Thiols and pancreatic beta-cell function: a review

In pancreatic islets insulin secretion in response to a variety of stimulators is sensitive to the redox state of extracellular and intracellular thiols. In this connection variations of plasma glutathione (GSH) may also be of importance. In the process of stimulus-secretion coupling, membrane thiols play an important role. One major localization of critical thiols appears to be related to the influx of calcium through the voltage-dependent channel. Other transmembranal ion movements and the cAMP system seem to be less sensitive to thiol oxidation than calcium influx via voltage-dependent Ca channels.     

牛α1-AT基因5’侧翼区新SNPS的鉴定及其与产奶性状的相关性

以中国荷斯坦奶牛(Chinese Holstein dairy cattle)为对象,以α1 抗胰蛋白酶基因(α1-AT)为候选基因,扩增5′侧翼区668 bp和999 bp的片段并进行测序.首次发现,在+3 142 bp处P1和+4 408 bp处P2分别发生C-T、T-C突变.随后采用PCR-RFLP方法对随机采自6个牛场,共计294头牛进行了检测,遗传变异和产奶性状分析结果显示：2个位点的等位基因在群体中都有分布,且处于中度多态.P1位点A和B等位基因的频率分别为50.34%和49.66%; AA、AB和BB基因型频率分别为23.81%、53.06%和23.13%;P2位点E和F等位基因的频率分别为30.61%和69.39%, EE、EF和FF基因型频率分别为11.90%、37.41%和50.68%. χ2适合性检验表明,该群体在P1位点的突变达到Hardy-Weinberg平衡状态（P>0.05）,在P2位点未达到平衡.基因与产奶性状关联分析表明,AB基因型个体产奶量与脂蛋比显著高于AA基因型个体(P＜0.05);FF基因型个体乳蛋白率显著高于EF基因型个体(P＜0.05);9种单倍型组合与乳脂率、乳蛋白率、体细胞数、产奶量及脂蛋比均存在不同程度相关性.     

The importance of ‘tooglies’ to the ethnography of F.E. Williams,government anthropologist

The theoretical orientation, encapsulated in the semi‐serious concept of ‘tooglies'of F.E. Williams, government anthropologist for the Territory of Papua in the inter‐war period, is considered. His ideas about culture change are contrasted with those of Bronislaw Malinowski, who acted as his mentor at one time. His treatment of the social organisational anomaly of Sogeri Koiari ‘sex affiliation’, often cited as a case of parallel bilineal descent, is compared with Margaret Mead's analysis of the ‘Mundugumor ropes’, which is classed as the opposite, cross‐sex bilineal descent. It is shown that Williams was able to get a clearer insight into this anomalous data than Mead and Fortune, and, on the whole, worked with an understanding of culture and Papuan social organisation that presages the relational approach of today.     

EFFECTS OF VARIATIONS IN LIGHT INTENSITY ON THE EFFICIENCY OF GROWTH OF SKELETONEMA COSTATUM (BACILLARIOPHYCEAE) IN A CYCLOSTAT1

The relative importance of respiration and organic carbon release to the efficiency of carbon specific growth of Skeletonema costatum (Grev.) Clave was evaluated over a light range from 1500–15 μE · m^?2· s^?1. Net growth efficiency ranged from 0.45–0.69 with a maximum at 130 μE · m^?2· s^?1. Respiration was 93% or more of the variations in growth efficiency. Organic carbon release ranged from 0–7% of gross production and increased with light intensity. Carbon specific particulate production was a hyperbolic function of incident light intensity and was related exponentially to particulate carbon production per unit chlorophyll a. Full sunlight conditions, 1500 μE · m^?2· s^?1, did not induce photoinhibition of gross production. Variations in the efficiency of growth of S. costatum were minimized over a wide range of light intensities mainly because of variations in cellular pigments which permitted the efficient utilization of available light energy, and a reduction in the losses of carbon which increases the growth rate, possibly as a consequence of the recycling of respired carbon within the cell.     

