Sib pair linkage analysis of renin gene haplotypes in human essential hypertension

Summary Although essential arterial hypertension is believed to have a strong genetic predisposition, the gene(s) responsible are unknown. The mechanisms underlying the regulation of blood pressure and experimental studies place the renin gene among the main candidate genes that need to be tested in humans. We tested the hypothesis of a linkage between the renin gene and essential hypertension using the affected sib pair method. Siblings (133 subjects, 52.1±10.9 years) from 57 families were selected for sustained hypertension (160.7 ± 22.9/99.5 ± 12.8 mmHg with 80% of patients under antihypertensive treatment), of early onset (40.7 ± 12.0 years), in the absence of obesity, diabetes mellitus, and secondary hypertension. Eight renin haplotypes were generated from three diallelic renin restriction fragment length polymorphisms (RFLPs) (TaqI, Hinfi, HindIII) located throughout the renin gene. The allelic concordance between the sib pairs was analyzed by identity by state relationships for 98 sib pairs (41 for 41 couples, 39 for 13 trios, 18 for 3 quartets). Allelic frequencies in the 57 hypertensive probands were similar to those observed among 102 hypertensive subjects studied previously. Six of eight possible haplotypes were observed, the informativity of the marker corresponded to 70% of heterozygosity. Allelic concordance for all sib pairs according to sibship size was not significantly different from that expected under the hypothesis of no linkage (t = 0.52, P = 0.15) reflecting only a small excess of renin alleles shared by the hypertensive sibs (1.44 ± 0.6 vs 1.36 ± 0.6). Likewise the linkage hypothesis was unsupported by weighted estimates to correct for possible bias due to large sibship size. Thus, the sib pair analysis suggests that the renin gene does not have a frequent role in the pathogenesis of essential hypertension; further more powerful linkage studies or other approaches will be needed to detect contributions at the renin locus to the heritability of essential hypertension.     

Occurrence of a capsule in Aeromonas salmonicida

Aeromonas salmonicida grown in a medium with excess glucose as carbon source produces both capsular and exocellular polysaccharides. The capsular polysaccharide is composed of glucose, mannose, rhamnose, N-acetylmannosamine and mannuronic acid in the molar ratios of approximately 5:3:0.75:2:1. The extracellular polysaccharide is similarly constituted, but in the molar ratios of approximately 4.75:10.5:1.5:2:1. The capsular and exocellular polysaccharides did not cross-react with monoclonal antibodies against the A-layer or the O-antigen lipopolysaccharide.     

Analysis of sibling cannibalism among pike,Esox lucius,juveniles reared under semi-natural conditions

Synopsis Sibling cannibalism in pike, Esox lucius, larvae and juveniles living in outdoor rearing ponds was studied using stomach contents analysis. For the two initial densities tested (6 and 18 larvae m^–2, equivalent to 12 and 36 larvae m^–3), cannibalism was non-existent during the larval period (13 to 35 mm total length) and was observed only during the juvenile stages. Initial density of larvae influenced both the date of first detection of cannibalistic individuals and the rate of development of cannibalism in the population. At initial stocking densities of 18 larvae m^–2 (36 larvae m^–3), cannibalism was observed from 21 days after the start of exogenous feeding (mean total length: 60 mm) onwards. At a mean total length of 100 mm and for initial stocking densities of 6 and 18 larvae m^–2, (12 and 36 larvae m^–3), the average proportions of cannibals in the populations of juveniles were 7.8% and 41.3% and the cannibals accounted for 15.5% and 65.9% of the total pike biomass, respectively. In stomachs of cannibals, young pike were the dominant prey in terms of weight. Dry weights of invertebrate-prey were lower in cannibals than in non-cannibals of similar size. Cannibalism among pike juveniles was characterized by the prey being swallowed whole and head first in the vast majority of cases. There was a strong positive correlation between predator and prey size and the mouth size of a cannibal was found to be an important constraint determining maximum victim size. The overall mean ratio of pike prey length to pike cannibal length was 66.2% and the average ratio of prey head depth to predator mouth width amounted to 87.6%. Prey size selection could be demonstrated for several length-groups of cannibals. These results are compared with the characteristics of early cannibalism in other fish species.     

The problem of the acts duration measurement in relation to the “focal-animal” technique of behavioral recording

The focal-animal technique assumes the continuous recording of the behavior of an individual during a certain time interval. The length of this interval (sampling unit) can be problematic when estimating the duration of behavioral acts. Two acts from the behavioral repertoire of the ant Leptothorax fuenteiwere focused on in this work at different ranges of temporal scales. Analyzing these acts we show the possibility of existence of a sampling artifact, in such a way that the estimates of the durations of the acts would be forced to depend upon the length of the sampling unit that is being used.     

