Complex sex-linked fusion heterozygosity in the Australian huntsman spider Delena cancerides (Araneae: Sparassidae)

In the vast majority of spider species studied to date, the karyotype is homogeneous in morphology and exclusively telocentric. The sex-determining system consists of one to three X chromosomes in the male and, correspondingly, two to six in the female. This is the case in species of huntsman spiders belonging to the genera Heteropoda (2n=40+3X), Isopoda, Olios, and Pediana (2n=40+3X) and some populations of the colonial species Delena cancerides (2n=40+3X). In other populations of D. cancerides, wholesale fusion of the karyotype has occurred, reducing the standard huntsman karyotype of 43 telocentric chromosomes to 21 metacentrics and 1 telocentric. Eight of the centric fusion products, including an X-autosome fusion, are maintained in the heterozygous condition in males and, with the single telocentric, form a chain of nine chromosomes at meiosis. The two complexes comprising the chain behave as neo-X and neo-Y chromosomes, and thus the ancestral X₁X₂X₃X₁X₁X₂X₂X₃X₃ sex-determining system has been converted to a system of six X and four Y chromosomes in the male and twelve X chromosomes in the female. Since sex-linked complex heterozygosity is also found in a number of species of social termites, it is suggested that such heterozygosity may have adaptive significance for a colonial lifestyle. Breakdown products of the chain of nine are present in specimens of D. cancerides from Canberra and these appear to represent hybrid products between the 2n=22 and 2n=43 forms. Hybridisation may also have been involved in the origin of the chain-forming races.     

Inhibition of carcinogen-induced cellular transformation of human fibroblasts by drugs that interact with the poly(ADP-ribose) polymerase system. Initial evidence for the development of transformation resistance

Two types of interactions of 13 drugs with human fibroblasts were determined: I50 of nuclear poly(ADP-ribose) polymerase, as assayed with isolated nuclei in vitro, and the non-toxic concentration of drugs that prevented carcinogen-induced cell transformation of intact fibroblasts (RCF1). In general, RCF1 was much lower than I50, and one antitransformer did not inhibit the enzyme in vitro, indicating that low-affinity enzyme inhibitory sites appear to play no role in the mechanism of prevention of cell transformation. Two enzyme inhibitors, caffeine and 1-methylnicotinamide, exhibited no antitransforming activity. Benzamide when applied in population doubling 1 induced resistance to cell transformation in population doubling 6 by carcinogens added at this stage.     

The effect of nematode parasitism on the osmolality and major cation concentration in the haemolymph of three larval mosquito species

Parasitism by a mermithid nematode, Romanomermis culicivorax, causes severe depletion of haemolymph carbohydrates and proteins in mosquito larvae. We undertook a study to determine if haemolymph osmolality and cation concentrations were affected also by mermithid parasitism. The haemolymph osmolality of R. culicivorax-infected and control Aedes taeniorhynchus and Culex pipiens fourth-instar larvae was not significantly different. However, the haemolymph osmolality decreased significantly in infected Anopheles quadrimaculatus. Each mosquito species demonstrated significant alterations in the haemolymph concentration of at least one cation when infected although the cation concentrations affected differed for each species. The changes observed were statistically significant but the magnitude of change was not great. Overall, despite the severe nutritional burden of the mermithid nematode, these species of mosquito larvae can continue to maintain osmoregulation.     

The uptake and metabolism of methylamine by N2-fixing cyanobacteria

The cyanobacteria Anabaena variabilis and Nostoc CAN showed a biphasic pattern of ¹⁴CH₃NH ₃ ⁺ uptake at external pH values of 7.0 and 9.0. The initial phase of uptake, which was independent of metabolism of ¹⁴CH₃NH ₃ ⁺ , was attributed to uptake via a CH₃NH ₃ ⁺ (NH ₄ ⁺ ) transport system at pH 7.0 and probably to passive diffusion of uncharged CH₃NH₂ and trapping by protonation at pH 9.0. The second slower phase of uptake was attributed to metabolism of CH₃NH ₃ ⁺ via glutamine synthetase to form -methylglutamine which accumulates. Anabaena cylindrica showed an initial rapid uptake at pH 7.0 and pH 9.0 but metabolism of ¹⁴CH₃NH ₃ ⁺ was undetectable at pH 7.0 and was barely detectable at pH 9.0. Pretreatment of A. variabilis with l-methionine-d,l-sulphoximine to inactivate glutamine synthetase, inhibited the second phase of ¹⁴CH₃NH ₃ ⁺ uptake at both pH 7.0 and pH 9.0 and the accumulation of -methylglutamine but had no effect on the first phase of uptake. Following transfer of A. variabilis to darkness the initial phase of ¹⁴CH₃NH ₃ ⁺ uptake at pH 7.0 and 9.0 was unaffected but the subsequent metabolism via glutamine synthetase was inhibited.Abbreviations MSX l-methionine-d,l-sulphoximine - GS glutamine synthetase     

Close linkage between X-linked ectodermal dysplasia and a cloned DNA sequence detecting a two allele restriction fragment length polymorphism in the region Xp11-q12

Summary EDA (ectodermal dysplasia, anhidrotic) is an X-linked recessive disorder characterized by hypohidrosis, hypoor anodontia, and hypotrichosis. A possible linkage between the gene for EDA and a number of restriction fragment length polymorphisms (RFLPs) spread over the X chromosome was investigated in two Danish families segregating EDA. No recombination between the gene for EDA and our probe pTAK8, which detects a two allele polymorphism in the region Xp11-q12, was found in nine informative meiotic events (seven of which are phase known), giving a maximal lod score of 2.41 at a recombination fraction of 0.00. This juxtacentromeric location of the gene for EDA agrees well with the linkage data obtained with the other markers used in this study.     

Forest living baboons in Uganda

The climate and vegetation of the study area is described: in many ways it was not typical of baboon habitats in Uganda, but had the advantage and interest of offering a clear choice of a variety of habitats. The structure and composition of the baboon population is described Ndashthis was a rapidly expanding population with no seasonality in breeding. Their use of the