Linkage analyses of multiple endocrine neoplasia, type 2 (MEN-2) with 23 classical genetic polymorphisms

Linkage analyses were performed in a single large family with multiple endocrine neoplasia, type 2 (MEN-2) between 23 classical genetic polymorphisms and MEN-2. We exclude close linkage of the locus for MEN-2 with ABO, ACP1, BF, ESD, Fy, GALT, GLO1, Jk, MNSs, P, PGM1, Rh and TF, as well as absolute linkage with GPT. These results raise to about 6% the proportion of the genome that has been excluded in this one family. Somewhat positive lod scores were obtained for GC (0.92 at theta = 0), GPT (0.73 at theta = 0.1) and HP (1.49 at theta = 0.05); although not statistically significant, these findings suggest regions of the genome that warrant additional study.     

Nucleotide sequence analysis of the lemur beta-globin gene family: evidence for major rate fluctuations in globin polypeptide evolution

Lemur beta-related globin genes have been isolated and sequenced. Orthology of prosimian and human epsilon-, gamma-, and beta-related globin genes was established by dot-matrix analysis. All of these lemur globin genes potentially encode functional beta-related globin polypeptides, though precisely when the gamma-globin gene is expressed remains unknown. The organization of the 18-kb brown lemur beta-globin gene cluster (5' epsilon-gamma-[psi eta-delta]-beta 3') is consistent with its evolution by contraction via unequal crossing-over from the putative ancestral mammalian beta-globin gene cluster (5' epsilon-gamma- eta-delta-beta 3'). The dwarf lemur nonadult globin genes are arranged as in the brown lemur. Similar levels of synonymous (silent) nucleotide substitutions and noncoding DNA sequence differences have accumulated between species in all of these genes, suggesting a uniform rate of noncoding DNA divergence throughout primate beta-globin gene clusters. These differences are comparable with those observed in the nonfunctional psi eta pseudogene and have therefore accumulated at the presumably maximal neutral rate. In contrast, nonsynonymous (replacement) nucleotide substitutions show a significant heterogeneity in distribution for both the same gene in different lineages and different genes in the same lineage. These major fluctuations in replacement but not silent substitution rates cannot be attributed to changes in mutation rate, suggesting that changes in the rate of globin polypeptide evolution in primates is not governed solely by variable mutation rates.      

The physiological basis of seed dormancy in Avena fatua. II. On the involvement of alternative respiration in the stimulation of germination by sodium azide

Chromatography on DEAE-cellulose of an extract from etiolated leaves of sorghum ( Sorghum vulgare Pers. cv. INRA 450), a C₄ plant, gave only one form of phosphoenol pyruvate carboxylase with functional and regulatory properties of a C₃ type plant enzyme. Greening of the leaves resulted in a significant increase in activity. This increase was due to the appearance of a new form of the enzyme, which eluted at lower ionic strength and exhibited new properties. This form was glucose-6-P activated and showed a sigmoidal curve response to the concentration of the substrate phosphoerralpyruvate. These kinetic properties are typical of a C₄ plant enzyme.     

THE FINE STRUCTURE OF ASTROCYTES IN THE CEREBRAL CORTEX AND THEIR RESPONSE TO FOCAL INJURY PRODUCED BY HEAVY IONIZING PARTICLES

Normal and reactive astrocytes in the cerebral cortex of the rat have been studied with the electron microscope following focal alpha particle irradiation. The presence of glycogen and approximately 60-A fibrils identify astrocyte cytoplasm in formalin-perfused tissue. The glycogen particles facilitate the identification of small processes and subpial and perivascular end-feet. Both protoplasmic and fibrous astrocytes contain cytoplasmic fibrils and should be distinguished on the basis of the configuration of their processes and their distribution. Acutely reactive astrocytes are characterized by a marked increase in the number of glycogen granules and mitochondria from the first day after irradiation. These cells later hypertrophy and accumulate lipid bodies and increased numbers of cytoplasmic fibrils. The glial "scar" consists of a greatly expanded volume of astrocyte cytoplasm filled with fibrils and displays no signs of astrocyte death, reversion to primitive forms, or extensive multiplication.     

Enzyme polymorphism in Schistosoma mattheei from cattle in the Eastern Transvaal Lowveld

Enzyme electrophoresis was conducted on 10 Schistosoma mattheei adult worm samples, comprising 270 individuals, collected from cattle in the Eastern Transvaal Lowveld. Glucose-6-phosphate dehydrogenase (G6PDH) was studied in all the samples and phosphoglucomutase (PGM) and malate dehydrogenase (MDH) in five populations each. Only one population was polymorphic for G6PDH. In this population, in addition to the allele found in all the other samples, a second allele occurred with a similar Rf value to S. haematobium. The two alleles were in Hardy-Weinberg equilibrium. MDH-1 exhibited two alleles. However, these alleles were not in equilibrium. In certain populations, heterozygotes occurred together with homozygotes of one of the alleles only. PGM was monomorphic in all the populations studied.     

