Genetic variation for rate of development in natural populations of Drosophila melanogaster

We have sampled wild chromosomes from two natural populations of Drosophila melanogaster and obtained flies fully homozygous for the second chromosome, the third chromosome, or both, as well as flies heterozygous for one or both wild chromosomes and balancer chromosomes. Rate of embryogenesis (egg laying to larval hatching) and rate of development from egg to adult are measured, by classifying the individuals into fast, intermediate, and slow developmental classes. The experiments indicate that variation for rate of embryogenesis and for rate of egg-to-adult development is plentiful in the natural populations. Various hypotheses are enunciated to account for the small range of phenotypic variation observed in wild-type individuals with respect to the two parameters (embryogenesis and egg-to-adult development) and for the difficulty in changing the mean rates by artificial selection. Appropriate experiments may decide among the hypotheses, helping us to understand the genetic control of rate of ontogenesis, which is an important fitness component.     

Comparison of blood pro/antioxidant levels before and after acute exercise in athletes and non-athletes

The aims of our study were to assess the redox state of adolescent athletes and non-athletes both at rest and after acute exposure to physical load and to find relations between parameters of redox state and morphofunctional characteristics of subjects. 58 young handball players and 37 non-athletes were subjected to body composition analysis, measuring of maximal oxygen consumption and blood sampling immediately before and after a maximal progressive exercise test. At rest, athletes had significantly higher superoxide dismutase (SOD) and catalase (CAT) activity, higher levels of glutathione (GSH) and nitric oxide (NO) and lower levels of lipid peroxidation (TBARS) compared with non-athletes. A maximal exercise test induced statistically significant rise of superoxide anion radical (O2-), hydrogen peroxide (H2O2) and NO levels in non-athletes, while TBARS levels decreased. Athletes experienced the fall in NO levels and the fall in CAT activity. After exercise, athletes had significantly lower levels of O2- compared with non-athletes. Two way repeated measures ANOVA showed that the response of O2-, NO and TBARS to the exercise test was dependent on the sports engagement (training experience) of subjects. Significant correlations between morphofunctional and redox parameters were found. These results suggest that physical fitness affects redox homeostasis.     

Regeneration of interspecific somatic hybrids between Helianthus annuus L. and Helianthus maximiliani (Schrader) via protoplast electrofusion

Helianthus maximiliani is one of the wild Helianthus species with the genes for resistance to many pathogens including Sclerotinia sclerotiorum. Unfortunately, a transfer of disease resistance genes from this species into the cultivated sunflower is limited by its poor crossability with the cultivated sunflower and sterility of interspecific hybrids. To overcome this problem, mesophyll protoplasts of Sclerotinia sclerotiorum-resistant clone of H. maximiliani were electrically fused with etiolated hypocotyl protoplasts of the cultivated sunflower inbred line PH-BC₁-91A. Fusion products were embedded in agarose droplets and subjected to different regeneration protocols. Developed microcalluses were released from the agarose and transferred into solid media. Shoot regeneration was achieved by culture of calluses on regeneration medium containing 2.2 mg l⁻¹ BAP and 0.01 mg l⁻¹ NAA after the treatment with a high concentration of 2,4 D for a limited period of time. A morphological and RAPD analysis confirmed a hybrid nature of the regenerated plants.     

Design, synthesis, and SAR studies on a series of 2-pyridinylpiperazines as potent antagonists of the melanocortin-4 receptor

A series of 2-pyridinylpiperazines derived from beta-Ala-(2,4-Cl)Phe dipeptide was synthesized for the study of their SARs and possible interactions with the MC4 receptor. Compounds such as 11k (Ki=6.5 nM) possessed high potency.     

Chromosomal inversion polymorphism of Drosophila subobscura from south‐eastern part of Europe

Five Drosophila subobscura populations from south‐eastern Europe were investigated with respect to chromosomal inversion polymorphism. They belong to central European populations and their gene arrangement frequencies are in accordance with latitudinal variation observed in this species. The new complex gene arrangement A₂₊₈₊₉, found in one of the populations analysed, may be specific for the southern Balkan refugium. A general tendency of gene arrangement frequencies to exhibit some southern characteristics was found for some of the autosomal standard arrangements.     

Purification and properties of prolylcarboxypeptidase (angiotensinase C) from human kidney.

