Chitinases have an indispensable function in chitin metabolism and are well characterized in numerous insect species. Although the diamondback moth (DBM) Plutella xylostella, which has a high reproductive potential, short generation time, and characteristic adaptation to adverse environments, has become one of the most serious pests of cruciferous plants worldwide, the information on the chitinases of the moth is presently limited. In the present study, using degenerated polymerase chain reaction (PCR) and rapid amplification of cDNA ends-PCR strategies, four chitinase genes of P. xylostella were cloned, and an exhaustive search was conducted for chitinase-like sequences from the P. xylostella genome and transcriptomic database. Based on the domain analysis of the deduced amino acid sequences and the phylogenetic analysis of the catalytic domain sequences, we identified 15 chitinase genes from P. xylostella. Two of the gut-specific chitinases did not cluster with any of the known phylogenetic groups of chitinases and might be in a new group of the chitinase family. Moreover, in our study, group VIII chitinase was not identified. The structures, classifications and expression patterns of the chitinases of P. xylostella were further delineated, and with this information, further investigations on the functions of chitinase genes in DBM could be facilitated.

Cephalocarida is a rare and poorly known class of small benthic crustaceans, consisting of only eleven species belonging to five genera. Thus far, only one species (Hutchinsoniella macracantha) has been studied at molecular level. We report the partial sequences of two phylogenetically important mitochondrial genes (Cytochrome c Oxidase I and Cytochrome b) from the newly discovered Mediterranean species, Lightiella magdalenina. The genetic relationships between the two cephalocarid species are discussed.

This article reviews the main trends in the evolution of the vertebrate axial skeleton, with special focus on mammals. The structure of vertebrae is exposed according to traditional and current conceptions and several examples of species-specific and topography-specific adapta tions are given. The relationships between stature and the anatomy of the bony girdles surrounding the spine are discussed. Hypotheses on the influence of gravity on axial morphogenesis are formulated.

We examined 3747 teeth from 134 hares (Lepus sp.) collected at 46 sites in Israel to test whether variation in epigenetic occlusal characters was linked to ecogenetic or phylogenetic factors. Collection sites encompassed a wide range of ecogeographical and climatic regimes. We compared data from Israeli hares with occlusal characters of 160 cape hares L. capensis from East Africa and 68 brown hares L. europaeus from central Europe. Only three teeth (I1, I2, M3) did not show occlusal variation. Thirty-eight occlusal characters were derived from dental variants by dichotomous (0/1) scoring. Absence of association of character states among characters of single teeth indicated a lack of morphotypes. Epigenetic differentiation among hares from northern, central and southern Israel, and the two East African, and two central European samples, was revealed by pairwise C. A. B. Smith's ‘mean measures of divergence’ (MMD), based on frequencies of character states. Cluster analyses of MMD values revealed little epigenetic differentiation between northern and southern Israeli hares, but greater differentiation between central European and East African hares. Concordance of the MMD matrix with linear geographical distances among sampling regions was demonstrated by a Mantel test. No frequencies of character states exhibited significant changes across the climatic parameters among hares from northern and southern Israel. But the individual folding index, which expresses the degree of enamel on the occlusal surface, slightly decreased from north to south. Our results support a phylogenetic interpretation of occlusal character variation. Despite distinct differences in external appearance, hares from northern and southern Israel probably comprise a single species that encompasses two closely related geographical populations with a probable area of overlap. Israeli hares are intermediate between European brown hares and East African cape hares, with a slightly closer relationship to the cape hares.

Mankind uses some 40 species of animals as domestic livestock to meet our needs for food, clothing, power, etc. Within these species, there are in total some 4,500 breeds that are referred to as the global animal genetic resources. Each breed comprises a unique set of genes. More than 30% of breeds are estimated to be at risk of extinction, and many more, particularly in developing countries, are threatened by inefficient utilization. The Food and Agriculture Organization of the United Nations has been mandated by its member nations to manage the global animal genetic resources, and major progress has been made in the last few years. However, resources are limited, and priorities will have to be set for breed conservation, for breed development programmes and for evaluation studies. Breeds that are taxonomically distinct should be favoured for conservation, the objective being to maintain maximum genetic diversity of each livestock species. Genetic distances and phylogenetic diversity provide the best available objective criterion, and microsatellites are the current markers of choice for obtaining the genetic data. Microsatellite-based genetic distances will describe breed similarities due to common ancestry, but cannot account for consequences of artificial or natural selection. Phylogenetic trees for 11 water buffalo populations in southeast Asia, constructed using 25 polymorphic protein coding loci or 21 microsatellite loci, show differences in both topology and branch lengths, but the microsatellite tree is a better representation of the similarities due to common ancestry. Thus phylogenetic diversity, based on microsatellite loci, should be used as an initial guide in making conservation decisions for livestock breeds.