Guanine nucleotide regulatory protein alterations in young Milan hypertensive strain rats

Vascular smooth muscle cell membranes from prehypertensive rats of the Milan hypertensive strain (MHS) were used to examine adenylyl cyclase activity and its regulation by guanine nucleotide regulatory proteins (G-proteins). Basal adenylyl cyclase activity was similar in MHS and Milan normontensive strain (MNS) membranes. Forsokolin (10^?4 M) produced a significantly greater stimulatory response in MHS membranes, but this was not observed with NaF (10^?2 M). Isoporterenol (10^?4 M) caused a significantly decreased stimulation of adenylyl cyclase activity in MHS membranes, while prostaglandin E₁ (10^?5 M) produced similar responses in the two strains. G_i function and GTP responses, as observed by biphasic effects of GTP on isoproterenol-stimulated membranes, were similar in both strains. The levels of G_i2α and G_qα/G₁₁α were similar in the two strains, while the levels of G_sα (44 and 42 kDa forms) and the β-subunit were significantly reduced by ～20% in MHS membranes. The α-subunit of G_i3 was dramatically reduced by ～80% in MHS membranes. The affinities of β-adrenergic receptors for the antagonist, cyanophindolol, were similar in the two strains; however, the number of β-adrenoceptors was substantially reduced in MHS membranes. These findings may be of relevance to altered vascular reactivity and transmembrane ion distribution observed in the MHS.     

On the nature of the energised state of submitochondrial particles; Investigations with N-aryl naphthalene sulphonate probes

1. A further investigation has been made of the way in which the fluorescent probes 1-anilino-naphthalene-8-sulphonate and 2-(N-methyl-anilino)naphthalene-6-sulphonate report on the energised state of bovine heart submitochondrial particles.2. A comparison of the probe responses to energisation with ATP or to a potassium diffusion potential has been made. The fluorescence enhancements seen in these two cases have different characteristics, and in view of this it is questioned whether a substrate generated energised state of a submitochondrial particle can be equated with a trans-membrane potassium diffusion potential.3. Substitution of ITP for ATP reduces the rate at which either of the probes respond to energisation. In contrast reducing the ATPase activity of the particles by treatment with the covalent ATPase inhibitors 4-chloro-7-nitrobenzofurazan or N,N′-dicyclohexyl-carbodiimide has no effect on this rate. This finding that the rate of the fluorescence changes is directly sensitive to events at the level of the ATPase, but not to the total ATPase activity, suggests that this rate may not be controlled by a delocalised energised state. Reduction of ATPase activity decreases the extent of the fluorescence enhancement and a relationship between the change in probe fluorescence and ATPase activity is given.4. The results in this paper are discussed in the context of the mechanisms which have been proposed to account for the fluorescence enhancements of N-aryl naphthalene sulphonate probes upon energisation of submitochondrial particles.     

Blood groups and types,hemoglobin variants,and G-6-PD deficiency among Abu Dhabians in the United Arab Emirates

Some erythrocyte genetic factors were studied in the indigenous population of Abu Dhabi, the capital of the United Arab Emirates, on the south-eastern coast of the Arabian peninsula. Determinations carried out included blood groups and types ABO, MNS, Rh_o, KkJs^a, Fy^aFy^b, P₁, Le^a, Vel^a, hemoglobin variants, and screening for G-6-PD deficiency. Prevalence of most blood groups and types harmonized with that among neighboring Arabs and some Arabs elsewhere. The MS and NS gene complexes were noticeably high. African admixture was expressed by the presence of Js^a and Hb S and large numbers of Fy. G-6-PD deficiency was rather high.     

Endoplasmic reticulum-associated degradation (ERAD) and free oligosaccharide generation in Saccharomyces cerevisiae

