Identification of isopeptide bonds in heat-treated wheat gluten peptides

Results in this paper confirm heat-induced isopeptide bond formation in wheat gluten. Heating (24 h, 130 °C) of wheat gluten [moisture content 7.4%] decreased its extractability in sodium dodecyl sulfate containing buffer (pH 6.8), even after reduction of disulfide (SS) bonds. Thus, both SS bonds and non-SS bonds were responsible for the extractability loss. Cross-links of the lysinoalanine and lanthionine type were not present in the heated samples, but heat treatment reduced levels of available amino groups. Heating of purified and alkylated high molecular weight glutenin subunits (HMW-GS) under similar conditions also resulted in extractability loss, demonstrating that cross-linking did not solely depend on the availability of cysteine or cystine. These observations indicated that heat treatment had induced isopeptide bond formation, resulting in larger and unextractable molecules. Heating HMW-GS lysine- and glutamine-containing peptides induced the formation of isopeptide bonds, thereby supporting the above hypothesis. The level of isopeptide bond formation increased with heating time.     

Resting metabolic rates increase with elevation in a mountain‐dwelling lizard

Individuals that inhabit broad elevational ranges may experience unique environmental challenges. Because temperature decreases with increased elevation, the ectotherms living at high elevations have to manage limited activity time and high thermoregulatory effort. The resting metabolic rate (RMR) of a postabsorptive animal is related to its total energy requirements as well as many other fitness traits. Mesquite lizards (Sceloporus grammicus) living on La Malinche Volcano, Mexico, inhabit a wide elevational range with some populations apparently thriving above the tree line. We measured the RMR of lizards from different elevations (i.e., 2,600, 3,200, and 4,100 m) at four ecologically relevant temperatures (i.e., 15, 25, 30, and 35 °C) and found that RMR of mesquite lizards increased with temperature and body mass. More importantly, lizards from the high‐elevation population had mass specific RMR that was higher at all temperatures. While the higher RMRs of high‐elevation populations imply higher metabolic costs at a given temperature these lizards were also smaller. Both of these traits may allow these high elevation populations to thrive in the face of the thermal challenges imposed by their environment.     

Fractionation of cereal flour by sedimentation in non-aqueous systems. II. Rheological characterisation and baking performance of the protein fraction

A previously described method for the non-aqueous fractionation of cereal flours by sedimentation in non-aqueous solvents was carried out using flours of three wheat cultivars differing in baking performance, as well as one rye and one barley flour. The method was based on differences in the densities of starch (higher) and protein (lower). Thus, suspending finely milled flour in an inert solvent mixture with a density in between the densities of starch and protein yielded a sedimented starch fraction and a protein-rich fraction at the surface of the solvent. Further purification of this upper fraction provided a protein fraction, a middle fraction, and a lipid fraction. The protein fractions were examined by means of rheological methods such as micro-extension tests and creep-recovery tests. They also were reconstituted to standard flour with a protein content of 13.5%, which was used for micro-scale baking tests. Compared to aqueous isolated gluten, the hydrated protein fractions from wheat were much more extensible and had a lower resistance to extension. The baking performance of the wheat protein fractions was superior to gluten and comparable to the native wheat flours. The protein fraction from rye gave a wheat-like bread crumb, whereas the barley protein was not suited for bread making.     

华南乡土树种在松杉林下生长及林下植物多样性研究

研究了11种华南乡土阔叶树种幼树在广东增城市林科所松杉人工林林下的生长表现,结果表明:4种壳斗科植物黎蒴、米锥、甜锥和槟榔青冈在移植后5 a均具有较高的树高和冠幅生长量,可作为人工林改造优良树种;香椿在前期生长表现良好,而移植后45 a生长速度有所下降,反映该树种随着年龄增长,其需光性加强,该树种仅适用于低密度人工林的改造;石笔木生长虽然稍慢,但其耐荫性较强,在林下生长良好,可作为次生林改造树种;樟树、枫香和火力楠等树种在林下生长不良.样方调查结果表明:松杉林下植物以耐荫性和鸟播植物为主.     

中国美利奴羊育种信息管理系统开发

以提高育种资料管理和利用效率为目的,提出基于Visual FoxPro6.0软件开发中国美利奴羊育种信息管理系统的设计思路,阐述了系统的结构和所具备的基本功能.     