Prolylcarboxypeptidase was purified from human kidney 1200-fold with 18% yield. The enzyme had no cathepsin A activity and appeared to be homogeneous in gel electrophoresis. The molecular weight of prolylcarboxypeptidase was estimated to be 115,000 by gel filtration. Under denaturing conditions the enzyme dissociated into subunits of 45,000 and 66,500 molecular weight. The enzyme cleaved benzyloxycarbonyl (Cbz)-Pro-Phe, representing the COOH-terminal end of angiotensin II and des-Asp1-angiotensin II (angiotensin III), at a rate of 31 micronmol/h/mg of protein. The rate of hydrolysis increased when phenylalanine in the N-protected dipeptide was replaced with alanine, valine, or leucine or when the octapeptide angiotensin II or the heptapeptide angiotensin III were the substrates. The enzyme also cleaved the angiotensin II antagonist saralasin (Sar1-Ala8-angiotensin II). The Km values were 1 mM, 2mM, and 0.77 mM with Cbz-Pro-Phe, angiotensin II, and angiotensin III, respectively. The enzyme had an acid pH optimum (4.5 to 5.5), but hydrolyzed angiotensin III at pH 7 at 50% of the optimal rate. Prolylcarboxypeptidase was inhibited by diisopropyl phosphorofluoridate and pepstatin, but not by sequestering agents or -SH reagents.     

Isolation and properties of alpha-D-mannosidase from human kidney.

Alpha-D-Mannosidase activity exists in three forms that can be separated by DEAE-cellulose chromatography, alpha-D-Mannosidase was isolated from human kidney in a homogeneous state, and was purified 2100-fold, with p-nitrophenyl alpha-D-mannoside as substrate. The purified alpha-D-mannosidase was practically free from all other glycosidases tested. The Km of the synthetic substrate with the enzyme was 1 X 10(-3) M and the pH optimum 4.5. It was inhibited by heavy metals, sodium dodecyl sulphate, urea and compounds that react with the thiol groups, and was activated by Zn2+, Na+, 2-mercaptoethanol, human albumin and gamma-globulin. The mol. wt. of the enzyme was estimated to be 180 000 +/- 4500. After pretreatment with 2-mercaptoethanol and sodium dodecyl sulphate, alpha-D-mannosidase dissociated into subunits of mol. wts. of 58 000 +/- 600 and 30 000 +/- 380 respectively. Subunits of the same molecular weights were also obtained after the enzyme was heated at 100 degrees C.     

Piperazinebenzylamines as potent and selective antagonists of the human melanocortin-4 receptor

SAR studies of a series of piperazinebenzylamines resulted in the discovery of potent antagonists of the human melanocortin-4 receptor. Compounds 11c, 11d, and 11l, which had K(i) values of 21, 14, and 15 nM, respectively, possessed low efficacy in cAMP stimulation ( approximately 15% of alpha-MSH maximal level) mediated by MC4R, and functioned as antagonists in inhibition of alpha-MSH-stimulated cAMP release in a dose-dependent manner (11l, IC(50)=36 nM).     

Genetic variability in the group of patients with congenital hip dislocation

Our study of genetic homozygosity degree includes an analysis of the presence, distribution and individual combination of 20 selected genetically controlled morpho-physiological traits in the group of patients (N = 93) with congenital hip dislocation (CDH) and in control sample consisting of school children from Belgrade (N = 200). Assuming that CDH is genetically controlled disease, we made a hypothesis that an increased homozygosity level, as well as the changed variability among the patients, could be population-genetic parameter for the prediction of the illness. Taking into consideration our experience, as well as the experience of numerous scientists who studied the nature of the inheritance of mono- and oligo-genically controlled qualitative traits, we applied a methodology to estimate the proportion of such homozygously recessive characters (HRC-TEST). This population-genetic study did not only show statistically significant difference of the middle values of genetic homozygosity (CDH-7.1+/-0.2; control - 5.2+/-0.1), but of the differences in the type of distribution too, as well as the differences in the presence of certain individual combinations of such traits. The described methodology can be used in further analyses, with hope that it can be applied as an early prognosis for decreased resistance to different diseases. The frequencies of ABO blood types in the sample of CDH patients were similar to the average value of Serbian population, while the percentage of blood group A is slightly increased. Comparing frequencies of Rh blood groups, there is no difference between tested samples.