An assessment of shallow and mesophotic reef brachyuran crab assemblages on the south shore of O‘ahu,Hawai‘i

Shallow coral reefs are extensively studied but, although scleractinian corals have been recorded to 165 m, little is known about other mesophotic coral reef ecosystem (MCE) inhabitants. Brachyuran crabs fill many ecological and trophic niches on reefs, making them ideal candidates for evaluating species composition among depths to ask whether MCEs host the same communities as shallower reef communities that have been well studied. Here we deployed autonomous reef monitoring structures for 2 yr on the south shore of O‘ahu along a depth gradient (12, 30, 60, and 90 m) to sample and assess brachyuran crab communities. A total of 663 brachyuran crabs representing 69 morphospecies (16 families) were found. Community composition was not significantly different within depths, but was highly stratified by depth. Each depth was distinct, but the 30 and 60 m depths were least dissimilar from one another. We show that deeper reefs host significantly different brachyuran communities, and at much lower total abundance, than shallow reefs in Hawai‘i, with 4–27 unique morphospecies per depth and only 3 of 69 morphospecies (~4 %) occurring across the entire depth range sampled.     

Chloramphenicol and Ampicillin-Induced Changes in Rat Hepatic Esterase and Amidase Activities

The influence of ampicillin and chloramphenicol administered intraperitoneallysingly or in combination on the protein content and the activities of hepaticsterase and amidase have been investigated in rats. The results have beencompared to the effects of phenobarbitone (inducer) andp-nitrophenyl-phosphate (inhibitor) of hepatic hydrolases.Ampicillin pretreatment reduced protein level and amidase activity by3.5% each but caused a significant increase (8.1%) in total esteraseactivity compared to controls. Chloramphenicol treatment caused an overalldecrease in protein level, esterase and amidase activities respectively by11%, 11%, and 35% over controls.Combined administration of both drugs resulted in a decrease in protein,esterase and amidase activities by 11.5%, 12.5%, and 41.2% respectively,thus mimicking the effects obtained with chloramphenicol alone.The changes induced by administration of the drugs particularly incombination on the constituent enzymes of rat hepatic hydrolases may affectthe ability of the body to deal with exposure to environmental chemicals ifextrapolated to man.     

Modification of BRCA1-associated breast cancer risk by the polymorphic androgen-receptor CAG repeat

Compared with the general population, women who have inherited a germline mutation in the BRCA1 gene have a greatly increased risk of developing breast cancer. However, there is also substantial interindividual variability in the occurrence of breast cancer among BRCA1 mutation carriers. We hypothesize that other genes, particularly those involved in endocrine signaling, may modify the BRCA1-associated age-specific breast cancer risk. We studied the effect of the CAG repeat-length polymorphism found in exon 1 of the androgen-receptor (AR) gene (AR-CAG). AR alleles containing longer CAG repeat lengths are associated with a decreased ability to activate androgen-responsive genes. Using a sample of women who inherited germline BRCA1 mutations, we compared AR-CAG repeat length in 165 women with and 139 women without breast cancer. We found that women were at significantly increased risk of breast cancer if they carried at least one AR allele with >/=28 CAG repeats. Women who carried an AR-CAG allele of >/=28, >/=29, or >/=30 repeats were given a diagnosis 0.8, 1.8, or 6.3 years earlier than women who did not carry at least one such allele. All 11 women in our sample who carried at least one AR-CAG allele with >/=29 repeats had breast cancer. Our results support the hypothesis that age at breast cancer diagnosis is earlier among BRCA1 mutation carriers who carry very long AR-CAG repeats. These results suggest that pathways involving androgen signaling may affect the risk of BRCA1-associated breast cancer.     

BMP signalling inhibits premature neural differentiation in the mouse embryo

The specification of a subset of epiblast cells to acquire a neural fate constitutes the first step in the generation of the nervous system. Little is known about the signals required for neural induction in the mouse. We have analysed the role of BMP signalling in this process. We demonstrate that prior to gastrulation, Bmp2/4 signalling via Bmpr1a maintains epiblast pluripotency and prevents precocious neural differentiation of this tissue, at least in part by maintaining Nodal signalling. We find that during gastrulation, BMPs of the 60A subgroup cooperate with Bmp2/4 to maintain pluripotency. The inhibition of neural fate by BMPs is independent of FGF signalling, as inhibition of FGF signalling between 5.5 and 7.5 days post-coitum does not block neural differentiation in the mouse embryo. Together, our results demonstrate that inhibition of BMP signalling has a central role during neural induction in mammals and suggest that FGFs do not act as neural inducers in the post-implantation mouse embryo.     

