A clustered set of three Sp-family genes is ancestral in the Metazoa: evidence from sequence analysis, protein domain structure, developmental expression patterns and chromosomal location.

BACKGROUND: The Sp-family of transcription factors are evolutionarily conserved zinc finger proteins present in many animal species. The orthology of the Sp genes in different animals is unclear and their evolutionary history is therefore controversially discussed. This is especially the case for the Sp gene buttonhead (btd) which plays a key role in head development in Drosophila melanogaster, and has been proposed to have originated by a recent gene duplication. The purpose of the presented study was to trace orthologs of btd in other insects and reconstruct the evolutionary history of the Sp genes within the metazoa. RESULTS: We isolated Sp genes from representatives of a holometabolous insect (Tribolium castaneum), a hemimetabolous insect (Oncopeltus fasciatus), primitively wingless hexapods (Folsomia candida and Thermobia domestica), and an amphipod crustacean (Parhyale hawaienis). We supplemented this data set with data from fully sequenced animal genomes. We performed phylogenetic sequence analysis with the result that all Sp factors fall into three monophyletic clades. These clades are also supported by protein domain structure, gene expression, and chromosomal location. We show that clear orthologs of the D. melanogaster btd gene are present even in the basal insects, and that the Sp5-related genes in the genome sequence of several deuterostomes and the basal metazoans Trichoplax adhaerens and Nematostella vectensis are also orthologs of btd. CONCLUSIONS: All available data provide strong evidence for an ancestral cluster of three Sp-family genes as well as synteny of this Sp cluster and the Hox cluster. The ancestral Sp gene cluster already contained a Sp5/btd ortholog, which strongly suggests that btd is not the result of a recent gene duplication, but directly traces back to an ancestral gene already present in the metazoan ancestor.

Development of embryonic membranes in the silverfish Lepisma saccharina linnaeus (insecta: Zygentoma, Lepismatidae).

Development and fate of embryonic membranes in the silverfish Lepisma saccharina was examined throughout embryogenesis. The amnioserosal folds first arise as serosal folds that are completed by the later addition of the amnion from the embryo's margins as in archaeognaths. The close link between production of the amnion and formation of the folds should not be assigned to Dicondylia but to Pterygota as an autapomorphy. During fold formation, folding of embryonic membranes beneath the embryo is less extensive and the ventral cupping of the embryo plays a larger role comparable to that occurring in archaeognath embryos. In L. saccharina, the embryonic membrane pore (the amniopore) varies in its manner of closure, either by complete fusion of serosal folds or by formation of a serosal cuticular plug between them as in archaeognaths. Although, in many aspects of its embryogenesis, L. saccharina retains the primitiveness of archaeognaths, its amnioserosal folds persist and are well integrated into its embryogenesis as the amnioserosal fold-amniotic cavity system is established and as occurs in many pterygote embryos; this may be thus regarded as an autapomorphy of Dicondylia.

Distant non-chemical communication in various biological systems.

Communication is a natural ability of all living systems. It is very likely that various types of communication were evolved during evolution. While the communication by means of chemicals, direct contact or via organs of sense is under intensive study for a long time, alternative ways of interaction are still considered debatable, This review covers the topic of physically mediated communication in various biological systems.

Effects of size and temperature on developmental time.

Body size and temperature are the two most important variables affecting nearly all biological rates and times. The relationship of size and temperature to development is of particular interest, because during ontogeny size changes and temperature often varies. Here we derive a general model, based on first principles of allometry and biochemical kinetics, that predicts the time of ontogenetic development as a function of body mass and temperature. The model fits embryonic development times spanning a wide range of egg sizes and incubation temperatures for birds and aquatic ectotherms (fish, amphibians, aquatic insects and zooplankton). The model also describes nearly 75% of the variation in post-embryonic development among a diverse sample of zooplankton. The remaining variation is partially explained by stoichiometry, specifically the whole-body carbon to phosphorus ratio. Development in other animals at other life stages is also described by this model. These results suggest a general definition of biological time that is approximately invariant and common to all organisms.

Persistency of bioactive fractions of Indian plant, Polygonum hydropiper as an insect feeding deterrent.

An improved extraction procedure resulted into a six-fold yield of bioactive fraction than the usual extraction method with a high per cent of feeding deterrence against 3rd instar larvae of Spilarctia obliqua and Spodoptera litura. The effective concentration (EC50) of PH-2 was 4321 and 4155 ppm against the two insects. No loss in feeding deterrency was recorded when the bioactive ether fraction, PH-2 was exposed to sunlight for 6 h.

The DNA puff BhB10-1 gene encodes a glycine-rich protein secreted by the late stage larval salivary glands of Bradysia hygida.

We present the molecular characterization of a gene of Bradysia hygida DNA puff B10 whose temporal expression in the salivary gland correlates with the puff expansion. The transcription unit of this gene, named BhB10-1, was mapped in a 2-kb EcoRI genomic fragment that is amplified in the salivary gland of late fourth instar larvae. Its 1.3-kb transcript undergoes poly-A tail shortening during development, indicating that post-transcriptional controls as well as transcription activation are involved in the temporal regulation of the BhB10-1 gene. Analysis of the deduced amino acid sequence from the cDNA indicates that the BhB10-1 protein is a glycine-rich secretory protein. A BhB10-1-fusion protein expressed in bacteria was used to raise polyclonal antibodies. Using an immunopurified antibody, we identified the product of the DNA puff BhB10-1 gene as a 23-kDa polypeptide that is produced mainly by the salivary gland regions S1 and S3 and is present in the saliva of late larvae. This is the first direct identification of a protein encoded by a DNA puff amplified gene.