Genetic variation of physiological response to aflatoxin in Gallus domesticus

Summary A pedigreed, commercial broiler population of 31 sire families was administered dietary aflatoxin at levels of either 0.0 or 5.0 g of aflatoxin per g of diet from 7 to 21 days of age and their response assessed by various physiological parameters.Body weight, gain, packed red blood cell volume (PCV). plasma albumin, plasma protein and cholesterol responses were significantly reduced from control values by the 5.0 g/g aflatoxin diet. Males had greater body weights and gains in both dietary regimes than females. Females had significantly higher PCV, protein, albumin and cholesterol values in the 5.0 g/g aflatoxin group than their male counterparts. These differences resulted in significant sex × aflatoxin level interactions for these parameters. Coefficients of variation were increased for all parameters measured in the 5.0 g/g aflatoxin treatment compared to values for the control group. This increase was greatest for plasma protein, albumin, and cholesterol responses. Heritabilities were calculated for all responses within both treatment groups and were found to be increased in all cases by the 5.0 g/g aflatoxin diet. Highly significant phenotypic correlations were determined between body weight and gain and between plasma albumin and total plasma protein in both treatment groups. High phenotypic correlations among PCV, plasma cholesterol, plasma protein, and plasma albumin were noted in the 5.0 g/g aflatoxin group. Significant genetic correlations were determined between body weight and gain and between plasma albumin and plasma protein in the control group. Body weight and gain and plasma protein, albumin, cholesterol and PCV were genetically correlated in the 5.0 g/g aflatoxin group. Genetic correlations calculated across environments for the same traits were high for PCV, body weight and gain and much lower for plasma albumin, plasma protein, and plasma cholesterol.The results of this study demonstrate that genetic variability for resistance to aflatoxin exists in commercial broiler populations. Strong genetic and phenotypic relationships, and high heritabilities associated with plasma albumin and protein suggest their applicability as selection criteria for aflatoxin resistance. Genetic correlation for these traits across dietary environments indicate that responses for aflatoxin resistance should be measured during aflatoxin challenge and suggest that selection for growth and selection for aflatoxin resistance are not antagonistic.     

Alfalfa,Medicago sativa L., in highly weathered,acid soils

Summary Seedlings of a broad based population of alfalfa, (Medicago sativa L.), were visually selected for 2 generations (cycles) in an acid Cecil soil (pH=4.8). Simultaneously, 2 generations of selections were made in a limed Cecil soil (pH=6.2) amended with phosphorus. When tested in acid soil (pH=4.8) with added P, the cycle 2 acid selections yielded significantly more top yield than either the limed selections or the original seed. When grown in the limed soil (pH=6.2) without added P, the acid selections yielded significantly less. There were no significant differences among selections in other soil conditions (pH=4.8, no P added and pH=6.2, P added). Root weight and length and nodule fresh weight correlated well with top yield in all treatments. The yield of the 10 parent varieties and polycrossed seed of their cycle 1 acid and cycle 1 limed selections were compared under two soil conditions (acid and limed). The results of this test indicate that some varieties were more responsive to acid soil selection than other. Overall, none of the 10 varieties showed any decreases in total top yield due to one cycle of selection in either the acid or limed soil conditions.     

A ganglioside receptor on lymphocytes mediates recognition of self

Lymphocytes from mouse spleen and thymus form spontaneous rosettes with autologous erythrocytes. Certain gangliosides are described here as potent inhibitors of this cell contact formation. A comparison of several gangliosides shows that lymphocytes from thymus and spleen differ significantly in their reactivity towards GM1, GM3, GD1a, GD1b and GT1b. Differences are also seen between inbred mouse strains.     

Hormonal monitoring of age at sexual maturation in female Goeldi's monkeys (Callimico goeldii) in their family groups

The aim of this study was to determine whether or not sexual maturation is attained in the family group in captive‐born Goeldi's monkey (Callimico goeldii) and if so, at what age and body weight. To monitor ovarian activity in 14 female Goeldi's monkeys, urinary content of pregnanediol‐3α‐glucuronide (PdG) was determined using radioimmunoassay. Urinary samples were collected between the ages of 6 and 70 weeks. Subjects became sexually mature while still housed in their family groups, at a median age of 57 weeks (48–< 70 weeks). Median body weight at the age of sexual maturity was 473 g (N = 10; 420–543 g). This corresponded to 90% of the median non‐pregnant body weight of breeding females in our colony (526 g, N = 8). Therefore, Goeldi's monkey is similar to Leontopithecus but different from Cebuella, Callithrix, and Saguinus, in terms of daughters ovulating in the family group and at a relatively young age. Am. J. Primatol. 48:77–83, 1999. © 1999 Wiley‐Liss, Inc.     

橘小实蝇和番石榴实蝇幼虫之间的竞争机制

为了明确橘小实蝇Bactrocera dorsalis (Hendel)和番石榴实蝇Bactrocera correcta (Bezzi)资源利用的种间竞争机制,比较两者的竞争实力,本文研究了两种实蝇幼虫在26℃条件下于人工饲料和番石榴中的种间竞争关系。结果显示,两种实蝇同龄幼虫在共同饲养的竞争条件下,橘小实蝇幼虫期缩短、存活率提高,而番石榴实蝇蛹重变轻、存活率降低,橘小实蝇通过加快自身生长和抑制番石榴实蝇生长的方式在资源利用竞争中获得更多资源。因此,两种实蝇幼虫在种间竞争中,橘小实蝇可通过调整生活史对策获得竞争优势。     

饲养瓢虫的替代食物:利用地中海粉螟卵与油菜花粉连续多代饲喂稻红瓢虫

稻红瓢虫Micraspis discolor(Fabricius)是稻田害虫捕食性天敌优势种之一,捕食包括蓟马、稻蚜、叶蝉、飞虱Delphacidae、鳞翅目幼虫和卵等多种水稻害虫,对褐飞虱Nilaparvata lugens有控制作用.为了筛选出稻红瓢虫系统化饲养适宜的替代食物,本研究利用地中海粉螟Ephestia ...     

