Metabolic changes following eccentric exercise in trained and untrained men

The effects of one 45-min bout of high-intensity eccentric exercise (250 W) were studied in four male runners and five untrained men. Plasma creatine kinase (CK) activity in these runners was higher (P less than 0.001) than in the untrained men before exercise and peaked at 207 IU/ml 1 day after exercise, whereas in untrained men the maximum was 2,143 IU/ml 5 days after exercise. Plasma interleukin-1 (IL-1) in the trained men was also higher (P less than 0.001) than in the untrained men before exercise but did not significantly increase after exercise. In the untrained men, IL-1 was significantly elevated 3 h after exercise (P less than 0.001). In the untrained group only, 24-h urines were collected before and after exercise while the men consumed a meat-free diet. Urinary 3-methylhistidine/creatinine in the untrained group rose significantly from 127 mumol/g before exercise to 180 mumol/g 10 days after exercise. The results suggest that in untrained men eccentric exercise leads to a metabolic response indicative of delayed muscle damage. Regularly performed long distance running was associated with chronically elevated plasma IL-1 levels and serum CK activities without acute increases after an eccentric exercise bout.     

Large scale selection of aluminum-resistant mutants from plant cell culture: expression and inheritance in seedlings

Summary A large number of aluminum-resistant variants, selected from non-mutagenized homozygous diploid cell cultures of Nicotiana plumbaginifolia Viv., are characterized. Of 115 variants cloned and reselected from single cells, 67 retained Al resistance in callus cultures after 6–9 months of growth in the absence of Al. There was no association between Al resistance and callus growth in the absence of Al, suggesting that the Al-resistant phenotype is not detrimental in the absence of Al challenge and that Al resistance is not the result of increased vigor. Plants regenerated from initially resistant callus lines that subsequently lost their resistance failed, with one exception, to transmit resistance to their seedling progeny. Fertile plants were regenerated from 40 of the 67 variants that retained stable Al resistance in callus culture. All 40 transmitted Al resistance to their seedling progeny (selfed and backcrossed) in segregation ratios expected for a single dominant mutation. The selfed progeny of many variants also segregated for recessive lethal mutations which were attributed to independent mutations that occurred during cell culture.     

Regional localisations and linkage relationships of seven RFLPs and myotonic dystrophy on chromosome 19

Summary We have studied the genetic linkage relationships of seven DNA polymorphisms on chromosome 19, with each other and with the myotonic dystrophy locus. The DNA sequences were localised to various regions of the chromosome using translocations in somatic cell hybrids. These results provide the basis for a linkage map of most of chromosome 19, and suggest that the myotonic dystrophy locus is close to the centromere.     

Culture duration alters the glutathione content and sensitivity to ethacrynic acid of rat hepatocyte monolayer cultures

Many of the differentiated functions of hepatocytes are lost in culture, yet addition of certain medium supplements can aid in the retention of differentiated character. Therefore, the effect of time in monolayer culture on rat hepatocyte glutathione (GSH) synthesis and sensitivity to the GSH detoxicated xenobiotic ethacrynic acid was examined in cultures with and without medium supplementation by transferrin and sodium selenite. GSH content was found to be about 12 nmol/µg DNA at 4 hr in culture and to approximately triple by 24 hr. Intracellular GSH levels continued to increase in transferrin/sodium selenite-supplemented cultures, from 32 to 41.6 nmol/µg DNA, while GSH levels in unsupplemented cultures declined to 18 nmol/µg DNA. However, the rate of GSH synthesis after diethylmaleate depletion was found to decrease from 4.2 to 2.8 nmol/hr/µg DNA at 4 and 24 hr after inoculation, respectively. GSH repletion rate increased to 3.9 nmol/hr/µg DNA at 48 hr. The GSH accumulation rate after depletion in supplemented cultures did not vary significantly over the initial 48 hr. Incubation for 3 hr with 100 µM ethacrynic acid (EA) did not elicit an increase in LDH leakage in hepatocyte monolayers after 4 or 48 hr in culture or in cultures with supplemented medium at any time point tested. Cultures 24 hr in medium without transferrin/sodium selenite supplementation exhibited significant LDH leakage after 3 hr of EA treatment. Over the 3 hr EA treatment, intracellular GSH content was decreased in all cultures. Only in the 24 hr unsupplemented cultures did GSH depletion exceed the 90% level previously associated with depletion of the mitochondrial pool of GSH and EA toxicity in hepatocytes. The experiments show that during the redifferentiation of hepatocytes in culture, a transient period occurs when apparent GSH synthesis is depressed and enhanced sensitivity to GSH-detoxicated compounds is observed. This period of increased sensitivity is prevented or at least delayed by inclusion of supplemental transferrin and sodium selenite, suggesting that redifferentiation can be regulated by extracellular influences.Abbreviations CYSSG cysteine-glutathione mixed disulfide - DEM diethyl maleate - EA ethacrynic acid - GSH reduced glutathione - GSSG oxidized glutathione - HBS HEPES buffered saline - HWME hepatocyte Williams' Medium E (WME with insulin, corticosterone and 0.5 mM methionine) - LDH lactate dehydrogenase - TS-HWME transferrin/sodium selenite-supplemented HWME - WME Williams' Medium E     