Isolation of Primary Myofibroblasts from Mouse and Human Colon Tissue

The myofibroblast is a stromal cell of the gastrointestinal (GI) tract that has been gaining considerable attention for its critical role in many GI functions. While several myofibroblast cell lines are commercially available to study these cells in vitro, research results from a cell line exposed to experimental cell culture conditions have inherent limitations due to the overly reductionist nature of the work. Use of primary myofibroblasts offers a great advantage in terms of confirming experimental findings identified in a cell line. Isolation of primary myofibroblasts from an animal model allows for the study of myofibroblasts under conditions that more closely mimic the disease state being studied. Isolation of primary myofibroblasts from human colon tissue provides arguably the most relevant experimental data, since the cells come directly from patients with the underlying disease. We describe a well-established technique that can be utilized to isolate primary myofibroblasts from both mouse and human colon tissue. These isolated cells have been characterized to be alpha-smooth muscle actin and vimentin-positive, and desmin-negative, consistent with subepithelial intestinal myofibroblasts. Primary myofibroblast cells can be grown in cell culture and used for experimental purposes over a limited number of passages.     

Photosynthesis of Cockspur [Echinochloa crus-galli (L.) Beauv.] at Sites of Naturally Elevated CO2 Concentration

High abundance of cockspur (Echinochloa crus-galli) at the geothermal carbon dioxide spring area in Staveinci indicates that this species is able to grow under widely varying CO₂ concentrations. Living cockspur plants can even be found very close to gas-releasing vents where growth is significantly reduced. Plant height correlated well with CO₂ exposure. The ¹³C value of the CO₂ spring air was –3.9 and ¹³C values of high-, medium-, and low-CO₂ plants were –10.14, –10.44, and –11.95 , respectively. Stomatal response directly followed the prevailing CO₂ concentrations, with the highest reduction of stomatal conductance in high CO₂ concentration grown plants. Analysis of the curves relating net photosynthetic rate to intercellular CO₂ concentration (P _N-C_i curves) revealed higher CO₂ compensation concentration in plants growing at higher CO₂ concentration. This indicates adjustment of respiration and photosynthetic carbon assimilation according to the prevailing CO₂ concentrations during germination and growth. There was no difference in other photosynthetic parameters measured.     

Effect of iron concentration on hydrogen fermentation

The effect of the iron concentration in the external environment on hydrogen production was studied using sucrose solution and the mixed microorganisms from a soybean-meal silo. The iron concentration ranged from 0 to 4000 mgFeCl₂ l⁻¹. The temperature was maintained at 37°C. The maximum specific hydrogen production rate was found to be 24.0 mlg⁻¹ VSSh⁻¹ at 4000 mgFeCl₂ l⁻¹. The specific production rate of butyrate increased with increasing iron concentration from 0 to 20 mgFeCl₂ l⁻¹, and decreased with increasing iron concentration from 20 to 4000 mgFeCl₂ l⁻¹. The maximum specific production rates of ethanol (682 mgg⁻¹ VSSh⁻¹) and butanol (47.0 mgg⁻¹ VSSh⁻¹) were obtained at iron concentrations of 5 and 3 mgFeCl₂ l⁻¹, respectively. The maximum hydrogen production yield of 131.9 mlg⁻¹ sucrose was obtained at the iron concentration of 800 mgFeCl₂ l⁻¹. The maximum yields of acetate (389.3 mgg⁻¹ sucrose), propionate (37.8 mgg⁻¹ sucrose), and butyrate (196.5 mg g⁻¹ sucros) were obtained at iron concentrations of 3, 200 and 200 mgFeCl₂ l⁻¹, respectively. The sucrose degradation efficiencies were close to 1.0 when iron concentrations were between 200 and 800 mgFeCl₂ l⁻¹. The maximum biomass production yield was 0.283 gVSSg⁻¹ sucrose at an iron concentration of 3000 mgFeCl₂ l⁻¹.     

