The effects of thermally-induced activity in vivo upon the ultrastructure and Na, K and Cl composition of the epithelial cells of sweat glands from patients with cystic fibrosis

The secretory cells of the fundus of sweat glands from cystic fibrosis (CF) patients had higher Na and Cl contents and showed more granule depletion, cellular disruption and dilated intercellular canaliculi than normal. The cells of the coiled duct also had higher cytoplasmic levels of Na and Cl but were structurally normal. Thermal stimulation produced ultrastructural changes in the CF fundus comparable to normal, including further dilatation of the basolateral clefts, but did not induce the marked changes in the coiled duct which normally occur. The elevated Na and fall in K in the fundus and raised Na and Cl in the coiled duct upon activation, were not observed in the CF glands in which no significant changes were detected.     

Enumeration and isolation of cellulolytic and hemicellulolytic bacteria from human feces

The fibrolytic microbiota of the human large intestine was examined to determine the numbers and types of cellulolytic and hemicellulolytic bacteria present. Fecal samples from each of five individuals contained bacteria capable of degrading the hydrated cellulose in spinach and in wheat straw pretreated with alkaline hydrogen peroxide (AHP-WS), whereas degradation of the relatively crystalline cellulose in Whatman no. 1 filter paper (PMC) was detected for only one of the five samples. The mean concentration of cellulolytic bacteria, estimated with AHP-WS as a substrate, was 1.2 X 10(8)/ml of feces. Pure cultures of bacteria isolated on AHP-WS were able to degrade PMC, indicating that interactions with other microbes were primarily responsible for previous low success rates in detecting fecal cellulolytic bacteria with PMC as a substrate. The cellulolytic bacteria included Ruminococcus spp., Clostridium sp., and two unidentified strains. The mean concentration of hemicellulolytic bacteria, estimated with larchwood xylan as a substrate, was 1.8 X 10(10)/ml of feces. The hemicellulose-degrading bacteria included Butyrivibrio sp., Clostridium sp., Bacteroides sp., and two unidentified strains, as well as four of the five cellulolytic strains. This work demonstrates that many humans harbor intestinal cellulolytic bacteria and that a hydrated cellulose source such as AHP-WS is necessary for their consistent detection and isolation.     

Reproductive performance of dairy cows following treatment with cloprostenol 26 and/or 40 days postpartum: a field trial

One hundred and seventy Holstein Friesian cows were randomly assigned to receive either 500 ug cloprostenol or saline placebo on Day 26 postpartum followed by 500 ug cloprostenol or saline on Day 40 postpartum. Four treatment groups were formed: Group 1 - saline (Day 26)/saline (Day 40); Group 2 - cloprostenol/(Day 26) saline (Day 40); Group 3 - saline (Day 26)/cloprostenol (Day 40); Group 4 - cloprostenol (Day 26)/cloprostenol (Day 40). Double blind techniques were used in administering treatments and in assessing the response to treatment. Palpation of the reproductive tract per tectum and uterine biopsies were performed on 92 cows prior to each treatment at Day 26 and Day 40 postpartum. Progesterone concentrations were determined on milk samples collected prior to treatment. There were no significant differences among treatment groups with respect to services per conception, number of heats detected before first service and culling for infertility. Cloprostenol treatment at Day 26 appeared to delay the first estrus, but it reduced the number of days to conception after the first service. Cows receiving cloprostenol at Days 26 and/or 40 had a decreased calving-to-conception interval compared to controls (P = 0.01). Sequential therapy with two doses of cloprostenol resulted in slightly better reproductive performance than either treatment on Day 26 or 40 alone. Treatment with cloprostenol resulted in a decrease in the subsequent incidence of pyometra (P < 0.05). It is concluded that in the herd studied, cloprostenol therapy at Day 26 and/or 40 postpartum was beneficial to reproductive performance. Although it was anticipated that cloprostenol would be more effective in cows with elevated progesterone levels, the opposite was observed at the Day 26 cloprostenol treatment. Uterine biopsy at Days 26 and/or 40 had a detrimental effect on subsequent reproductive performance.     

The characterization of a monovalent cation-selective channel of mammalian cardiac muscle sarcoplasmic reticulum

Summary Rabbit cardiac muscle sarcoplasmic reticulum (SR) was isolated and separated into ryanodine-sensitive and-insensitive fractions (L.R. Jones and S.E. Cala,J. Biol. Chem. 256:11809–11818, 1981). Vesicles of cardiac SR were incorporated into planar phospholipid bilayers by fusion and the channel activity of the membrane studied under voltage-clamp conditions (C. Miller,J. Membrane Biol. 40: 1–23, 1978). Both fractions contain a monovalent cation-selective three-state channel. In the presence of 75mm K₂SO₄, the fully open state () conductance of this channel is 157.2±30 pS and the sub-state () conductance is 100.7±21 pS. Both open states display the same selectivity sequence for monovalent cations, i.e. K⁺>NH ₄ ⁺ >Rb⁺>Na⁺>Li⁺ and may be blocked by the skeletal muscle relaxants decamethonium and hexamethonium. Block occurs when the compounds are added to either side of the membrane. The properties of the cardiac SR cation channel are compared with those of the previously reported monovalent cation-selective channels of mammalian and amphibian skeletal muscle SR.     

