3 kinase to the DAF-16 transcription factor. Genes Dev 12, 2488-98 (1998).

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(Art by Jen Philpot)