Gamete production, sex hormone secretion, and mating behavior uncoupled

A common observation for seasonally breeding vertebrates is that the reproductive processes of gamete production, sex steroid hormone secretion, and mating behavior coincide, and further, that sex steroid hormones activate mating behavior. The postulate of hormone-dependence of mating behavior is based primarily on detailed studies of laboratory and domesticated species. However, comparison of a wide array of vertebrates reveals numerous exceptions to this supposed rule. Consideration of these species indicates that there is no fixed or intrinsic causal association among gamete production, sex hormone secretion, and mating behavior within any of the classes of vertebrates.     

Oxidative degradation of thymine with O2 promoted by L-ascorbic acid and Cu(II) ion

Oxidation of thymine with O2 was promoted by copper(I) ion generated from reaction of L-ascorbic acid (AA) with copper (II) ion. The main oxidation products were thymine glycol (TG) and N-formyl-N'-pyruvylurea (FPU). At higher concentration of O2, formation of FPU was favored, while TG was dominant at higher Cu(II) ion and lower O2 concentrations. Reaction mechanism involving hydroxy thyminyl radical was proposed.     

Detection of genetic variants affecting cattle behaviour and their impact on milk production: a genome‐wide association study

Behaviour traits of cattle have been reported to affect important production traits, such as meat quality and milk performance as well as reproduction and health. Genetic predisposition is, together with environmental stimuli, undoubtedly involved in the development of behaviour phenotypes. Underlying molecular mechanisms affecting behaviour in general and behaviour and productions traits in particular still have to be studied in detail. Therefore, we performed a genome‐wide association study in an F₂ Charolais × German Holstein cross‐breed population to identify genetic variants that affect behaviour‐related traits assessed in an open‐field and novel‐object test and analysed their putative impact on milk performance. Of 37 201 tested single nucleotide polymorphism (SNPs), four showed a genome‐wide and 37 a chromosome‐wide significant association with behaviour traits assessed in both tests. Nine of the SNPs that were associated with behaviour traits likewise showed a nominal significant association with milk performance traits. On chromosomes 14 and 29, six SNPs were identified to be associated with exploratory behaviour and inactivity during the novel‐object test as well as with milk yield traits. Least squares means for behaviour and milk performance traits for these SNPs revealed that genotypes associated with higher inactivity and less exploratory behaviour promote higher milk yields. Whether these results are due to molecular mechanisms simultaneously affecting behaviour and milk performance or due to a behaviour predisposition, which causes indirect effects on milk performance by influencing individual reactivity, needs further investigation.     

Field Measurements Indicate Unexpected,Serious Underestimation of Mussel Heart Rates and Thermal Tolerance by Laboratory Studies

Attempts to predict the response of species to long-term environmental change are generally based on extrapolations from laboratory experiments that inevitably simplify the complex interacting effects that occur in the field. We recorded heart rates of two genetic lineages of the brown mussel Perna perna over a full tidal cycle in-situ at two different sites in order to evaluate the cardiac responses of the two genetic lineages present on the South African coast to temperature and the immersion/emersion cycle. “Robomussel” temperature loggers were used to monitor thermal conditions at the two sites over one year. Comparison with live animals showed that robomussels provided a good estimate of mussel body temperatures. A significant difference in estimated body temperatures was observed between the sites and the results showed that, under natural conditions, temperatures regularly approach or exceed the thermal limits of P. perna identified in the laboratory. The two P. perna lineages showed similar tidal and diel patterns of heart rate, with higher cardiac activity during daytime immersion and minimal values during daytime emersion. Comparison of the heart rates measured in the field with data previously measured in the laboratory indicates that laboratory results seriously underestimate heart rate activity, by as much as 75%, especially during immersion. Unexpectedly, field estimates of body temperatures indicated an ability to tolerate temperatures considered lethal on the basis of laboratory measurements. This suggests that the interaction of abiotic conditions in the field does not necessarily raise vulnerability to high temperatures.     

