Linkage relationships in the bovine MHC region. High recombination frequency between class II subregions

Class II genes of the bovine major histocompatibility complex (MHC) have been investigated by Southern blot analysis using human DNA probes. Previous studies revealed the presence of bovine DO , DQ , DQ , DR and DR genes, and restriction fragment length polymorphisms for each of these genes were documented. In the present study, the presence of three additional class II genes, designated DZ , DY , and DY , are reported. DZ was assumed to correspond to the human DZ gene while the other two were designated DY because their relationship to human class II genes could not be firmly established. The linkage relationships among bovine class II genes and two additional loci, TCP1B and C4, were investigated by family segregation analysis and analysis of linkage disequilibrium. The results clearly indicated that all these loci belong to the same linkage group. This linkage group is divided into two subregions separated by a fairly high recombination frequency. One region includes the C4, DQ , DQ , DR and DR loci and the other one is composed of the DO DY , DY , and TCPIB loci. No recombinant was observed within any of these subregions and there was a strong or fairly strong linkage disequilibrium between loci within groups. In contrast, as many as five recombinants among three different families were detected in the interval between these subregions giving a recombination frequency estimate of 0.17 ± 0.07. The fairly high recombination frequency observed between class 11 genes in cattle is strikingly different from the corresponding recombination estimates in man and mouse. The finding implies either a much larger molecular distance between some of the bovine class II genes or alternatively the presence of a recombinational hot spot in the bovine class II region.     

Comparison of two lignin-degrading fungi:Phlebia radiata andPhanerochaete chrysosporium

Summary The ligninolytic enzymes ofPhlebia radiata were produced in static conditions earlier developed forPhanerochaete chrysosporium. The production pattern of lignin peroxidases resembled that ofP. chrysosporium. The extracellular proteins ofPhlebia radiata were separated by isoelectric focusing. Four proteins with acidic isoelectric points (4.15) were detected by peroxidase staining. The peroxidases ofP. radiata reacted with antibodies produced against a peroxidase ofPhanerochaete chrysosporium and vice versa. Thus the lignin peroxidases of the two fungi have major similarities despite slight differences in their isoelectric points and molecular weights. Veratryl alcohol was produced by both fungi and degraded to veratraldehyde, two lactones and a quinone by the ligninolytic cultures.     

Effect of CO2 enrichment and nitrogen availability on resource acquisition and resource allocation in a grass,Bromus mollis

Summary The effects of CO₂ enrichment on the growth, biomass partitioning, photosynthetic rates, and leaf nitrogen concentration of a grass, Bromus mollis (C₃), were investigated at a favorable and a low level of nitrogen availability. Despite increases in root: shoot ratios, leaf nitrogen concentrations were decreased under CO₂ enrichment at both nitrogen levels. For the low-nitrogen treatment, this resulted in lower photosynthetic rates measured at 650 l/l for the CO₂-enriched plants, compared to photosynthetic rates measured at 350 l/l for the non-enriched plants. At higher nitrogen availability, photosynthetic rates of plants grown and measured at 650 l/l were greater than photosynthetic rates of the non-enriched plants measured at 350 l/l. Water use efficiency, however, was increased in enriched plants at both nitrogen levels. CO₂ enrichment stimulated vegetative growth at both high and low nitrogen during most of the vegetative growth phase but, at the end of the experiment, total biomass of the high and low CO₂ treatments did not differ for plants grown at low nitrogen availability. While not statistically significant, CO₂ tended to stimulate seed production at high nitrogen and to decrease it at low nitrogen.     

Immunocytochemical localization of aldolase in normal, denervated, and dystrophic chicken muscles

To investigate whether immunocytochemical localization of muscle-specific aldolase can be used for fiber phenotype determination, we produced specific antibodies against the enzyme and studied its distribution in adult chicken skeletal muscles by indirect immunofluorescence microscopy. Monoclonal antibodies against the myosin heavy chains of fast-twitch (MF-14) and slow-tonic (ALD-58) muscle fibers were also used to correlate aldolase levels with the fiber phenotype. The goat anti-aldolase antibody was found to be specific for the A form of aldolase, as evidenced by sodium dodecyl sulfate gel electrophoresis, immunotitration experiments, and immunoblot analysis. The antibody reacted strongly with the fast-twitch myofibers of normal pectoralis and posterior latissimus dorsi muscles; the phenotype of these muscle fibers was confirmed by a positive immunofluorescent reaction after incubation with MF-14 antibody. By contrast, the slow-tonic myofibers of normal anterior latissimus dorsi, which react positively with ALD-58 antibody, reacted weakly with anti-aldolase antibodies. In denervated chicken muscles, reaction to anti-aldolase antibodies was markedly reduced in fast-twitch fibers, although reaction to MF-14 was not diminished. By contrast, in dystrophic muscle, fast-twitch fibers showed reduced reactivity to anti-aldolase and marked to moderate reduction in MF-14 reactivity. Our results show that: (a) in normal muscles, reactivity to anti-aldolase matches the phenotype obtained by using anti-fast or anti-slow myosin heavy chain antibodies, and therefore can serve to identify mature fibers as fast or slow; and (b) in denervated or dystrophic muscles, the intracellular expressions of aldolase and fast-twitch myosin heavy chains are regulated independently.     

Evaluation of eight and a half years of neonatal screening for haemoglobinopathies in Birmingham

A pilot neonatal screening programme for haemoglobinopathies linked with screening for phenylketonuria and congenital hypothyroidism was reviewed. During 1978 to December 1986 137 000 neonates were tested. There were improvements in the detection rate and accuracy of diagnosis for homozygotes and mixed heterozygotes, mainly associated with the introduction of citrate agarose gel electrophoresis as a follow up procedure on all specimens showing any abnormality on the initial cellulose acetate electrophoresis.We recommend that the programme is continued on a service basis.     

Glomerular bypass shunts and distribution of glomeruli in the kidney of the lesser spotted dogfish,Scyliorhinus caniculus

Summary Scanning electron microscopy of corroded resin casts of the renal vasculature of Scyliorhinus caniculus has revealed a novel vascular pathway arising from the afferent arteriole and bypassing the glomerulus. This glomerulus bypass shunt occurred in 36% of the glomerular casts examined. The shunt ran to join a peritubular network of capillaries and thereby offers the potential to vary the degree of glomerular perfusion and control the proportion of active glomeruli. In 29% of glomeruli two efferent arterioles drained the capillary knot. Glomeruli were located close to the dorsal margin of the posterior mass of the kidney, and towards the lateral edge of the anterior lobes of the kidney of female dogfish. In male dogfish, glomeruli were evenly distributed through the posterior mass of kidney, while in female dogfish 89% of glomeruli occurred in the posterior mass and 11% of glomeruli were located within the small anterior lobes.     

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.