The core of lifehistory theory

When Charles Darwin travelled with the H.M.S. Beagle to Tierra del Fuego and the Falkland Islands in 1834, he was surprised to find, on counting the eggs of a large white Doris (a sea slug), how extraordinarily numerous they were. The slugs produce their eggs as a long ribbon, rolled up in a cone, and adhered to the rock. The inquisitive naturalist, extrapolating from a part of the structure, estimated the total number of eggs in one spire to be at least 600000. Yet the animal itself was...

Genomic approaches to lifehistory patterns an appraisal

Genomic analyses of life histories, as reviewed in this chapter, have revealed a number of molecular principles underlying regulation and determination of key life-history events. These can be summarized as follows. Environmental information (food, crowding, light, daylength, temperature) often modulates life-history traits and this is the basis of phenotypic plasticity. In animals, such information is typically processed by the nervous system, then translated into a hormonal signal, which acts...

Longevity and aging

Insulin Signalling Pathway

The nematode C. elegans has developed into a classical model for the study of aging. Most of this research is motivated by a possible connection with aging in humans, but the new insights accumulated over the last few years are of equal relevance to ecology and life-history theory. It also appears that the properties of the molecular machinery regulating aging are shared with Drosophila and are even conserved across the whole animal kingdom. The main reason why C. elegans became a model for...

Metallothionein and associated systems

Metallothionein

Metallothionein is a peculiar protein with an extremely high affinity for free metal ions such as Zn2 , Cd2 , and Cu . In the presence of sufficient metallothionein the free concentrations of these metals in solution are reduced to the picomolar range. Interestingly, iron is not bound by metal-lothionein but instead has its own pathways of uptake and intracellular transport, involving ferro-transferrin and ferritin. As we will see below, changes in iron trafficking are part of the general...

Info

Distribution Whole Genome Duplication

Figure 3.25 Functional analysis of the Arabidopsis genes predicted from the genome sequence, showing the similarities between Arabidopsis functional gene categories and bacterial genomes E. coli and Synechocystis, a cyanobacterium and those of yeast, nematode, and fruit fly. The y axis indicates the fraction of Arabidopsis genes in a functional category showing a BLAST match with the respective reference genome. The right to use this figure provided courtesy of members of the Arabidopsis Genome...

A B C D E F G H

Figure 2.5 Example of results from a differential screening approach applied to clones from a subtracted library sexual versus asexual strains from the freshwater planarian G. tigrina . Clones arrayed on nylon membranes were selected randomly from the subtracted library top panels to study upregulation, and the reverse-subtracted library bottom panels to study downregulation. The dot-blots were then hybridized to labelled probes prepared from the subtracted left-hand panels and...

Stress and the ecological niche

Ecological Niche Graph

Even the most casual observer of natural systems will note that many species tend to occupy a characteristic place in nature. The idea is demonstrated most vividly by gradient studies, for example the distribution of plants on a salt marsh, where each species tends to be limited to a certain zone by a combination of soil texture, redox potential, salt, and lime. Ecologists have invented the concept of an ecological niche to organize their thoughts about the ways in which organisms fit into...

Reconstruction of functions from environmental genomes

An exciting new development in microbial geno-mics is the exploration of communities by isolating large fragments of DNA directly from the environment and cloning them into vectors such as BACs, followed by probing, sequencing, or screening for functions Ball and Trevors 2002 Handelsman 2004 Riesenfeld et al. 2004a Tiedje and Zhou 2004 Allen and Banfield 2005 DeLong 2005 Schleper et al. 2005 . This approach, designated community genomics or metagenomics, allows insight into microbial diversity,...

Saccharomyces Cerevisiae

Life Cycle Saccharomyces Cerevisiae

White rot, in fallen trees, on forest floor, degrades lignin Sources and Kellis et al. 2003, 2004 . Sources and Kellis et al. 2003, 2004 . or white rot fungus, which is found commonly on dead trees and wood fragments on the forest floor. To date, white rot fungus is the only basidomycete mushroom-forming fungus that has had its genome sequenced Martinez et al. 2004 . White rot owes its name to the fact that the fungus 'bleaches' wood by degrading the brown-coloured lignin, rendering the white...