Organisation and functions of the actV A region of the actinorhodin biosynthetic gene cluster of Streptomyces coelicolor

Summary Sequence analysis of the actVA region of the actinorhodin biosynthetic gene cluster of Streptomyces coelicolor revealed a succession of six open reading frames (ORFs), all running in the same direction and extending over 5.32 kb. The protein product of actVA-ORF1 strongly resembles that of another gene, elsewhere in the act cluster (actII-ORF2), which codes for a trans-membrane protein previously implicated in actinorhodin export from the mycelium. This suggests that the two gene products may co-operate in actinorhodin export, perhaps being sufficient for self-protection of the organism against suicide. At least four of the other five ORFs are implicated in the control of the C-6 and C-8 ring-hydroxylation reactions, lacking in actVA mutants, that occur at middle to late stages in the actinorhodin biosynthetic pathway. This conclusion was reached by genetic mapping of actVA mutants to actVA-ORF3 and-ORF5 (and perhaps -ORF4), and by the finding of strong resemblances between the protein products of actVA-ORF2 and -ORF6 and the products of genes of the oxytetracycline or tetracenomycin gene clusters that have been implicated in ring-hydroxylation reactions in the biosynthesis of these other aromatic polyketide antibiotics.     

Distribution pattern of decapod larvae off the north-western Iberian Peninsula coast (NE Atlantic)

In October 1977 the model of general circulation of the watermasses off the coast of Galicia, and the presence of a coastalupwelling, led to a high primary productivity. This high productivityin turn favoured the development of a rich population of decapodlarvae. The abundance and distribution pattern of these organismswere closely linked (i) to the abundant presence of the correspondingadult species in the area, (ii) with the spatial distributionof phytoplanktonic populations concurrently studied by Estrada[J. Plankton Res ., 6, 417–434 (1984)] and (iii) withthe hydrodynamic pattern in the area. Fifty-two decapod larvaetaxa were identified and Solenocera membranacea, Pisidia longicornis,Pilumnushirtellus and Goneplax rhomboides were the most representativespecies It was observed that the greatest concentrations oflarvae (3387 larvae 10^–2 m^–3) were to be found nearthe mouth of the Rfas Baixas (situated in the south-west ofthe coastal area) and in some zones further out to sea (863larvae 10^–2 m^–3) (due to a process of hydrodynamictransport)     

Phosphorylation of K+ channels in the squid giant axon. A mechanistic analysis

Protein phosphorylation is an important mechanism in the modulation of voltage-dependent ionic channels. In squid giant axons, the potassium delayed rectifier channel is modulated by an ATP-mediated phosphorylation mechanism, producing important changes in amplitude and kinetics of the outward current. The characteristics and biophysical basis for the phosphorylation effects have been extensively studied in this preparation using macroscopic, single-channel and gating current experiments. Phosphorylation produces a shift in the voltage dependence of all voltage-dependent parameters including open probability, slow inactivation, first latency, and gating charge transferred. The locus of the effect seems to be located in a fast 20 pS channel, with characteristics of delayed rectifier, but at least another channel is phosphorylated under our experimental conditions. These results are interpreted quantitatively with a mechanistic model that explains all the data. In this model the shift in voltage dependence is produced by electrostatic interactions between the transferred phosphate and the voltage sensor of the channel.     

gltF, a member of the gltBDF operon of Escherichia coli, is involved in nitrogen-regulated gene expression

We report here the construction and analysis of insertional mutations in each of the three genes of the gltBDF operon and the nucleotide sequence of the region downstream from gltD. Two open reading frames were identified, the first of which corresponds to gltF. The gltB and gltD genes code for the large and small subunits, respectively, of the enzyme glutamate synthase (GOGAT). gltF codes for a protein, with a molecular mass of 26,350 Da, which is required for Ntr induction. Histidase synthesis was determined as a measure of Ntr function. First, insertions in gltB, gltD or gltF all prevent Ntr induction. Second, complementation analysis indicates that high-level expression of both the gltD and gltF genes is required for the induction of the Ntr enzymes under nitrogen-limiting conditions, indicating that the phenotype of the gltB insertion probably results from polarity on gltD and gltF. Third, glutamate-dependent repression of the glt operon appears to be mediated by the product of the gltF gene. Thus, the gltBDF operon of Escherichia coli is involved in induction of the so-called Ntr enzymes in response to nitrogen deprivation, as well as in glutamate biosynthesis.