The link between vascular deterioration and branched chain amino acids in a population with high glycated haemoglobin: the SABPA study

Globally the prevalence of non-communicable diseases, such as hypertension and type 2 diabetes, are escalating. Metabolomic studies indicated that circulating branched chain amino acids (BCAAs) are associated with insulin resistance, coronary artery disease and increased risk for cardiovascular events. We aimed to extend the current understanding of the cardiovascular risk associated with BCAAs. We explored whether BCAAs are related to markers of cardiovascular disease in a bi-ethnic population and whether this relationship was influenced by chronic hyperglycaemia. We included 200 African and 209 Caucasian participants, and determined their ambulatory blood pressure and carotid intima-media thickness (cIMT). We analysed blood samples for glycated haemoglobin (HbA1c) and BCAAs. Participants were stratified into two groups according to their HbA1c value using the median cut-off value of 5.6 %. Ambulatory BP, cIMT and BCAAs were significantly higher (all p < 0.001) in the high HbA1c group. Single regression analyses indicated significant positive associations of ambulatory blood pressure and cIMT with BCAAs (all p < 0.05) in both the groups. These associations between ambulatory systolic blood pressure (SBP) (r = 0.16, p = 0.035) and cIMT (r = 0.22, p = 0.004) with BCAAs remained in the high HbA1c group after adjusting for age, gender, ethnicity and body mass index (BMI) and were confirmed in multiple regression analyses (ambulatory SBP: R ² = 0.17, β = 0.21, p = 0.005 and cIMT: R ² = 0.30, β = 0.19, p = 0.003). Our results demonstrate that BCAAs are independently related to ambulatory BP and cIMT in individuals with high HbA1c levels and suggest that potential cardiovascular deterioration accompany the rise in BCAAs in conditions of hyperglycaemia.     

Morphology of the elygium and developing umbraculum in the eye of Amietia vertebralis tadpoles

The elygium is a darkly pigmented projection over the pupil of the tadpoles of certain species that live mostly at high altitudes. It has been suggested that this structure shades the retina, protecting it from high UV levels. In post‐metamorphic individuals, the elygium is replaced by a structure known as an umbraculum. Confusion arose in the past from the inconsistent use of terminology when referring to these two structures. While they may serve the same function, these structures differ fundamentally in structure and origin. Our investigation of the ultrastructure of the eye in Amietia vertebralis tadpoles, using electron and light microscopy, revealed that the elygium consists of an accumulation of melanophores situated within the inner cornea, whereas the umbraculum is a dorsal extension of the iris pigment epithelium, analogous to the ventral pupillary nodule, which is present in most frog species. In A. vertebralis, the umbraculum starts to develop on the iris of older tadpoles (Gosner [ 1960 ] stage 37 Herpetologica 16:183–190), medial to the overlying elygium. A smaller, ventral elygium is also present in this species and is similar in structure to the dorsal elygium. The development of the elygium over a six‐month period is also described. J. Morphol., 2013. © 2013 Wiley Periodicals, Inc.     

DDT RESIDUES AND MERCURY LEVELS IN REED CORMORANTS ON LAKE KARIBA: A HAZARD ASSESSMENT

Summary

Douthwaite, R.J., Hustler, C.W., Kruger, J. &; Renzoni, A. 1992. DDT residues and mercury levels in Reed Cormorants on Lake Kariba: a hazard assessment. Ostrich 63: 123–127.

Samples of liver and visceral fat from 86 cormorants Phalacrocorax africanus collected at the eastern end of Lake Kariba between January and October 1986 were analysed for 22 organochlorine compounds. Residues of four insecticides were detected but concentrations of hexachlorobenzene, Hch and lindane in liver did not exceed 0.3 mg kg^?1 extractable lipid. Unaltered DDT, or its metabolites DDD and DDE, were found in every sample, almost all as DDE. Levels varied seasonally, with the highest found between May and September. Risk of increased mortality in full-grown birds was negligible but visceral fat of adult females contained DDE levels associated elsewhere with eggshell thinning and breeding failure in a related species. In a separate study, tissues from ten birds were analysed for mercury. Up to 13.6 mg mercury kg¹ dry weight was found in liver tissue but this should not increase risk of mortality significantly.