Pleiotropic mutations in Serratia marcescens which increase the synthesis of certain exocellular proteins and the rate of spontaneous prophage induction

Summary Mutants of S. marcescens HY have been isolated which produce between five and one hundred times more exocellular nuclease than does the parental strain. These nuclease-superactive (nuc ^su) mutants are highly pleiotropic: they produce more exocellular marcescin A and lipase than the wild-type and their ability to inactivate penicillin G is increased. Furthermore, all nuclease-superactive mutants if lysogenic for the heteroimmune phages Kappa and/or y show spontaneous induction rates for both prophages 10 to 200 fold greater than the corresponding wild-type. Nuc ^su mutants of independent origin synthesize nuclease and marcescin A in approximately proportional amounts although the corresponding structural genes do not seem to be part of a single operon because some bacteriocin-superactive mutants were isolated which showed an increase of the synthesis of marcescin A only. Nuclease-defective (nuc) mutants are all of the non-pleiotropic type. Three hypotheses to explain the effects of the nuc ^su mutation at the molecular level are discussed and some evidence in support of one of these hypotheses (gene-dosage effect) is presented in an accompanying paper (Timmis and Winkler, 1973).     

Biochemical and cytogenetic studies on the Nucleolus Organizing Regions (NOR) of Man

Summary The hybridization kinetics of DNA with labeled (18s+28s)rRNA from HeLa cells was determined in patients with trisomy 21, healthy probands with normal karyotype and in carriers of a t(DqGq) centric fusion. The results are in, accordance with the saturation values obtained earlier for these probands:Three patients with trisomy 21 showed an increased saturation level. In 2 of these patients the excess of rDNA exceeded the expected value considerably.Three of the investigated translocation carriers t(14q21q) showed significantly reduced saturation values, while results of a fourth proband with a dicentric chromosome t(15q21q) were found to be within the range of normal probands.The heterogeneous results were correlated with the cytogenetic characteristics of the acrocentric chromosomes. It is expected that these differences could be explained on the basis of family analysis.

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Zusammenfassung Hybridisierungskinetiken der DNA mit markierter (18s+28s)rRNA aus HeLa-Zellen wurden ermittelt bei Patienten mit Trisomie 21, gesunden Probanden mit normalem Karyotyp und Trägern einer zentrischen Fusion t(DqGq). Die Ergebnisse bestätigen die bereits früher ermittelten Sättigungswerte von Hybridisierungen bei diesen Probanden:3 Patienten mit Trisomie 21 zeigten erhöhte Sättigungsniveaus. Bei 2 dieser Patienten übersteigt der Überschuß an rDNA den Erwartungswert erheblich.3 der untersuchten Translokationsträger t(14q21q) hatten signifikant erniedrigte Sättigungswerte, während die vierte Probandin mit dem dizentrischen Chromosom t(15q21q) im Normbereich lag.Die unterschiedlichen Befunde werden mit den cytogenetischen Eigenschaften der akrozentrischen Chromosomen in Zusammenhang gebracht. Es wird erwartet, daß diese Unterschiede sich durch Familienuntersuchungen aufklären lassen.

     

Effects of 1-ethynylpyrene and related inhibitors of P450 isozymes upon benzo[a]pyrene metabolism by liver microsomes

The effects of three aryl acetylenes, 1-ethynylpyrene (EP), 2-ethynylnaphthalene (EN) and 3-ethynylperylene (EPE), upon the metabolism of benzo[a]pyrene (BaP) by microsomes isolated from rat liver were investigated. These aryl acetylenes all inhibited the total metabolism of BaP. Formation of BaP 7,8-dihydrodiol and BaP tetrol products by microsomal preparations from rats that had been pretreated with 3-methylcholanthrene (3MC) were preferentially inhibited. The effects of EP upon the metabolism of BaP 7,8-dihydrodiol by microsomes from rat liver were also studied. This aryl acetylene strongly inhibited the formation of BaP tetrols from BaP 7,8-dihydrodiol by liver microsomes both from untreated rats and from rats pretreated with 3MC, but enhanced the conversion of the BaP dihydrodiol into other metabolites.