Chlortetracycline and Oxytetracycline Residues in Poultry Tissues and Eggs

A pad-plate method of assaying residual amounts of chlortetracycline (CTC) and oxytetracycline (OTC) using Bacillus cereus 213 was used to determine amounts of antibiotic left in tissues and eggs of poultry fed 1,000 and 200 ppm of CTC and OTC in basal feed mixtures. The effects of various methods of cooking the tissues and eggs and the potentiating effect of terephthalic acid (TPA) were studied. It was found that normal methods of roasting, frying, and autoclaving poultry tissue destroyed all residual CTC and OTC, even with the potentiating effect of TPA. The largest amounts of residual antibiotic were found in the liver, then breast, and then thigh tissue when assayed for CTC. Tissue assays for CTC revealed that it was not taken up as extensively as CTC and the largest amounts were found in the liver, then breast. OTC residue was seldom found in the thigh tissue. Terephthalic acid in 0.5% concentration increased the concentration found in all cases. Cooking by poaching and scrambling eggs did not destroy the antibiotic in all cases.     

Consortships and conceptions in captive rhesus macaques (Macaca mulatta)

A captive group of rhesus macaques (Macaca mulatta) was observed during the breeding season to determine if consortship behavior, rather than promiscuous matings, resulted in higher reproductive success for either partner. The 38 adult females in this group were observed “in consort” with the 5 adult or 4 subadult males on 179 occasions. Most of these consortships were short-term, lasting less than one day. Six females engaged in consortships with one male that spanned more than three days, but the majority of these long-term associations did not result in a pregnancy with that male. The term “consortship” has been traditionally accepted as a specific nonhuman primate mating pattern, but the exact nature of this behavioral pattern and its evolutionary importance have been less clearly understood. Consort behavior could be considered a precursor to a monogamous mating system if long-term exclusive sexual associations resulted in higher reproductive success for the participants. But this study demonstrates that for rhesus macaques, who exhibit both consort behavior and more promiscuous matings, there is no clear reproductive advantage to long-term consortships. In light of the inconsistent use of the term consortship, the possible adaptive significance of an exclusive male-female sexual association for the evolution of human mating patterns needs to be reevaluated.     

A Protein Kinase-Dependent Block to Reinitiation of DNA Replication in G2 Phase in Mammalian Cells

Eukaryotic cells normally replicate their DNA only once between mitoses. Unlike G1 nuclei, intact G2 nuclei do not replicate during incubation inXenopusegg extract. However, artificial permeabilization of the nuclear membrane of G2 nuclei allows induction of new initiations byXenopusegg extract. This is consistent with the action of a replication licensing factor which is believed to enter the nucleus when the nuclear membrane breaks down at mitosis. Here, we show that G2 nuclei will initiate a new round of replication in the absence of nuclear membrane permeabilization, if they are preexposed to protein kinase inhibitorsin vivo.Competence to rereplicate is generated within 30 min of drug treatment, well before the scheduled onset of mitosis. This demonstrates that a protein kinase-dependent mechanism is continually active in G2 phase to actively prevent regeneration of replication capacity in mammalian cells. Kinase inhibition in G2 cells causes nuclear accumulation of replication protein A. Rereplication of kinase-inhibited G2 nuclei also depends on factors supplied byXenopusegg extract, which are distinct from those required for replication licensing.