Molecular and Immunologic Characterization of Gynogenetic Channel Catfish (Ictalurus punctatus)

Second-generation gynogenetic channel catfish were characterized by molecular and immunologic assays to determine if they were isogenic at major histocompatibility complex loci. Southern blot analyses, using channel catfish MHC class II B and class I A gene probes, revealed identical banding patterns among second-generation gynogenetic fish. In contrast, banding patterns from outbred fish differed not only from gynogenetic animals, but also among themselves. Nucleotide sequence analysis of the MHC class II β₁ domain, which encompasses the peptide binding region, from four randomly selected gynogenetic fish showed a single DNA sequence. In contrast, analysis of the same region from three outbred fish showed sequences that differed not only among themselves, but also from those of gynogenetic animals. In cytotoxic assays, peripheral blood leukocytes from outbred fish lysed both gynogenetic and allogeneic targets, whereas those from gynogenetic fish lysed only allogeneic targets. Taken together, these results suggest that this group of second-generation gynogenetic channel catfish is isogenic at MHC loci and may provide an excellent system with which to study cell-mediated immunity in teleosts. Received September 11, 1998; accepted January 14, 1999     

Temperature affects insulin-like growth factor I and growth of juvenile southern flounder, Paralichthys lethostigma

Temperature profoundly influences growth of heterothermic vertebrates. However, few studies have investigated the effects of temperature on growth and insulin-like growth factor I (IGF-I) in fishes. The aim of this study was to examine effects of temperature on growth and establish whether IGF-I may mediate growth at different temperatures in southern flounder, Paralichthys lethostigma. In two experiments, juvenile flounder were reared at 23 and 28 degrees C and growth was monitored for either 117 or 197 days. Growth was similar across treatments in both experiments until fish reached approximately 100 mm total length. Body size then diverged with fish at 23 degrees C ultimately growing 65-83% larger than those at 28 degrees C. Muscle IGF-I mRNA, plasma IGF-I, and hepatosomatic index (HSI) were significantly higher in flounder at 23 degrees C, whereas hepatic IGF-I mRNA abundance did not differ with treatment. Muscle IGF-I mRNA was correlated with HSI, while plasma IGF-I was correlated with body size, hepatic IGF-I mRNA, and HSI. These results demonstrate a strong effect of temperature on flounder growth and show that temperature-induced variation in growth is associated with differences in systemic IGF-I and local (i.e., muscle) IGF-I mRNA levels. The results also support the use of plasma IGF-I and HSI as indicators of flounder growth status.     

Enzyme activity evaluation of organic solvent-treated phenylalanine ammonia lyase

The direct one-step synthesis of L-phenylalanine methyl ester in an organic-aqueous biphasic system using phenylalanine ammonia lyase (E.C.4.3.1.5, PAL) containing Rhodotorula glutinis yeast whole cells was reported earlier. We report here further optimization of this biotransformation using isolated PAL, when the lyophilized enzyme is treated with different water miscible and water immiscible organic solvents. Use of isolated PAL enzyme is advantageous in overcoming diffusion barriers encountered when using PAL containing R.glutinis whole cells, and resulted in increased product yield due to better interaction of enzyme with the substrate. Among the water miscible solvents, ethanol treated and methanol-treated enzymes supported maximum PAL forward and reverse activities; respectively. In the water immiscible solvents category, heptane-treated enzyme exhibited maximal activity for both PAL forward and reverse reactions. PAL activity obtained with enzyme specimens treated with methanol, ethanol, and heptane varied in the range of 91–99% of that observed in aqueous buffer medium for the forward reaction; and 89–95% for the reverse reaction. n-butanol,acetone, and benzene were found to have a inhibitory effect on PAL enzyme, in that, it resulted in only 31–33% activity of that obtained with aqueous solution. Raman spectroscopy was used to monitor amide I and II bands which are sensitive to changes in the secondary structure of proteins. No changes in structure could be detected from the analyses of AI and AII bands of PAL spectra. This data obtained for PAL, a tetramer, could be significant in predicting how solvent interactions affect the structure and function of multimeric proteins and enzymes in nonaqueous media.