Photosynthetic Traits in Wheat Grown under Decreased and Increased CO2 Concentration, and after Transfer to Natural CO2 concentration

Wheat plants were grown from sowing to day 18 in 26-dm³ chambers at three different CO₂ concentrations: 150 (-CO₂), 350 (C, control), 800 (+CO₂) mol mol^-1. Afterwards, plants of the three variants were grown at the same natural CO₂ concentration. Plant characteristics were measured just before the transfer (0 days after CO₂ treatment, DAT), and at 5 – 8 DAT on the 1^st leaf, and at 12 – 22 DAT on the 4^th leaf. Decreased or increased CO₂ concentrations caused acclimations which persisted after transplantation to natural CO₂ concentration. At 5 – 8 DAT, stomatal density, stomatal conductance (g_s), CO₂ saturated net photosynthetic rate (P_Nsat0), radiation saturated net photosynthetic rate (P_Nsat1), and carboxylation efficiency () were higher in -CO₂ plants and lower in +CO₂ plants than in C plants. As compared with C plants, the photochemical efficiency () was lower in -CO₂ and higher in -CO₂ plants, however, chlorophyll (Chl) a, Chl b, Chl a–b and carotenoid contents were lower in both -CO₂ and +CO₂ plants. On the 4^th leaf, which emerged on plant after finishing CO₂ treatments, at 12 – 22 DAT, no differences in stomatal density and g, between treatments were observed. In -CO₂ plants, pigment content and P_Nsat0 were higher, was lower, and P_Nsat1 and were not different from C plants. In contrast, in +CO₂ plants, pigment content, P_Nsat1 and were lower, and P_Nsat0 and were unchanged. Leaf area, dry mass, and tiller development increased in +CO₂ plants and decreased in -CO₂ plants. In the interval between 8 and 22 DAT, lower net assimilation rate in +CO₂ than in -CO₂ plants was observed.     

Genotype Variability in Photosynthetic Characteristics in Finger Millet

High variability in leaf gas exchange and related traits were found in 30 genotypes of field grown finger millet. The variability in carbon exchange rate per unit leaf area (P _N) can be partly attributed to the differences in the stomatal conductance (g_s) and area leaf mass (ALM). The P _N was positively correlated with total dry matter (TDM). However, no relationship between P _N and seed yield was found. The leaf area showed a positive and significant correlation with total biomass. None of the other gas-exchange traits had significant relationship either with TDM or with seed yield. The ALM showed a strong positive association with P _N. However, it was not correlated with either total biomass or seed yield. As a result, the use of ALM as surrogate for P _N for identifying high biomass producing genotypes only had a limited value. Hence selection for high P _N would result in higher biomass producing types.     

Measurements of gross and net ecosystem productivity and water vapour exchange of a Pinus ponderosa ecosystem,and an evaluation of two generalized models

Net ecosystem productivity (NEP), net primary productivity (NPP), and water vapour exchange of a mature Pinus ponderosa forest (44°30′ N, 121°37′ W) growing in a region subject to summer drought were investigated along with canopy assimilation and respiratory fluxes. This paper describes seasonal and annual variation in these factors, and the evaluation of two generalized models of carbon and water balance (PnET‐II and 3‐PG) with a combination of traditional measurements of NPP, respiration and water stress, and eddy covariance measurements of above‐and below‐canopy CO₂ and water vapour exchange. The objective was to evaluate the models using two years of traditional and eddy covariance measurements, and to use the models to help interpret the relative importance of processes controlling carbon and water vapour exchange in a water‐limited pine ecosystem throughout the year. PnET‐II is a monthly time‐step model that is driven by nitrogen availability through foliar N concentration, and 3‐PG is a monthly time‐step quantum‐efficiency model constrained by extreme temperatures, drought, and vapour pressure deficits. Both models require few parameters and have the potential to be applied at the watershed to regional scale. There was 2/3 less rainfall in 1997 than in 1996, providing a challenge to modelling the water balance, and consequently the carbon balance, when driving the models with the two years of climate data, sequentially. Soil fertility was not a key factor in modelling processes at this site because other environmental factors limited photosynthesis and restricted projected leaf area index to ～1.6. Seasonally, GEP and LE were overestimated in early summer and underestimated through the rest of the year. The model predictions of annual GEP, NEP and water vapour exchange were within 1–39% of flux measurements, with greater disparity in 1997 because soil water never fully recharged. The results suggest that generalized models can provide insights to constraints on productivity on an annual basis, using a minimum of site data.