Effects of 4- and 8-h preexercise feedings on substrate use and performance

Seven well-trained male cyclists were studied during 105 min of cycling (65% of maximal oxygen uptake) and a 15-min "performance ride" to compare the effects of 4- and 8-h preexercise carbohydrate (CHO) feedings on substrate use and performance. A high CHO meal was given 1) 4-h preexercise (M-4), 2) 8-h preexercise (M-8), 3) 4-h preexercise with CHO feedings during exercise (M-4CHO), and 4) 8-h preexercise with CHO feedings during exercise (M-8CHO). Blood samples were obtained at 0, 15, 60, 105, and 120 min and analyzed for lactate, glucose, insulin, and glycerol. Total work output during the performance ride was similar for the M-4 (217,893 +/- 13,348 N/m) and M-8 trials (216,542 +/- 13,905) and was somewhat higher for the M-4CHO (223,994 +/- 14,387) and M-8CHO (224,702 +/- 15,709) trials (P = 0.059, NS). Glucose was significantly elevated throughout exercise, and insulin levels were significantly elevated at 15 and 60 min during M-4CHO and M-8CHO compared with M-4 and M-8 trials. Glycerol levels were significantly lower during the CHO feeding trials compared with placebo and were not significantly different during exercise when the subject had fasted an additional 4 h. The results of this study suggest that when preexercise meals are ingested 4 or 8 h before submaximal cycling exercise, substrate use and performance are similar.     

The influence of topography and pasture management on soil characteristics and herbage accumulation in hill pasture in the North Island of New Zealand

The aim of this study was to examine long-term effects of fertiliser and livestock management and micro-topographical variation on soil physical and chemical characteristics and herbage accumulation on a hill site in the southern North Island of New Zealand.Paddocks subjected to high fertility-high stocking rate (HH) and low fertility-low stocking rate (LL) treatments dating back to 1975 were used. Soil samples were taken from three slope categories (0–12° low slope, LS; 13–25° medium slope, MS; >25° high slope, HS) from HH and LL and a range of soil chemical and physical features were assessed. Herbage accumulation (green matter and dead matter) was measured over 12 months on each microsite.Greater differences in soil and herbage features, such as unsaturated hydraulic conductivity (K_unsat), bulk density (BD), water holding capacity (VSM), soil compressibility (SC), total soil nitrogen (Total-N), Olsen-P and green dry matter accumulation (GDMA), were measured across slope categories than between management treatments, possibly because slope effects on soils would have operated over longer periods of time than the fertiliser-stocking rate contrasts. Increasing slope decreased GDMA on the site, as well as Total-N, Olsen-P, VSM and SC, but increased K_unsat, BD and soil rebound after compression (SR). Slope, VSM, K_unsat, SC, BD and Total-N were the soil variables with largest influence on differentiation between microsites. Olsen-P and SR were less important. Green dry matter accumulation was strongly influenced by slope, soil VSM and K_unsat, and to a lesser extent by soil Total-N and Olsen-P.     

Surveys reveal a complex association of phytoplasmas and viruses with the blueberry stunt disease on Canadian blueberry farms

Surveys for phytoplasmas and viruses were conducted during September 2014 and 2015 on highbush blueberry farms in the Région Montérégie, Quebec. Total DNA and RNA were extracted from blueberry bushes showing blueberry stunt (BBS) symptoms and from symptomless blueberry bushes, and utilised as templates for PCR and RT‐PCR assays, respectively. Phytoplasma DNA was amplified with universal phytoplasma primers that target the 16S rRNA, secA and secY genes from 12 out of 40 (30%) plants tested. Based on 16S rRNA, secA and secY gene sequence identity, phylogenetic clustering, actual and in silico RFLP analyses, phytoplasma strains associated with BBS disease in Quebec were identified as ‘Candidatus Phytoplasma asteris’‐related strains, closely related to the BBS Michigan phytoplasma strain (16SrI‐E). The secY gene sequence‐based single nucleotide polymorphism analysis revealed that one of the BBS phytoplasma strains associated with a leaf marginal yellowing is a secY‐I RFLP variant of the subgroup 16SrI‐E. Two viruses were detected in blueberry bushes. The Blueberry Red Ringspot Virus (BRRV) was found in a single infection in the cultivar Bluecrop with no apparent typical BRRV symptoms. The Tobacco Ringspot Virus (TRSV) was found singly infecting blueberry plants and co‐infecting a BBS phytoplasma‐infected blueberry cv. Bluecrop plant. This is the first report of TRSV in the cv. Bluecrop in Quebec. The Quebec BBS phytoplasma strain was identified in the leafhopper Graphocephala fennahi, which suggests that G. fennahi may be a potential vector for the BBS phytoplasma. The BBS disease shows a complex aetiology and epidemiology; therefore, prompt actions must be developed to support focused BBS integrated management strategies.     

Primate digestion: Interactions among anatomy,physiology, and feeding ecology

Food is vital for life. It provides nutrients for growth, maintenance, and reproduction, and is the source of energy that drives the chemical reactions occurring in every cell.^1,2 However, most food, as it is initially procured, is not in a form suitable for use; it must first be broken down so that it can be transported through cell membranes.¹ The breaking down of food molecules via a system of both mechanical and chemical processes so that they are of use to the body is called digestion.^2,3 © 1998 Wiley-Liss, Inc.     