Characterization of Allozyme Null and Low Activity Alleles from Two Natural Populations of DROSOPHILA MELANOGASTER

Null and low enzyme activity alleles recovered from two natural populations were analyzed for a number of genetic and biochemical properties. Analysis of 58 mutations at 14 loci showed that all but one allele were genetically viable and fertile, four alleles were associated with chromosome rearrangements, 28 alleles retained some enzyme activity, 13 alleles formed an active heterodimer with active alleles and five alleles showed partial interallelic complementation. Available evidence indicates that this sample includes mutations resulting from lesions in both coding and regulatory sequences. Certain mutations may be caused by transposable element insertions.     

Donnan potentials from striated muscle liquid crystals. A-band and I-band measurements.

A-band and I-band potentials are measured selectively in crayfish skinned long-tonic muscle fibers. The microelectrode tip diameters used in this study are shown to be sufficiently small to permit the discrete placement of an electrode into either an A-band or I-band. Random and directed impalements into mechanically skinned fibers with microelectrodes yields reproducible trimodal distributions of potentials where the modalities represent the A-band (-1.80 mV), the I-band (-0.76 mV), and the Z-line vicinity (-3.63 mV). In conjunction with Donnan equilibrium theory, fixed charge concentrations are calculated from the measured potentials for the A-band (25.9 mmol e-/l), I-band (10.9 mmol e-/l), and Z-line vicinity (52.3 mmol e-/l). When skinned fibers are treated with Triton X-100, the mean potentials (and charge concentrations) decrease: A-band to -1.71 mV (24.6 mmol e-/l), I-band to -0.71 mV (10.2 mmol e-/l), and the Z-line vicinity to -3.40 mV (49.0 mmol e/l). In the A-band this represents a loss of 1.3 mmol e-/l while in the I-band 0.7 mmol e-/l are lost; both decreases are attributed to the removal of internal membranous structures. In the rigor condition the A-band increases to -2.18 mV (33.1 mmol e-/l) and the I-band increases to -0.88 mV (13.3 mmol e-/l). Relative to the relaxed condition, this represents an increase of 8.5 mmol e-/l and 3.1 mmol e-/l in the A-band and I-band, respectively. The evidence shows that it is practical to measure A-band and I-band potentials selectively. Further, it is demonstrated that similar measurements can be obtained from agar, another polyelectrolyte gel system (see Appendix).     

An Efficient Multiple-Testing Adjustment for eQTL Studies that Accounts for Linkage Disequilibrium between Variants

Methods for multiple-testing correction in local expression quantitative trait locus (cis-eQTL) studies are a trade-off between statistical power and computational efficiency. Bonferroni correction, though computationally trivial, is overly conservative and fails to account for linkage disequilibrium between variants. Permutation-based methods are more powerful, though computationally far more intensive. We present an alternative correction method called eigenMT, which runs over 500 times faster than permutations and has adjusted p values that closely approximate empirical ones. To achieve this speed while also maintaining the accuracy of permutation-based methods, we estimate the effective number of independent variants tested for association with a particular gene, termed M_eff, by using the eigenvalue decomposition of the genotype correlation matrix. We employ a regularized estimator of the correlation matrix to ensure M_eff is robust and yields adjusted p values that closely approximate p values from permutations. Finally, using a common genotype matrix, we show that eigenMT can be applied with even greater efficiency to studies across tissues or conditions. Our method provides a simpler, more efficient approach to multiple-testing correction than existing methods and fits within existing pipelines for eQTL discovery.     

Dynamic habitat suitability modelling reveals rapid poleward distribution shift in a mobile apex predator

Many taxa are undergoing distribution shifts in response to anthropogenic climate change. However, detecting a climate signal in mobile species is difficult due to their wide‐ranging, patchy distributions, often driven by natural climate variability. For example, difficulties associated with assessing pelagic fish distributions have rendered fisheries management ill‐equipped to adapt to the challenges posed by climate change, leaving pelagic species and ecosystems vulnerable. Here, we demonstrate the value of citizen science data for modelling the dynamic habitat suitability of a mobile pelagic predator (black marlin, Istiompax indica) within the south‐west Pacific Ocean. The extensive spatial and temporal coverage of our occurrence data set (n = 18 717), collected at high resolution (~1.85 km²), enabled identification of suitable habitat at monthly time steps over a 16‐year period (1998–2013). We identified considerable monthly, seasonal and interannual variability in the extent and distribution of suitable habitat, predominately driven by chlorophyll a and sea surface height. Interannual variability correlated with El Nino Southern Oscillation (ENSO) events, with suitable habitat extending up to ~300 km further south during La Nina events. Despite the strong influence of ENSO, our model revealed a rapid poleward shift in the geometric mean of black marlin habitat, occurring at 88.2 km decade^?1. By incorporating multiple environmental factors at monthly time steps, we were able to demonstrate a rapid distribution shift in a mobile pelagic species. Our findings suggest that the rapid velocity of climate change in the south‐west Pacific Ocean is likely affecting mobile pelagic species, indicating that they may be more vulnerable to climate change than previously thought.