Slug reproductive maturation hormone: In vivo evidence for long-day stimulation of secretion from brains and cerebral ganglia

Summary Slugs (Limax maximus) that would normally remain reproductively immature in short-day light cycles (LD 816) were employed as hosts for brain explants. Reproductive tract development was induced in hosts receiving whole brains from donors exposed to long days (LD 168), but no development occurred in hosts receiving short-day brains (Fig. 1 and Table 1). Development equivalent to that induced by whole, long-day brains was also induced by implanting only cerebral ganglia from long-day donors (Table 2). Implantation of subesophageal complexes from long-day donors failed to stimulate reproductive organ growth but significantly inhibited somatic growth (Table 2). The results indicate that long-day photoperiods stimulate the release of a maturation-inducing factor from cells located in the cerebral ganglia of theLimax brain. It also appears that a growth-inhibiting factor is produced by the subesophageal ganglia.Abbreviations ASO accessory sex organs - MH Maturation hormone This work was supported in part by a grant from NIH (AI 16259) to Dr. Sokolove.     

Inhibition of Gene Transfer by Antiserum and Identification of Serotypes of Sex Pili

Gene transfer by conjugation due to F or R (drug resistance) factors is inhibited by antibody to the sex pili. Serological analysis is able to distinguish between the sex pili determined by closely related sex factors, and the specificity of inhibition of transfer agrees with that previously determined by direct electron microscopical observation of antibody bound to the sex pili (10). Inhibition of transfer can therefore be applied to the identification of wild-type R factors with repressed sex factors that determine too few pili to be examined directly. It can also be used to differentiate the activities of two unrelated sex factors in the same donor bacterium.     

Topiramate modulation of kainate-induced calcium currents is inversely related to channel phosphorylation level

Topiramate (TPM) is a structurally novel broad-spectrum anticonvulsant known to modulate the activity of several ligand- and voltage-gated ion channels in neurons. These include an inhibitory effect on the AMPA and kainate subtypes of glutamate receptors, mixed modulatory effects (usually positive) on some types of GABAA receptors, negative modulatory effects on some types of voltage-gated Na+ and Ca2+ channels, and a positive modulatory effect on at least one type of K+ channel. The nature of these effects at the molecular level has not been established, but two previous studies have implicated the phosphorylation state of these receptor/channel complexes as an influencing factor in the activity of TPM. Here, we report that the ability of TPM to inhibit a kainate-induced accumulation of free Ca2+ in cultured neurons from rat cerebral cortex is inversely related to the level of cAMP-dependent protein kinase (cAPK) mediated phosphorylation of kainate-activated receptors/channels. Specifically, when cell cultures were pre-treated with forskolin or dibutyryl cAMP, indirect activators of cAPK, the activity of TPM was abolished, whereas when the cells were pre-treated with H89, an inhibitor of cAPK, the relative activity of TPM was enhanced. The results of this study support the hypothesis that TPM binds to phosphorylation sites on AMPA and kainate receptors, but only in the dephosphorylated state and thereby exerts an allosteric modulatory effect on channel conductance.     

Subclinical form of the American visceral leishmaniasis

The subclinical form of visceral leishmaniasis (VL) shows nonspecific clinical manifestations, with difficulties being frequently met in its clinical characterization and diagnostic confirmation. Thus, the objective of the present study was to define the clinical-laboratory profile of this clinical form. A cohort study was conducted in the state of Maranh?o, Brazil, from January/1998 to December/2000, with monthly follow-up of 784 children aged 0-5 years. Based on the clinical-laboratory parameters reported in the literature, four categories were established, with the children being classified (according to their clinical-evolutive behavior) as asymptomatic (N = 144), as having the subclinical form (N = 33) or the acute form (N = 12) or as subjects "without VL" (N = 595). Multiple discriminant analysis demonstrated that the combination of fever, hepatomegaly, hyperglobulinemia, and increased blood sedimentation rate (BSR) can predict the subclinical form of VL as long as it is not associated with splenomegaly or leukopenia. Subjects with the subclinical form did not show prolonged or intermittent evolution or progression to the acute form of VL. Subclinical cases have a profile differing from the remaining clinical forms of VL, being best characterized by the combination of fever, hepatomegaly, hyperglobulinemia, and increased BSR.     

Histone H2A phosphorylation in DNA double-strand break repair

DNA repair must take place within the context of chromatin, and it is therefore not surprising that many aspects of both chromatin components and proteins that modify chromatin have been implicated in this process. One of the best-characterized chromatin modification events in DNA-damage responses is the phosphorylation of the SQ motif found in histone H2A or the H2AX histone variant in higher eukaryotes. This modification is an early response to the induction of DNA damage, and occurs in a wide range of eukaryotic organisms, suggesting an important conserved function. One function that histone modifications can have is to provide a unique binding site for interacting factors. Here, we review the proteins and protein complexes that have been identified as H2AS129ph (budding yeast) or H2AXS139ph (human) binding partners and discuss the implications of these interactions.     

