A rapid and specific method for the immunological identification of mycelial form cultures ofParacoccidioides brasiliensis

We developed two simple methods for extracting specific, cell-free, soluble antigens of the mold form ofParacoccidioides brasiliensis. Detection of these antigens by a microimmunodiffusion test permits the rapid and accurate identification of cultures ofP. brasiliensis. ThirtyP. brasiliensis isolates treated by these techniques produced specific exoantigens detectable by the immunodiffusion test. None of the other 78 fungal pathogens or saprophytes tested produced identical exoantigens. Personnel in any diagnostic laboratory who want a rapid and specific method for identifying or confirming suspected isolates ofP. brasiliensis can use the simple procedures described.     

Acid-catalyzed and almond β-d-glucosidase-catalyzed hydrolysis of purin-6-yl 2-deoxy-1-thio-β-d-arabino-hexopyranoside

Hydrolysis of purin-6-yl 2-deoxy-1-thio-β-d-arabino-hexopyranoside (2) to 6-mercaptopurine and 2-deoxy-d-glucose is catalyzed by hydronium ion and almond β-d-glucosidase. The dependence of rate on acidity in water and deuterium oxide indicates that 2 and its conjugate acid undergo hydrolysis via a mechanism that involves a partially rate-limiting proton transfer. Although 2 is ≈103 more reactive than 6-purinyl β-d-glucothiopyranoside (1) in dilute aqueous acid, 1 is a better substrate for almond β-d-glucosidase.     

A special class of nonlinear interactions in the visual system of the fly

Flies can detect a small object in front of a randomly contrasted background if the object undergoes small motions. The effect was investigated in fixed flying flies under open-loop conditions. The results suggest that nonlinear inhibitory interactions underly this elementary case of figure-ground discrimination.     

Quantifying the impact of ecological memory on the dynamics of interacting communities

Ecological memory refers to the influence of past events on the response of an ecosystem to exogenous or endogenous changes. Memory has been widely recognized as a key contributor to the dynamics of ecosystems and other complex systems, yet quantitative community models often ignore memory and its implications.Recent modeling studies have shown how interactions between community members can lead to the emergence of resilience and multistability under environmental perturbations. We demonstrate how memory can be introduced in such models using the framework of fractional calculus. We study how the dynamics of a well-characterized interaction model is affected by gradual increases in ecological memory under varying initial conditions, perturbations, and stochasticity.Our results highlight the implications of memory on several key aspects of community dynamics. In general, memory introduces inertia into the dynamics. This favors species coexistence under perturbation, enhances system resistance to state shifts, mitigates hysteresis, and can affect system resilience both ways depending on the time scale considered. Memory also promotes long transient dynamics, such as long-standing oscillations and delayed regime shifts, and contributes to the emergence and persistence of alternative stable states. Our study highlights the fundamental role of memory in communities, and provides quantitative tools to introduce it in ecological models and analyse its impact under varying conditions.     

Evidence for a second gene for primary microcephaly at MCPH5 on chromosome 1

Primary microcephaly has been mapped to five loci on different chromosomes. We present here the fine mapping of one of the loci, MCPH5, to a region of only 0.58 Mb located at the 1q31.3-1q32.1 junction. A genome scan was performed on five families from the Netherlands and Jordania, with 14 patients affected by microcephaly. A maximum LOD score of 4.78 was found for marker D1S1660 at the MCPH5 locus. Haplotype analysis suggests that the gene causing microcephaly is located between markers D1S3469 and D1S1660, which excludes the previously reported ASPM gene.     

Selenium content of livers from sex-linked dwarf and normal broiler breeders

Plasma concentrations of cGH, T₃, and T₄ were not different between dwarf and normal broiler breeders. Normal hens had a liver selenium content of 710±35 ng/g, and dwarf hens 656 ±nine ng/g (n=8). Following injections into a wing vein of different doses (1.5, 3, 6, 12, and 24 μg/kg) of the hypothalamic hormone TRH, GH was increased after 15 min. This effect seemed to last longer in dwarf chickens. Plasma concentrations of T₃ increased significantly 1 h after TRH in normal hens, but TRH was ineffective in raising T₃ levels in dwarf animals. The selenium content of livers obtained following decapitation after 2 h was also increased in normal hens up to 902±42 ng/g using the highest dose of TRH (24 μg/kg). This seemed not to be the case for dwarf animals. A much smaller. number of hepatic cGH receptors was also found in dwarf hens, whereas the affinity of the hepatic GH receptor was not influenced by the genotype. It is concluded that the sex-linked dwarf hens are unable to increase their hepatic T₄ into T₃ conversion following a TRH challenge probably because of a deficiency in hepatic GH receptors. The lower content of selenium in dwarfs and their inability to increase its uptake after TRH seem therefore to support the hypothesis that selenium has a direct role in the activity of the 5′-deiodinase complex.     