Influence of Portland cement amendment on soil pH and residual soil termiticide performance

Soil adjacent to new brick veneer work is likely to have a higher pH owing to the mixture of cement with the soil. In the Gainesville, FL, area, soil samples taken from such locations had a range of pH values from 9.0 to 10.1; similar soils used in bioassays had a pH of 5.6 before the addition of cement. Addition of 15 mg of Portland cement to 33 g of soil increased the pH to 6, and addition of 291 mg of Portland cement increased the pH to 9. The pH of soil amended with cement was stable for the first 5 months. After 10 months, soil pH values decreased from alkaline to near neutral in all cases. Eastern subterranean termite workers, Reticulitermes flavipes (Kollar), were exposed to the treated soil at pH 6-9 for 24 h, and percentage mortality was recorded at 5 days, 5 months and 10 months. Termite mortality significantly decreased at higher soil pHs for bifenthrin, chlorpyrifos, fipronil and imidacloprid treatments at 5 months and similarly for bifenthrin, permethrin, chlorpyrifos, fipronil and imidacloprid treatments at 10 months. There was an inverse linear relationship between soil pH and mortality. Increased soil pH diminished residual activity of termiticide in the following order: imidacloprid > fipronil > chlorpyrifos = bifenthrin > permethrin > cypermethrin.     

Regional distribution and integrity of equine ovarian pre‐antral follicles

The goal of this study was to determine the distribution of pre‐antral follicles in the ovarian parenchyma of mares. For Experiment 1, each ovary was cut longitudinally at the greater curvature, performing two hemiovaries. After that, six fragments from each hemiovary were obtained, resulting in 12 fragments, which were divided into the innermost region of the parenchyma, the middle region and the outermost region. All the three obtained sections were cut transversally to obtain two fragments from each one. For Experiment 2, each ovary also submitted to a longitudinal cut on the greater curvature, forming two hemiovaries. Each hemiovary was sectioned into four symmetrical fragments, resulting in eight fragments per ovary. The fragments were related as being near to or far from the ovulatory fossa. The fragments of both experiments were immediately fixed in Carnoy for 12 hr and kept in 70% ethanol for 24 hr. Follicles were classified according to the stages of development and for morphological integrity according to oocyte morphology and granulosa cells. After the histological assessment, a total of 1,130 follicles were visualized from Experiment 1, being 1,054 (93.3%) primordial follicles and 76 (4.7%) follicles in development. The innermost region had the highest percentage of pre‐antral follicles compared to the other regions (p < .05). The middle and outermost regions showed higher percentages of intact primordial and developing follicles than the innermost region (p < .05). Considering Experiment 2, 938 follicles were found, being 894 (95.3%) primordial and 44 (4.7%) follicles in development. The region near the ovulatory fossa presented higher (58.7%; 551 of 938) follicular concentration compared to the region far from the ovulatory fossa (41.3%; 387 of 938; p < .05). As a conclusion, distribution of pre‐antral follicles in the equine ovary has a specific pattern through the parenchyma. Also, the follicular integrity differed in the studied ovarian areas.     

不同处理方法对美国截叶胡枝子种子发芽的影响

截叶胡枝子(Lespedezacunecta)是原产于亚洲东部的一种多年生的豆科植物,在我国南方地区野生分布很广。它具有耐瘠、耐旱、耐酸、耐热、固土能力强、适应性广等特性,在国外也颇受重视。我国于1983年从美国引种,通过对其生物学和生态学特性、经济性状和栽培技术研究证明,引进的美国截叶胡枝子在人工栽培条件下,表现出良好的经济性状,是南方草地改良的希望种子。但是在生产中,由于其硬实的存在,使得种子的发芽率很低,往往造成出苗困难和草地建植缓慢,甚至出现严重缺苗断垄的现象,直接影响田间产量,限制了它的进一步推广应用。试验采用不同处…     

高温胁迫对岷江百合幼苗耐热指数和理化特性的影响

为了探明岷江百合幼苗在高温胁迫下的生理反应,以离体扩繁的岷江百合幼苗为研究材料,对其进行了不同高温(37℃/30℃、42℃/37℃)和不同时间(0、4、8、16、32、48 h)处理,研究了高温胁迫对其耐热指数和有关生理生化指标(叶绿素、丙二醛、游离脯氨酸、可溶性蛋白含量和SOD活性)的影响.结果表明:随着温度的升高和处理时间的延长,植株的耐热指数不断下降,叶绿素含量减少,丙二醛(MDA)含量增加;42℃胁迫32 h后,游离脯氨酸、可溶性蛋白含量、SOD活性均达到最大值,分别比对照增加了0.66倍、1.77倍和9.78倍.但胁迫48 h后,指标显著下降,这说明,42℃间断胁迫48 h对植株产生了不可逆的的热伤害作用.