Trees on networks: resolving statistical patterns of phylogenetic similarities among interacting proteins

Background  

Phylogenies capture the evolutionary ancestry linking extant species. Correlations and similarities among a set of species are mediated by and need to be understood in terms of the phylogenic tree. In a similar way it has been argued that biological networks also induce correlations among sets of interacting genes or their protein products.     

The microbial environment and intestinal nematode infections of Heligmosomoides polygyrus in laboratory mice

The difficulty of establishing primary infections of Heligmosomoides polygyrus (= Nematospiroides dubius) in ASH/CSI mice in the Laboratory Animal House at Royal Holloway and Bedford New College during a recent autumn and spring period was associated with a syndrome of worm distortion, together with zero or low worm establishment and reduced fecundity (eggs/female worm). The eggs produced were non-viable and the egg capsule comprised a rumpled lipid and ruptured chitin layer. The egg size and peaks of egg production were also reduced and the total egg output ceased entirely by day 28 post-infection in male mice. The syndrome was repeated when control LACA mice harbouring 'normal' infections of H. polygyrus were housed on the same source of peat bedding material as the ASH/CSI mice. An increase in H. polygyrus egg production in ASH/CSI mice, removed from the peat or treated with 0.04% oxytetracycline hydrochloride suggested that the cause of the syndrome was microbial in origin. A microbiological assay of the peat, which was the common denominator of all syndrome infections, revealed an abundance of chitinase secreting species of bacteria (Bacillaceae). Bacterial chitinase was therefore likely to rupture the chitin layer of the egg capsule producing nonviable eggs and either abnormal or no larvae. Preliminary in vitro studies using chitinase from Streptomyces griseus indicated that the hatching success of eggs of H. polygyrus was reduced as the concentration of chitinase increased.     

南瓜雌蕊与自花及远缘花粉的相互作用

南瓜柱头表面经去垢剂、蛋白酶及Con A处理后花粉不能萌发或花粉管生长受阻,Con A能专一地与柱头表面结合。柱头块加入培养液可促进花粉萌发。不同的远缘花粉授粉后在雌蕊不同部位受阻。在成熟南瓜雌蕊提取液中检测到血凝活性,凝集素可能参与雌蕊对远缘花粉的抑制。     

Computer-linked HPLC system for feedback control of fermentation substrates

Summary A data acquisition/control microcomputer system was interfaced to a commercial HPLC data transmission module. Control of substrate (ethanol) levels for four 7.5 L fermenters containing 100 g/L wet weight of the yeastCandida norvegensis was accomplished by employing intermittent, automated HPLC monitoring and a BASIC-encoded proportional integral policy for controlling substrate feed rates. Ethanol levels were maintained at 0.25, 0.50, 0.75 and 1.00% w/v.     

A trans-acting regulatory product necessary for expression of the Drosophila melanogaster 68C glue gene cluster

The mutation I(1)npr-1 is located at cytological location 2B5 on the X chromosome in Drosophila melanogaster. We have found that this mutation causes absence of the normal product of the 2B5 locus and that it has the following phenotypes: the 68C glue puff on the third chromosome does not regress when mutant salivary glands are cultured in the presence of ecdysterone; the three 68C glue protein mRNAs are not synthesized; and a transformed Drosophila strain carrying both a normal resident 68C Sgs-3 gene and an introduced functional Sgs-3 gene with only a few kb of flanking sequences expresses neither Sgs-3 RNA if the I(1)npr-1 mutation is crossed into the stock. Thus the normal product of the I(1)npr11 gene is required for regression of the 68C puff, and the I(1)npr-1 gene product allows expression of the Sgs-3 gene by interacting, either directly or indirectly, with DNA sequences near this glue protein gene.