Phosphorus supply and arbuscular mycorrhizas increase growth and net gas exchange responses of two Citrus spp. grown at elevated [CO2]

We hypothesized that greater photosynthate supply at elevated [CO₂] could compensate for increased below-ground C demands of arbuscular mycorrhizas. Therefore, we investigated plant growth, mineral nutrition, starch, and net gas exchange responses of two Citrus spp. to phosphorus (P) nutrition and mycorrhizas at elevated atmospheric [CO₂]. Half of the seedlings of sour orange (C. aurantium L.) and ‘Ridge Pineapple’ sweet orange (C. sinensis L. Osbeck) were inoculated with the arbuscular mycorrhizal (AM) fungus, Glomus intraradices Schenck and Smith and half were non-mycorrhizal (NM). Plants were grown at ambient or 2X ambient [CO₂] in unshaded greenhouses for 11 weeks and fertilized daily with nutrient solution either without added P or with 2 mM P in a low-P soil. High P supply reduced AM colonization whereas elevated [CO₂] counteracted the depressive effect of P on intraradical colonization and vesicle development. Seedlings grown at either elevated [CO₂], high P or with G. intraradices had greater growth, net assimilation of CO₂ (A _CO2) in leaves, leaf water-use efficiency, leaf dry wt/area, leaf starch and carbon/nitrogen (C/N) ratio. Root/whole plant dry wt ratio was decreased by elevated [CO₂], P, and AM colonization. Mycorrhizal seedlings had higher leaf-P status but lower leaf N and K concentrations than nonmycorrhizal seedlings which was due to growth dilution effects. Starch in fibrous roots was increased by elevated [CO₂] but reduced by G. intraradices, especially at low-P supply. In fibrous roots, elevated [CO₂] had no effect on C/N, but AM colonization decreased C/N in both Citrus spp. grown at low-P supply. Overall, there were no species differences in growth or A _CO2. Mycorrhizas did not increase plant growth at ambient [CO₂]. At elevated [CO₂], however, mycorrhizas stimulated growth at both P levels in sour orange, the more mycorrhiza-dependent species, but only at low-P in sweet orange, the less dependent species. At low-P and elevated [CO₂], colonization by the AM fungus increased A _CO2 in both species but more so in sour orange than in sweet orange. Leaf P and root N concentrations were increased more and root starch level was decreased less by AM in sour orange than in sweet orange. Thus, the additional [CO₂] availability to mycorrhizal plants increased CO₂ assimilation, growth and nutrient uptake over that of NM plants especially in sour orange under P limitation. This revised version was published online in June 2006 with corrections to the Cover Date.     

Localization of Heat Shock Protein of Low Molecular Weight by Electromicroscopic Immunogold-Labelling

Inspire of the large amount of low molecular weight heat shock protein (LMW HSP) present in plant, its function has still not been clearly known. Understanding the distribution and movement of LMW HSP in cells could provide useful information about its biological functions. A 14 kD HSP was purified from the microsome isolated from the bean of a highly thermotolerant plant Phaseolus vulgaris. Antiserum against this protein was preparaed. The localization of the protein in the cell was analysed by means of electromicroscopic immunogold-labelling method. The images of electromicrograph showed that 14 kD HSP mainly existed in both cytoplasm and endoplasmic reticulum and that no labeled gold was found in tonoplasma, mitochondria or cell wall.     

京津地区大仓鼠种群年龄结构的研究

大仓鼠(Cricetulus triton)主要分布于我国季风温带的一些地区,为京津及华北地区农田的主要害鼠之一。以往虽有一些报道(刘焕金,1982;寿振黄,1962;B-,1952),但对种群生态的系统研究报道尚未见到。 种群年龄结构中各年龄组的比例,是研究种群繁殖、分析种群数量发展和变化的基础,是种群生态研究中首先要搞清楚的问题。     

Bacterial leaching of two Swedish zinc sulfide ores

Abstract: Two Swedish zinc sulfide ores, from Saxberget (S-ore) and Kristineberg (K-ore), respectively, were compared for bacterial leachability with respect to grain size, and additions of ammonia, iron and phosphate. 87 days of column leaching resulted in 2.4–3.2 g Zn/I in solution and 1.5–1.9 g Cu/I from the K-ore and 1.2–5.3 g Zn/l and 0–0.3 g Cu/l from the S-ore. The highest values were achieved for grain sizes between 16 and 64 mm. Ammonium showed a stimulating effect on bacterial leaching, increasing leached Zn in the K-ore from 27% to 35% and from 7% up to 70% Zn in the S-ore after 53 days of batch leaching. Phosphate additions showed negative effects. Iron additions had a positive effect for the K-ore, increasing the leaching from 48% to 78% Zn at an addition of 6 mg Fe²⁺.