Steroid sulphatase levels in XX males,including observations on two affected cousins

Summary Quantitative assays of steroid sulphatase in XX males have shown that some individuals have two functional loci, and others only one. Two affected cousins, who cannot share the same X-chromosome, nevertheless have male levels of steroid sulphatase, suggesting functional abnormality of the X chromosome.The hypothesis is advanced that these and other unusual features of X-chromosome function in some XX males, could be explained if such cases were due to an autosomal mutation, exercising its effect by causing abnormal inactivation of a subterminal area of Xp which normally escapes the inactivation process.     

Aerial web-weaving spiders: Linking molecular and organismal processes in evolution

Aerial web-weaving spiders display a wide variety of foraging behaviors that can be tied to the evolution of one family of proteins, the silks. In some cases, the physical structure and mechanical properties of silks alone determine the ecology of spiders: the habitats in which they forage, the prey they capture and their subsequent reproductive success. Future studies that integrate research on the physical structure of silks, the molecular genetics of silk synthesis and the foraging ecology of spiders in primitive and derived phylogenetic groups could reveal how molecular and organismal processes interact in evolution.     

Partial characterization of a Trypanosoma cruzi-released decomplementing factor

Trypanosoma cruzi releases a factor (SCAF) when grown in vitro which decomplements normal mouse, human, and guinea pig sera. The production and potency of SCAF was dependent on the density of cultured parasites, parasite viability and proliferative capacity, and duration of culture. The in vitro interaction between SCAF and serum complement (C') occurred rapidly and was complete within 30 min of mixing. The administration of SCAF to normal mice resulted in up to 50% reduction in hemolytic C' activity, whereas SCAF had no effect on the C' levels in mice infected wit T. cruzi for more than 10 days. The active moiety of SCAF was shown to be a nonproteinaceous substance(s) with a molecular weight of approximately 23,000 daltons.     

Diel vertical migration in Mesocyclops edax: implications for predation rate estimates

The diel migration patterns of Mesocyclops edax and its preyin a small lake were followed in two studies separated by approximatelyone year. Gut contents of the predators were examined and selectivityindices calculated at each depth at 0100 h during 1980. Thethree principal zooplankton prey found in the guts of M. edaxwere Keratella, Kellicottia, and Bosmina. The predator and allthree major prey species exhibited unique and different dielvertical distribution and migration patterns. The complex natureof the spatio-temporal variation in prey density to which M.edax is exposed, demonstrates the dangers of using selectivityindices without knowledge of the distribution patterns of bothpredator and prey. An increase in vertebrate predation pressurefrom one year to the next is thought to be responsible for anincrease in the abundance of small zooplankton species, thedisappearance of two out of three of the large zooplankton species,and the onset of a pronounced nocturnal migration pattern inthe third large species. ¹Present address: Biology Department, Williams Hall #31, LehighUniversity, Bethlehem, PA 18015, USA     

Stereospecific activity of 1-O-alkyl-2-O-acetyl-sn-glycero-3-phosphocholine and comparison of analogs in the degranulation of platelets and neutrophils

1-O-Hexadecyl-2-O-acetyl-$\text{sn}$-glycero-3-phosphocholine (platelet activating factor) stimulated the degranulation of rabbit platelets and human neutrophils, whereas the enantiomer, 3-O-hexadecyl-2-O-acetyl-$\text{sn}$-glycero-1-phosphocholine, was inactive. The analogs compared had the following relative potencies in degranulating platelets and neutrophils: 1-O-hexadecyl-2-O-acetyl-$\text{sn}$-glycero-3-phosphocholine > 1-O-hexadecyl-2-O-ethyl-$\text{sn}$-glycero-3-phosphocholine >$\text{rac}$-1-O-octadecyl-2-O-ethylglycero-3-phosphocholine = 1-O-hexadecyl-2-O-methyl-$\text{sn}$-glycero-3-phosphocholine >$\text{rac}$-1-O-dodecyl-2-O-ethyl-glycero-3-phosphocholine. The deacetylated compound, 1-O-hexadecyl-2-lyso-$\text{sn}$-glycero-3-phosphocholine, and 1-O-hexadecyl-2,2-dimethylpropanediol-3-phosphocholine were inactive. The active analogs selectively desensitized the response to each other in the neutrophils. It is suggested that these compounds may activate cells through interaction with a stereospecific receptor.     

Mouse DNA methylase: methylation of native DNA.

An improved method of purification of DNA methylase from Krebs II ascites cells is reported. The enzyme sediments at 8.3 S on glycerol-gradients and a major band on SDS polyacrylamide gel electrophoresis has a molecular weight of 184 000. Aggregation occurs at low salt and this may interfere with enzymic activity. The preferred double stranded DNA substrate is that rendered partially unmethylated by an in vitro repair mechanism or by isolation from methionine starved cells. Methylation of native partially methylated DNA is favoured under conditions of low salt and high temperature; conditions which encourage 'breathing' of the DNA. Methylation of native, unmethylated DNA also involves breathing but results in formation of a salt resistant tight binding complex between the enzyme and the DNA.     

Optimum interaction of sterol side chains with phosphatidylcholine.

The specificity of the interaction between the cholesterol side chain and egg phosphatidylcholine was precisely defined by examining the effect of three new analogues of cholesterol with modified side chains on the ordering of two steroid spin labels in liposomes. The complete side chain of cholesterol was shown to be required for maximum ordering. Sterols with side chains shorter or longer than cholesterol caused significantly less ordering.