Effects of selenium source and level on growth performance,antioxidative ability and meat quality of broilers

This experiment was conducted to investigate the effects of selenium(Se) source and level on growth performance, carcass traits, antioxidative ability and meat quality of broilers. A total of 320 one-d-old Arbor Acres commercial broilers were randomly assigned to 1 of 5 treatments with 8 replicates in a completely randomized design involving a 2×2 factorial arrangement of treatments plus one Se-unsupplemented basal diet control for 42 d. The two Se sources were sodium selenite and Se yeast, and the two supplemental Se levels were 0.20 and 0.40 mg Se kg–1. The results showed that broilers fed the Se-supplemented diets had higher(P0.05) average daily gain and average daily feed intake from 22 to 42 d of age, eviscerated yield and abdominal fat percentages, Se concentrations and glutathione peroxidase(GSH-Px) activities in breast and thigh muscles on d 42, and lower(P0.05) feed/gain from 1 to 21 and 22 to 42 d of age, mortality from 22 to 42 d of age and malondialdehyde(MDA) concentration in thigh muscle on d 42 than those fed the control diet. Broilers fed the diets supplemented with Se yeast had higher(P0.05) p H value and lower(P0.05) shear force in thigh muscle than those fed the diets supplemented with sodium selenite. Additionally, broilers fed the diets supplemented with 0.40 mg Se kg–1 had lower(P0.05) shear force in thigh muscle and higher(P0.05) GSH-Px activities in breast and thigh muscles than those fed the diets supplemented with 0.20 mg Se kg–1. Furthermore, broilers fed the diet supplemented with Se yeast at 0.40 mg Se kg–1 had higher(P0.05) Se concentrations in breast and thigh muscles than those fed the diet supplemented with Se yeast at 0.20 mg Se kg–1, but no differences(P0.05) were observed in these indices of broilers fed the diets supplemented with sodium selenite between 0.20 and 0.40 mg Se kg–1. The results from the present study indicated that supplemental Se could increase the growth performance, muscle Se concentration and antioxidative ability of broilers; and the Se from Se yeast was more effective than the Se from sodium selenite in improving meat quality of broilers.     

Chemostimulatory protein: a new type of taste stimulus

Three taste-active proteins have recently been discovered. It is proposed that two of these (monellin and thaumatin) should be classified as chemostimulatory proteins because of their sensory effect; these two proteins taste intensely sweet. The third protein (miraculin), a taste-modifier protein, changes the normal sour taste of acids to sweet. The taste-modifier protein, miraculin, occurs in the fruit of the tropical plant Synsepalum dulcificum. Though itself not sweet, it is able to change the taste of acids from sour to sweet after the tongue has been treated with the protein. Miraculin is a basic glycoprotein with a molecular weight of 44,000. Monellin, a chemostimulatory protein, is found in the fruit of a different tropical plant, Dioscoreophyllum cumminsii. It has been characterized as a basic protein with a molecular weight of 10,700 that contains no carbohydrate. Thaumatin, another chemostimulatory protein, occurs in the fruit of a third tropical plant, Thaumatococcus daniellii. Like monellin, it is a basic protein that contains no carbohydrate. Its molecular weight is around 21,000. Certain gross similarities among the three proteins have been noted. Their basic ionic character and some features of the amino acid compositions are similar. Little is known of the structural features of the chemostimulatory proteins that are required for eliciting their intense sweetness; they are of the order of 10(5) times more effective than sucrose. The precise role of the tertiary structure in their biological activity is not known but appears to be an important area for further study. The relatively large size (11,000 to 21,000 molecular weight) of the chemostimulatory proteins provides indirect evidence that the initial interaction of these stimuli with taste receptor cells occurs at the plasma membrane.     

Fossilized eggs in a pennsylvanian blastoid

A single specimen of Pentremites rusticus (Echinodermata, Blastoidea) from the Early Pennsylvanian of Oklahoma has hundreds of apparent eggs in one of its abnormal anal hydrospire groups. This rare occurrence suggests that female blastoids in this sexually dimorphic species had modified their anal hydrospiresfor brooding eggs instead of for normal respiration.     

Hydraulic transients: a seismic source in volcanoes and glaciers

A source for certain low-frequency seismic waves is postulated in terms of the water hammer effect. The time-dependent displacement of a water-filled sub-glacial conduit is analyzed to demonstrate the nature of the source. Preliminary energy calculations and the observation of hydraulically generated seismic radiation from a dam indicate the plausibility of the proposed source.     

Water salination: a source of energy

The thermodynamically reversible mixing of freshwater and seawater at constant temperature releases free energy. Salination power as a resource is comparable with hydroelectric power in magnitude; U.S. freshwater runoff could yield over 10(10) watts. The energy flux available for natural salination is equivalent to each river in the world ending at its mouth in a waterfall 225 meters high. An osmotic salination converter could possibly operate at 25 percent efficiency. This energy source is renewable and nonpolluting. Although its full utilization would destroy estuarine environments, it might be practical for specialized purposes.     

