Induction of cytochrome P-450-dependent monooxygenase systems in embryos and eleutheroembryos of the killfish Fundulus heteroclitus

Microsomal aryl hydrocarbon hydroxylase (AHH) activity was highly inducible by polychlorinated biphenyls (PCBs) in Fundulus embryos, and stages prior to the appearance of the liver rudiment were competent to respond to these inducers. Consistent with previous observations, basal AHH activity in whole eleutheroembryo microsomes was shown to increase about 9-fold within 24 h of hatching. Aminopyrine N-demethylase (APD) activity also increased with time after hatching. However, the increase in APD activity was much less than that of AHH activity, suggesting a post-hatching change in basal cytochrome P-450 isozyme composition. Also associated with hatching was an increase in the sensitivity to PCBs as inducers of AHH activity. The ED50 for induction of AHH activity in eleutheroembryos was estimated to be only one-third to one-fourth that in embryos. This developmental increase in the sensitivity to PCBs was not due to a redistribution of PCBs between the yolk and tissues with yolk absorption, and was not simply age-dependent, but appeared to require hatching. An additional change in the monooxygenase system associated with hatching was that microsomal NADPH-cytochrome c reductase activity was not inducible by PCBs prior to hatching, but was modestly inducible after hatching. High performance liquid chromatographic (HPLC) analysis of benzo[a]-pyrene (BP) metabolites formed by microsomes from control and PCB-treated eleutheroembryos demonstrated production of dihydrodiols in the 7,8- and 9,10-positions of the benzo-ring. The formation of these metabolites was completely inhibited by the epoxide hydrolase (EH) inhibitor, trichloropropene oxide, indicating the presence of EH in Fundulus eleutheroembryos. Furthermore, these results indicate the Fundulus eleutheroembryos probably can activate BP to its ultimate carcinogenic form, the 7,8-dihydrodiol-9,10-epoxide, and induction of AHH activity by PCBs is likely to increase the rate of formation of activated metabolites from BP and related compounds. However, during the most active period of organogenesis, prior to hatching, basal AHH activity was low, and prehatching stages were relatively insensitive to cytochrome P-450 inducers. The combination of these effects may help to protect these stages from damage from activated metabolites.     

Characterization of the CHORI-240 BAC clones containing the bovineCSN1S1, CSN2, STATH, CSN1S2 andCSN3 genes

Nineteen BAC clones were identified by hybridization of the bovine genomic BAC library CHORI-240 with mixedCSN1S1- andCSN3-specific probes. Two of the clones were shown to contain the genesCSN1S1, CSN1S2, CSN2, STATH andCSN3, and five were proved to include the genesCSN2, STATH, CSN1S2 andCSN3. These data showed that the BAC contig was established for the whole casein cluster, including all known five genes.     

Integrative taxonomy tests possible hybridisation between Central Asian cerambycids (Coleoptera)

Hybridisation can lead to the formation of new evolutionary lineages and some described insect species may in fact be first-generation hybrids of their parental species. Anoplistes forticornis and A. galusoi are two closely related cerambycid taxa endemic to Central Asia that exhibit a peculiar geographical distribution. Although the common diagnostic elytral pattern makes these beetles superficially easily distinguishable, there are marked resemblances in their morphology. By applying an integrative taxonomy approach, we verify the taxonomic status of A. forticornis and A. galusoi and test the possibility of hybridisation. The results of our comprehensive morphological examination and molecular analyses targeting mitochondrial (COI, 16S rRNA) and nuclear (arginine kinase, CAD, 28S rRNA) genes support the specific status of these taxa. In mtDNA, the putative hybrid specimen is more closely related to A. forticornis, which indicates that a female of this species bred with a male of A. galusoi. The supposed ecotypic variability (manifested in elytral pattern) is apparently not related to the topography or spatial structure of habitat. The phylogenetic hypothesis supports a peripatric scenario in which populations of the common ancestor had been separated for a significant period of time, first by the mountain ranges of Dzungarian Alatau (~11–10 Ma) and ultimately by the Ili River. The diverged taxa came into recent secondary contact following these isolation events. The methodology presented herein can be widely applied to identify first-generation hybridisation in Coleoptera.     

Discrepancy between cardiorespiratory system and skeletal muscle in elite cyclists after hypoxic training

BACKGROUND: The purpose of this study was to determine the effects of hypoxic training on the cardiorespiratory system and skeletal muscle among well-trained endurance athletes in a randomized cross-over design. METHODS: Eight junior national level competitive cyclists were separated into two groups; Group A trained under normoxic condition (21% O2) for 2 hours/day, 3 days/week for 3 weeks while Group B used the same training protocol under hypoxic condition (15% O2). After 3 weeks of each initial training condition, five weeks of self-training under usual field conditions intervened before the training condition was switched from NT to HT in Group A, from HT to NT in Group B. The subjects were tested at sea level before and after each training period. O2 uptake (O2), blood samples, and muscle deoxygenation were measured during bicycle exercise test. RESULTS AND DISCUSSION: No changes in maximal workload, arterial O2 content, O2 at lactate threshold and O2max were observed before or after each training period. In contrast, deoxygenation change during submaximal exercise in the vastus lateralis was significantly higher at HT than NT (p < 0.01). In addition, half time of oxygenation recovery was significantly faster after HT (13.2 PlusMinus; 2.6 sec) than NT (18.8 PlusMinus; 2.7 sec) (p < 0.001). CONCLUSIONS: Three weeks of HT may not give an additional performance benefit at sea level for elite competitive cyclists, even though HT may induce some physiological adaptations on muscle tissue level.