Same-Sex Avoidance Relations and What They Reveal about Male Competition

Avoidance relations between male kin are a pervasive social phenomenon, yet the subject has received comparatively little treatment in the anthropological literature. When anthropologists have addressed it, they have usually done so indirectly, or put forward theories better suited to explaining other social phenomena. The most common explanations one comes across in the anthropological literature to account for avoidance relationships between male kin, or what I also describe as same-sex avoidance relations in the paper, are the incest taboo and Radcliffe-Brown's theory of respect. In contrast to these explanations, I propose to demonstrate that the reason male kin avoid each other in certain types of settings is not just to maintain a sense of authority and precedence as Radcliffe-Brown's theory implies, or to avoid contravening incest prohibitions, which as Robert Lowie pointed out long ago is incorrect. Rather, because closely related male kin should not compete with each other, as this would contravene the ideology of descent which demands loyalty to one's kin.     

Oviposition of the Colorado potato beetle (Leptinotarsa decemlineata) and natural predation on its egg masses in Bt-expressing fields

Generalist predators are relevant natural enemies of the Colorado potato beetle (CPB) in Europe. In fields of insect resistant genetically modified plants (GMPs), predators could be exposed to toxins either directly (e.g., via pollen), or indirectly through feeding on herbivorous prey. Hence, they represent an important functional group to consider when studying environmental impacts of GMPs. CPB females show a ‘bet-hedging’ strategy in spatial and temporal distribution of eggs, through which the species tries to minimize the risks of progeny loss due to adverse conditions. Experimental fields of GM eggplants expressing Cry3Bb toxin and potatoes expressing Cry1Ab toxin were set up. CPB egg masses were counted on naturally infested plants at four time points during the field season of each crop. To assess predation, newly deposited egg masses were marked at the same dates. Daily visual observations were conducted recording the numbers of intact or preyed eggs and neonate larvae. In both cases, oviposition was similar between GM and control plots, as the number of egg masses per plant and the number of eggs per mass did not differ significantly between treatments. A statistical analysis of the spatial distribution of egg masses revealed a similar aggregation in the potato field, whereas in the eggplant field, the variance of the number of egg masses per plant was smaller than expected in GMP plots. The predation rate was similar between treatments. These results suggest that the ecological function of natural predation on CPB eggs in GM plots was not impaired.     

A Deletion in the α2B‐Adrenergic Receptor Gene and Autonomic Nervous Function in Central Obesity

Objective: We investigated the impact of a three‐amino acid deletion (12Glu9) polymorphism in the α_2B‐adrenergic receptor gene on autonomic nervous function. The short form (Glu⁹/Glu⁹) of the polymorphism has previously been associated with a reduced basal metabolic rate in obese subjects. Because autonomic nervous function participates in the regulation of energy metabolism, there could be a link between this polymorphism and autonomic nervous function. Research Methods and Procedures: Data of a 10‐year follow‐up study with 126 nondiabetic control subjects and 84 type 2 diabetic patients were used to determine the effects of the 12Glu9 polymorphism on autonomic nervous function. A deep breathing test and an orthostatic test were used to investigate parasympathetic and sympathetic autonomic nervous function. In addition, cardiovascular autonomic function was studied using power spectral analysis of heart rate variability. Results: No significant differences were found in the frequency of the 12Glu9 deletion polymorphism between nondiabetic and diabetic subjects. The nondiabetic men with the Glu⁹/Glu⁹ genotype, especially those with abdominal obesity, had significantly lower total and low‐frequency power values in the power spectral analysis when compared with other men. Furthermore, in a longitudinal analysis of 10 years, the decrease in parasympathetic function was greater in nondiabetic men with the Glu⁹/Glu⁹ genotype than in the men with the Glu⁹/Glu¹² or Glu¹²/Glu¹² genotypes. Discussion: The results of the present study suggest that the 12Glu9 polymorphism of the α_2B‐adrenergic receptor gene modulates autonomic nervous function in Finnish nondiabetic men. In the nondiabetic men with the Glu⁹/Glu⁹ genotype, the general autonomic tone is depressed, and vagal activity especially becomes impaired with time. Furthermore, this association is accentuated by central obesity.