Detection of sweet and umami taste in the absence of taste receptor T1r3

The tastes of sugars (sweet) and glutamate (umami) are thought to be detected by T1r receptors expressed in taste cells. Molecular genetics and heterologous expression implicate T1r2 plus T1r3 as a sweet-responsive receptor,and T1r1 plus T1r3,as well as a truncated form of the type 4 metabotropic glutamate receptor (taste-mGluR4),as umami-responsive receptors. Here,we show that mice lacking T1r3 showed no preference for artificial sweeteners and had diminished but not abolished behavioral and nerve responses to sugars and umami compounds. These results indicate that T1r3-independent sweet- and umami-responsive receptors and/or pathways exist in taste cells.     

Influences of dietary sodium on functional taste receptor development: a sensitive period

Restriction of maternal dietary sodium on or before embryonic day 8 reduced taste responses of the chorda tympani nerve to sodium chloride in the offspring. The response attenuation was substantial; responses to sodium chloride in the offspring of deprived rats were approximately 40 percent of those in control animals. Instituting the low sodium diet at embryonic day 10 or later did not produce functional changes. Thus, a sensitive period for the gustatory system exists, and the abrupt transition from maximal environmental susceptibility to no susceptibility occurs during a 2-day prenatal period. Moreover, events important in determining the developmental fate of taste membrane components occur before the initial formation of taste buds.     

Phagocytized platelets: a source of lipids in human thrombi and atherosclerotic plaques

Phagocytosis of lipid-rich platelets by monocytes and the transformation of such cells into lipophages containing fat was observed in human thrombi. The lipophages are similar to lipophages in atherosclerotic plaques. This observation supports the idea that some atherosclerotic plaques are organized mural thrombi.     

Molecular identification of a taste receptor gene for trehalose in Drosophila

The molecular nature of sweet taste receptors has not been fully explored. Employing a differential screening strategy, we identified a taste receptor gene, Tre1, that controls the taste sensitivity to trehalose in Drosophila melanogaster. The Tre1 gene encodes a novel protein with similarity to G protein-coupled seven-transmembrane receptors. Disruption of the Tre1 gene lowered the taste sensitivity to trehalose, whereas sensitivities to other sugars were unaltered. Overexpression of the Tre1 gene restored the taste sensitivity to trehalose in the Tre1 deletion mutant. The Tre1 gene is expressed in taste sensory cells. These results provide direct evidence that Tre1 encodes a putative taste receptor for trehalose in Drosophila.     

DDE: its presence in peregrine eggs in 1948

DDE has been eluted from the dried membranes of peregrine egg-shells collected in California from 1948 to 1950, and identified by gas-liquid chromatography.     

贵州5个代表性绿茶滋味特征与其呈味化合物相关性分析

贵州绿茶品质优异,但目前对其滋味特征的评价仍缺乏数据支撑,介于此,本研究以2020年春季斗茶大赛5个贵州代表性绿茶样品为材料,通过利用人工感官评价、化学分析及智能感官评价,结合化学计量分析、多因子分析等数理分析方法,探究5个代表绿茶的滋味特征与其呈味化合物之间的相关性。人工感官评价结果表明：5个茶样滋味特征略有差异,滋味特征均以醇、爽为主,以GZ1茶样鲜醇较优于其他茶样。化学分析结果表明：5个茶样咖啡碱含量和氨基酸总量均较高,分别在37.43～42.66 mg·g^-1和38.80～70.64 mg·g^-1,茶多酚含量和儿茶素总量均较低,分别在193.47～219.63 mg·g^-1和165.42～187.30 mg·g^-1,茶氨酸、谷氨酸等鲜味氨基酸含量较高。智能感官评价结果表明：电子舌检测5个样品具有较高的鲜味值和丰富度,与感官审评结果“醇、鲜爽”较一致。相关性表明,苦度与咖啡碱、咖啡碱/儿茶素总量有较高的相关性。涩度与表儿茶素没食子酸酯、水浸出物、表没食子儿茶素没食子酸酯/儿茶素总量相关性较高。...     

The ocean: a natural source of carbon monoxide

The surface waters of the western Atlantic are supersaturated with respect to the partial pressure of carbon monoxide in the atmosphere. Under these conditions, the net transport of carbon monoxide across the air-sea interface must be from the sea into the atmosphere. Thus, the ocean appears to act as a source of carbon monoxide. The ocean may be the largest known natural source of this gas, contributing possibly as much as 5 percent of the amount generated by burning of fuels by man.     

大雁卵与鹅卵几种物理性状比较研究

通过对16枚大雁卵和20枚鹅卵的主要物理性状指标的测定、计算,获得它们的蛋形指数、蛋壳厚度以及蛋清、蛋黄和蛋壳在总重量中各自所占比例等指标,经统计分析分别得出了蛋重和蛋黄重,蛋重与蛋壳比例,蛋壳厚度与蛋壳的比例等几对性状之间的相对关系。结果表明,鹅卵重量大于大雁卵,大雁卵蛋壳厚度大于鹅卵,而两者的其他物理性状的变化规律基本一致。     

Gene reactivation in erythrocytes: nuclear transplantation in oocytes and eggs of Rana

Adult erythrocyte nuclei of Rana, transplanted and incubated in the cytoplasm of maturing oocytes, direct matured oocytes to form swimming tadpoles. These results demonstrate that nuclei of noncycling and terminally differentiated erythrocytes contain the genes to specify tadpole development, and conditioning these nuclei in the cytoplasm of oocytes leads to a widespread reactivation of dormant genes.