Isolation of Potentially Pathogenic Escherichia coli O157:H7 from the Ganges River

Escherichia coli serotype O157:H7 was detected among bacteria collected from the Ganges River. O157:H7 isolates tested positive for stx₁, stx₂, and eae gene sequences. Identification of potentially pathogenic isolates from extensively used source water indicates that O157:H7 may be a significant but as yet underacknowledged public health concern in India.     

SOME ULTRASTRUCTURAL EFFECTS OF INSULIN, HYDROCORTISONE, AND PROLACTIN ON MAMMARY GLAND EXPLANTS

The effects of insulin, hydrocortisone, and prolactin on the morphology of explants from midpregnant mouse mammary glands were studied. Insulin promotes the formation of daughter cells within the alveolar epithelium which are ultrastructurally indistinguishable from the parent cells. The addition of hydrocortisone to the medium containing insulin brings the daughter cells to a new, intermediate level of ultrastructural development by effecting an extensive increase of the rough endoplasmic reticulum (RER) throughout the cytoplasm and an increase in the lateral paranuclear Golgi apparatus. When prolactin is added to the insulin-hydrocortisone medium, the daughter cells complete their ultrastructural differentiation. There is a translocation of the RER, Golgi apparatus, and nucleus and the appearance of secretory protein granules within the cytoplasm. There is excellent correlation between the ultrastructural appearance of the alveoli and their capacity to synthesize casein.     

Covert fi− R Factors in fi− R+ Strains of Bacteria

The presence of an fi(-) sex factor can be detected by propagation of the I-specific phage If1. By use of this method of detection, a high proportion of strains with fi(+) R factors were shown also to carry an fi(-) factor which was frequently a second R factor. In some doubly R(+) strains, the fi(+) and the fi(-) factor were observed to be transferred independently at conjugation.     

Shape and size variation: Growth and development of the dusky grouper (Epinephelus marginatus Lowe, 1834)

Demersal fishes have complex life cycles that involve an ontogenetic change in morphology, physiology, and behavior, as their pelagic larval stages colonize benthic habitats. The developmental transition between larvae and juveniles leads to very complex processes of morphogenesis and differentiation. These processes primarily determine changes in external morphology, which is shaped by selective pressures to optimize performance for basic activities such as swimming, escape from predators, and feeding. Fishes have provided fertile grounds for ecomorphological investigations throughout ontogeny, as the role of changing morphology in inducing ontogenetic niche shifts is not always clear. In this framework, some studies have demonstrated that certain species undergo gradual changes, whereas other species experience threshold effects in their ecomorphological relationships during ontogeny. In this study, the intraspecific allometry of the dusky grouper was examined. Geometric morphometric tools were used to quantify shape changes through the development, and a modular approach was also applied to analyze the pattern of covariation between three distinct blocks (head, trunk, and tail). For this purpose, a two‐block Partial Least Square was computed. This method reveals that the pattern of changes in the overall body shape is the result of the modularized changes of these blocks. J. Morphol., 2009. © 2008 Wiley‐Liss, Inc.     

Genome-wide Association Study Identifies Shared Risk Loci Common to Two Malignancies in Golden Retrievers

Dogs, with their breed-determined limited genetic background, are great models of human disease including cancer. Canine B-cell lymphoma and hemangiosarcoma are both malignancies of the hematologic system that are clinically and histologically similar to human B-cell non-Hodgkin lymphoma and angiosarcoma, respectively. Golden retrievers in the US show significantly elevated lifetime risk for both B-cell lymphoma (6%) and hemangiosarcoma (20%). We conducted genome-wide association studies for hemangiosarcoma and B-cell lymphoma, identifying two shared predisposing loci. The two associated loci are located on chromosome 5, and together contribute ~20% of the risk of developing these cancers. Genome-wide p-values for the top SNP of each locus are 4.6×10^-7 and 2.7×10^-6, respectively. Whole genome resequencing of nine cases and controls followed by genotyping and detailed analysis identified three shared and one B-cell lymphoma specific risk haplotypes within the two loci, but no coding changes were associated with the risk haplotypes. Gene expression analysis of B-cell lymphoma tumors revealed that carrying the risk haplotypes at the first locus is associated with down-regulation of several nearby genes including the proximal gene TRPC6, a transient receptor Ca²⁺-channel involved in T-cell activation, among other functions. The shared risk haplotype in the second locus overlaps the vesicle transport and release gene STX8. Carrying the shared risk haplotype is associated with gene expression changes of 100 genes enriched for pathways involved in immune cell activation. Thus, the predisposing germ-line mutations in B-cell lymphoma and hemangiosarcoma appear to be regulatory, and affect pathways involved in T-cell mediated immune response in the tumor. This suggests that the interaction between the immune system and malignant cells plays a common role in the tumorigenesis of these relatively different cancers.