Genetics of the Nematode Heterorhabditis bacteriophora Strain HP88: The Diversity of Beneficial Traits

Genotypic variation among infective juveniles of Heterorhabditis bacteriophora (strain HP88) in heat, desiccation, ultraviolet tolerance, and host-finding ability was assessed by comparing the performance of inbred lines of this entomopathogenic nematode in laboratory assays. Each line consisted of highly homozygous offspring originating from one individual obtained from a natural population. Considerable variation in all four traits was detected among the different inbred lines. The heritability values for heat or ultraviolet tolerance and for host-finding ability were high, indicating that selection should be an efficient way for improving these traits in the population. The results for desiccation tolerance varied considerably within each line. Heritability value was low, indicating that the results were influenced mainly by environmental variation and suggesting that selective breeding for higher desiccation tolerance would be inefficient. Improvement through induction of mutations may be a better alternative in this population.     

Neural organization of the locomotive oscillator

We study the relation of neural development, organization, and activity to behavior. We provide a model of the locomotive oscillator, a neural system supplying alternating stimulation to extensor and flexor muscles creating an oscillatory motion. We propose a protocol by which this neural system starting from unstructured, unconnected neural populations develops structure and function. The protocol is studied by both computer simulation and mathematical analysis. Our main results are 1 The locomotive oscillator self-organizes and maintains its organization, assuming certain properties of the neural populations. 2 Imperfections disturbing the functional adequacy of the neural populations may lead to the deterioration and disappearance of the oscillatory behavior. 3 The locomotive oscillator may fail to organize if the development is not staged in time.     

Origin of the proximal coronary artery stems and a review of ventricular vascularization in the chick embryo

The objective of this study was to determine how the coronary artery stems develop in the chick embryo. The hearts of 51 ink-injected and cleared chick embryos, aged embryonic days 6, 6.5, 7, 7.5, 9, and 10, were dissected, examined, and selectively photographed. Two representative hearts from each group were paraffin embedded, serially sectioned at 10 microns, and examined for aortic endothelial budding. We found that the proximal coronary artery did not appear to grow outward from the aorta as commonly described in the literature. It appeared to originate from a capillary ring which encircled the aortic and pulmonary outflow tracts. On embryonic day 7.5, one to three channels arising from this ring penetrated each aortic sinus, in an area of darker textured endothelium. Histologically and grossly, multiple channels were still apparent on day 9, particularly in the left coronary artery. One of these channels always became dominant to form the stem. Each stem, which varied in length from embryo to embryo, always ended in a plexus of sinusoidal endothelial tubes. By day 10, the coronary artery stems were longer, with many major branches. Histologically, evidence of multiple channels still was visible. It is significant that channels from the bulbar vascular ring penetrated the aorta at very specific points in the aortic sinuses and did not penetrate the pulmonary trunk or other aortic sites. We believe this fact indicates that the penetration of the aortic sinuses by channels from the bulbar vascular ring represents a controlled invasion of the aorta.     

Phylogenetic signal and variation of visceral pigmentation in eight anuran families

Provete, D. B, Franco‐Belussi, L., de Souza Santos, L. R., Zieri, R., Moresco, R. M., Martins, I. A., de Almeida, S. C., & de Oliveira, C. (2012). Phylogenetic signal and variation of visceral pigmentation in eight anuran families. —Zoologica Scripta, 41, 547‐556. Visceral pigmentation is found in several organs and structures of ectothermic animals, comprising the extracutaneous pigmentary system. Its function is not well defined, although it is known that melanin is produced and stored inside pigmented cells. Previous studies demonstrated that the distribution of visceral pigmentation is neither homogeneous among organs among anuran species. We described the diversity of visceral pigmentation in 12 organs/structures from 32 anuran species belonging to eight families in a phylogenetic context. We also determined in which node(s) of the phylogeny there is more variation in the pigmentation and whether this variation has phylogenetic signal. The visceral pigment cells in organs and structures of the abdominal cavity varied among genera. All species had pigmentation in the urogenital and cardiorespiratory systems, whereas the stomach lacks pigmentation in all species. We also found a phylogenetic signal for pigmentation in all organs and structures taken together, besides heart, testes, lumbar parietal peritoneum and lumbar nerve plexus when considered separately. Overall, considering all organs, the highest diversity of categories of pigmentation was found in the nodes corresponding to Cruciabatrachia and Athesphatanura. This study constitutes the first step towards understanding the evolution of visceral pigmentation in anurans.     

Adenylate kinase deficiency and malignant hyperthermia

Summary In a report of two patients who died of malignant hyperthermia, muscle adenylate kinase deficiency was identified in the father and brother of the deceased. To determine if this enzyme deficiency was a biochemical marker for susceptibility to malignant hyperthermia, we measured adenylate kinase in muscle of three survivors of malignant hyperthermia (MH) and five relatives of survivors of MH attacks with positive caffeine contracture tests. Neither the activity nor the electrophoretic mobility of adenylate kinase differed from four control values. The results show that muscle adenylate kinase deficiency is not a biochemical abnormality shared by all individuals susceptible to malignant hyperthermia.This work has been supported by grants from Muscular Dystrophy Association of America, NIH (NS 11766)Dr. Cerri is recipient of a postdoctoral fellowship from Muscular Dystrophy association and Dr. Willner is recipient of a Teacher Investigator Award from NINCDS     

Phenotypic and Genetic Analysis of a Mutant of Heterorhabditis bacteriophora Strain HP88

Induction and characterization of a morphological mutant are described for Heterorhabditis bacteriophora strain HP88. A homozygous inbred line was used as the base population for mutagenesis and genetic analysis of mutations. Mutagenesis was induced by exposing young hermaphrodites to 0.05 M ethyl methanesulfonate. A dumpy mutant (designated Hdpy-l) was isolated from the F₂ generation of the mutagenized population. Morphological studies with light and scanning electron microscopy revealed that the head region of the adult stage was compressed. The head region of the infective juvenile was distorted and the mouth open. Backcross with the original population was successful only between mutant hermaphrodites and wild type males; 50-100 percent of the progeny of this cross maintained the dumpy phenotype, indicating that the ratio between self- and external fertilization of the eggs is > 1 and that the dumpy mutation is recessive.