In Saccharomyces cerevisiae, proteins with misfolded lumenal, membrane, and cytoplasmic domains are cleared from the endoplasmic reticulum (ER) by ER-associated degradation (ERAD)-L, -M, and -C, respectively. ERAD-L is N-glycan-dependent and is characterized by ER mannosidase (Mns1p) and ER mannosidase-like protein (Mnl1p), which generate Man(7)GlcNAc(2) (d1) N-glycans with non-reducing α1,6-mannosyl residues. Glycoproteins bearing this motif bind Yos9p and are dislocated into the cytoplasm and then deglycosylated by peptide N-glycanase (Png1p) to yield free oligosaccharides (fOS). Here, we examined yeast fOS metabolism as a function of cell growth in order to obtain quantitative and mechanistic insights into ERAD. We demonstrate that both Png1p-dependent generation of Man(7-10)GlcNAc(2) fOS and vacuolar α-mannosidase (Ams1p)-dependent fOS demannosylation to yield Man(1)GlcNAc(2) are strikingly up-regulated during post-diauxic growth which occurs when the culture medium is depleted of glucose. Gene deletions in the ams1Δ background revealed that, as anticipated, Mns1p and Mnl1p are required for efficient generation of the Man(7)GlcNAc(2) (d1) fOS, but for the first time, we demonstrate that small amounts of this fOS are generated in an Mnl1p-independent, Mns1p-dependent pathway and that a Man(8)GlcNAc(2) fOS that is known to bind Yos9p is generated in an Mnl1p-dependent, Mns1p-independent manner. This latter observation adds mechanistic insight into a recently described Mnl1p-dependent, Mns1p-independent ERAD pathway. Finally, we show that 50% of fOS generation is independent of ERAD-L, and because our data indicate that ERAD-M and ERAD-C contribute little to fOS levels, other important processes underlie fOS generation in S. cerevisiae.     

Relationships among alterations in renal membrane sodium transport,renin and aminopeptidase M activities in genetic hypertension

Rats of the Milan Hypertensive Strain (MHS) may be considered a useful model for understanding the genetic molecular mechanism underlying a primary form of hypertension in at least a subgroup of patients. Many differences between MHS and its normotensive control strain (MNS) were found at the organ, cellular and biochemical level. In the present investigation renal cell membrane proteins (BBMV) were analysed by two-dimensional electrophoresis and a difference between MHS and MNS was shown in a polypeptide of 32 kDa, subsequently identified as the C-terminal fragment of aminopeptidase M (APM). The activity of the enzyme was higher in MHS. Genetic relationships between this enzyme and the other biochemical cellular abnormalities of MHS, namely sodium transport in BBMV and renin activity in kidney cortex were investigated in MHS, MNS and in two inbred recombinant strains. This analysis showed that faster sodium transport, low kidney levels of renin and hypertension, but not differences in two-dimensional electrophoretic pattern and in aminopeptidase M activity, cosegregated in recombinant strains. These results are consistent with the hypothesis that the faster sodium transport can be considered a primary cellular abnormality responsible for hypertension in MHS and that the aminopeptidase difference is not involved in the cellular abnormalities.     

A survey of phenotype distribution of subgroup A2, blood groups MNS, P, and Kell in the Kazak nationality living in northern Xinjiang of China

The research was undertaken to study the phenotypic polymorphisms of the subgroup A2, blood groups MNS, P, and Kell in the Kazakh population in northern Xinjiang, China and establish data on rare blood group antigens in the Kazakh population, in order to provide references for clinical blood transfusion safety and prevention of hemolytic disease of the new born. In this study, 6,862 unrelated Kazakh individuals in northern Xinjiang were randomly selected, and their blood samples were collected for serological testing. The antigens of A, B, A1, M, N, P1 and K were detected by serological saline tube method, and the antigens of S, s, and k were detected by the microcolumn gel antiglobulin card method. The results were as follows: ① The detection rates of subgroup A2 in group A and group AB were 7.08% and 21.79%, respectively; ② The allele frequencies of the blood groups MNS, P and Kell were M=0.5668, N=0.4332, S=0.1860, s= 0.8140, P1=0.2848, P2=0.7152, K1=0.0096, K2=0.9904. The observed values and expected values of frequency distribution of genotypes were compared by χ² test, which conformed to the Hardy-Weinberg genetic law (P>0.05); ③ Fourteen cases of S^-s^- rare phenotype were detected in MNS blood group system, with a frequency of 1.16%; ④ The frequency of K antigen in the Kell blood group system was 1.92%. One case of rare KK homozygote was detected, with a frequency of 0.034%. Our study suggested that the distribution of gene frequency of subgroup A2, blood groups MNS, P and Kell in the Kazakh population in northern Xinjiang has its own characteristics, and their blood group MNS has unique genotypes. The positive rate of K antigen of blood group Kell in the Kazakh population was significantly higher than Chinese Han population.