Impediments to replication fork movement: stabilisation, reactivation and genome instability

Maintaining genome stability is essential for the accurate transmission of genetic material. Genetic instability is associated with human genome disorders and is a near-universal hallmark of cancer cells. Genetic variation is also the driving force of evolution, and a genome must therefore display adequate plasticity to evolve while remaining sufficiently stable to prevent mutations and chromosome rearrangements leading to a fitness disadvantage. A primary source of genome instability are errors that occur during chromosome replication. More specifically, obstacles to the movement of replication forks are known to underlie many of the gross chromosomal rearrangements seen both in human cells and in model organisms. Obstacles to replication fork progression destabilize the replisome (replication protein complex) and impact on the integrity of forked DNA structures. Therefore, to ensure the successful progression of a replication fork along with its associated replisome, several distinct strategies have evolved. First, there are well-orchestrated mechanisms that promote continued movement of forks through potential obstacles. Second, dedicated replisome and fork DNA stabilization pathways prevent the dysfunction of the replisome if its progress is halted. Third, should stabilisation fail, there are mechanisms to ensure damaged forks are accurately fused with a converging fork or, when necessary, re-associated with the replication proteins to continue replication. Here, we review what is known about potential barriers to replication fork progression, how these are tolerated and their impact on genome instability.     

Preliminary studies of Eutorna phaulocosma (Lepidoptera: Oecophoridae) in New Zealand

Abstract

In 1978 George C. Williams predicted that the last two decades of this century would be a fabulous age, and that evolutionary biology would provide critical insights into the processes of change in the biological world. He suggested that these might come to be described as the “good old days”. I am not so sure that this is likely, but I am very sure that it will be a turbulent time. I think also that those biologists who attended the recent SYSTANZ meeting on evolution must by now be equally convinced. The conference was punctuated by heated debates on major topics such as Darwinian and neo-Darwinian theory, vicariance biogeography, and teleology, to mention but a few.     

Isolation and characterisation of an antifolate insensitive (afi1) mutant of Arabidopsis thaliana

Antifolates can impair the synthesis and/or function of folates in living organisms. Mechanisms of resistance or tolerance to antifolates have been mainly described in plants using the drug methotrexate. In this work, the antifolate trimethoprim (TMP) was used with the aim of revealing a novel mechanism of resistance. EMS mutagenised seeds from Arabidopsis were screened to isolate individuals insensitive to TMP. Genetic analysis revealed a homozygous recessive mutation that segregates with the phenotype of tolerance to 50 μm TMP. Mapping analysis localised the mutation at the end of the short arm of chromosome 3. Preliminary characterisation demonstrated up‐regulation of several genes from the folate biosynthetic pathway in the TMP insensitive mutant, and a slight increase in total folate content in the mutant as compared with the Col‐0 control. Moreover, sequence analysis of the DHFR (dihydrofolate reductase) genes, which encode a known target for resistance to antifolates, did not reveal any changes. This study is the first report of a stable mutant insensitive (afi1) to the antifolate trimethoprim in plants, and suggests the existence of a novel mechanism of resistance to antifolates.     

Genotypic and phenotypic properties of <Emphasis Type="Italic">Candida parapsilosis</Emphasis><Emphasis Type="Italic">sensu strictu</Emphasis> strains isolated from different geographic regions and body sites

Background  

Candida parapsilosis is known to show limited genetic variability, despite different karyotypes and phenotypes have been described. To further investigate this aspect, a collection of 62 sensu strictu C. parapsilosis independent isolates from 4 geographic regions (Italy, n = 19; New Zealand, n = 15; Argentina, n = 14; and Hungary, n = 14) and different body sites (superficial and deep seated) were analysed for their genetic and phenotypic traits. Amplification fragment length polymorphism (AFLP) analysis was used to confirm species identification and to evaluate intraspecific genetic variability. Phenotypic characterisation included clinically relevant traits, such as drug susceptibility, in vitro biofilm formation and aspartyl protease secretion.     

Absence of prejunctional sympathetic effect of amiodarone in hearts of open-chest anesthetized dogs

The effect of amiodarone (30 mg/kg p.o. each day for 3 weeks) on noradrenaline (NA) overflow into coronary sinus (CS) blood during left stellate stimulation (15 V, 2-ms square waves, 30 s duration at 1, 2, 4, and 8 Hz in random order) was investigated in an open-chest dog preparation. CS blood samples were taken before and during the stimulation period for plasma NA and hematocrit determinations. CS blood flow was monitored (extracorporal circulation with an electromagnetic flow meter) and used for NA output computation. The right atrium was paced throughout the experimental period. However, because AV block occurred at a high pacing rate in some amiodarone-treated dogs, pacing rate was lower in that group than in control dogs (132 +/- 13 vs. 161 +/- 10 min-1, ns). Mean arterial pressure was also lower in the treated group (95 +/- 9 vs. 110 +/- 13 mmHg, but increased in every dog upon stimulation (p less than 0.05). Basal left ventricular dP/dtmax was comparable in the two groups of dogs and increased in a similar fashion upon stimulation (p less than 0.05). The increase in plasma NA concentration upon stimulation was comparable between the control and the amiodarone-treated group (0.38 +/- 0.08 vs 0.40 +/- 0.12 ng/mL at 1 Hz and 12.7 +/- 3.1 vs 11.3 +/- 2.3 ng/mL at 8 Hz, ns). The increase in NA output was also comparable (7.0 +/- 1.6 vs. 10.7 +/- 5.4 ng/min at 1 Hz and 356 +/- 124 vs. 334 +/- 102 ng/min at 8 Hz, ns). Amiodarone did not alter the myocardial NA content. We conclude that amiodarone, administered orally for 3 weeks, does not interfere with neural NA release, or with the positive inotropic response, following sympathetic nerve stimulation in dogs.