Genetically determined sex-reversal in 46,XY humans

Evidence is presented for the existence of a gene, probably on the X chromosome, which prevents testis differentiation when present in 46,XY human embryos. Affected 46,XY women are not completely normal because of premature ovarian involution, as a result of which they have "streak gonads" similiar to those of 45,X women.     

Contribution of gular pumping to lung ventilation in monitor lizards

A controversial hypothesis has proposed that lizards are subject to a speed-dependent axial constraint that prevents effective lung ventilation during moderate- and high-speed locomotion. This hypothesis has been challenged by results demonstrating that monitor lizards (genus Varanus) experience no axial constraint. Evidence presented here shows that, during locomotion, varanids use a positive pressure gular pump to assist lung ventilation. Disabling the gular pump reveals that the axial constraint is present in varanids but it is masked by gular pumping under normal conditions. These findings support the prediction that the axial constraint may be found in other tetrapods that breathe by costal aspiration and locomote with a lateral undulatory gait.     

玉米矮花叶病毒源鉴定和受侵叶片的超微结构

利用生物接种、血清学反应和电子显微镜观察等方法,对大田发生的玉米矮花叶病毒源进行了鉴定。利用超薄切片系统研究了玉米受MDMV侵染后超微结构的变化。在细胞质中观察到风轮状、卷叶状、束状、圆柱状内含体和简单的囊泡到高度卷曲的膜系统。受侵细胞产生两种不同类型的胞间连丝,a型为正常胞间连丝,b型的胞间连丝伸出指状突起,这可能是细胞限制病毒在寄主体内运转的一种结构。壁旁体的出现与寄主细胞壁加厚及封闭胞间连丝有关。     

Juvenile hormone induced vitellogenin synthesis in the monarch butterfly

The vitellogenin (yolk protein) of the monarch butterfly has been identified by electrophoretic and immunochemical techniques. In freshly emerged female adults ligature of the neck prevents appearance of this protein in the hemolymph; it prevents yolk deposition and egg maturation as well. These processes are restored by injection of juvenile hormone; the restoration involves induction of vitellogenin synthesis, as shown by incorporation of [(3)H]leucine.     

Role of the kinase MST2 in suppression of apoptosis by the proto-oncogene product Raf-1

The ablation of the protein kinase Raf-1 renders cells hypersensitive to apoptosis despite normal regulation of extracellular signal-regulated kinases, which suggests that apoptosis protection is mediated by a distinct pathway. We used proteomic analysis of Raf-1 signaling complexes to show that Raf-1 counteracts apoptosis by suppressing the activation of mammalian sterile 20-like kinase (MST2). Raf-1 prevents dimerization and phosphorylation of the activation loop of MST2 independently of its protein kinase activity. Depletion of MST2 from Raf-1-/- mouse or human cells abrogated sensitivity to apoptosis, whereas overexpression of MST2 induced apoptosis. Conversely, depletion of Raf-1 from Raf-1+/+ mouse or human cells led to MST2 activation and apoptosis. The concomitant depletion of both Raf-1 and MST2 prevented apoptosis.     

Mechanism of spontaneous cure in puberty of ringworm of the scalp

With onset of puberty, the sebaceous glands of the scalp start to secrete a sebum which contains, in higher concentration than before, lowboiling saturated fatty acids with selective fungistatic and fungicidal action on M. audouini. Highly active normal aliphatic monobasic acids having odd numbers of carbon atoms, including pelargonic acid, have been isolated from hair fat of adults. The "adult type" of hair fat does not kill the fungus spores within the hair but prevents infection of the new hair following the old infected hair in the process of shedding. Detailed reports are to be published elsewhere.     

作物耐旱基因的表达特性及遗传工程研究

干旱会限制作物生长及产量形成,并引起作物体内一系列生理生化反应。作物耐旱性是多基因控制的复杂数量性状,为了应对水分缺失,作物体内形成多条信号途径,并在形态、生理和分子水平上适应干旱。受到干旱胁迫后,作物通过激活相关转录因子来调控相应下游基因的表达,并且通过转录后调控和渗透调节来适应干旱,维持正常的生理活动和代谢活动,减少干旱胁迫对植物的伤害。逆境也会诱导小RNA的产生,其通过诱导目的基因mRNA的降解以及阻止翻译过程去调控靶基因,达到耐胁迫逆境的作用。耐旱相关基因的遗传工程对作物在非生物逆境下的正常生长非常重要,总结了干旱响应机制所涉及的基因的功能及利用情况,以期为耐旱育种提供参考依据。     

Tricyclic antidepressants: evidence for an intraneuronal site of action

Desipramine, a tricyclic antidepressant drug, almost completely prevents the accumulation of tritiated norepinephrine by sympathetic neurons of the rat heart after the injection of a tracer dose of the labeled amine. However, desipramine does not alter the accumulation of norepinephrine after the injection of a large dose of the neurohormone. Despite the failure of desipramine to block the neuronal uptake of norepinephrine, it still prevents exogenous norepinephrine from displacing the endogenous neurohormone (previously labeled with H(3)-norepinephrine) from intraneuronal storage sites.     

An apical-membrane chloride channel in human tracheal epithelium

The mechanism of chloride transport by airway epithelia has been of substantial interest because airway and sweat gland-duct epithelia are chloride-impermeable in cystic fibrosis. The decreased chloride permeability prevents normal secretion by the airway epithelium, thereby interfering with mucociliary clearance and contributing to the morbidity and mortality of the disease. Because chloride secretion depends on and is regulated by chloride conductance in the apical cell membrane, the patch-clamp technique was used to directly examine single-channel currents in primary cultures of human tracheal epithelium. The cells contained an anion-selective channel that was not strongly voltage-gated or regulated by calcium in cell-free patches. The channel was also blocked by analogs of carboxylic acid that decrease apical chloride conductance in intact epithelia. When attached to the cell, the channel was activated by isoproterenol, although the channel was also observed to open spontaneously. However, in some cases, the channel was only observed after the patch was excised from the cell. These results suggest that this channel is responsible for the apical chloride conductance in airway epithelia.     

兔巴氏杆菌大肠杆菌油乳灭活苗的制备及效果测定

以多杀性巴氏杆菌(C-481)、致病性大肠杆菌O85、O119、O18等菌株制备的兔巴氏杆菌 大肠杆菌油乳灭活菌苗，经实验室免疫实验和中间实验表明，该菌苗在免疫后第14天即可产生坚强的免疫力；攻毒实验表明。该菌苗的保护率为93％，免疫期为9个月。免疫效果普遍反应良好。该菌苗在4℃可保存18个月以上。室温阴暗处可保存10个月以上。临床证明该菌苗能有效地控制巴氏杆菌与大肠杆菌在兔群中的流行。可进行推广应用。     

稻水象甲物理防治新技术试验研究

利用物理方法防治稻水象甲,可有效降低对环境的危害,提高质量。灯光诱杀和防虫网及覆膜在防治稻水象甲上有很好的防治效果。同时,可提高作物抗性,经济效益、社会效益、生态效益显著。     

Granulosa cell ligand NPPC and its receptor NPR2 maintain meiotic arrest in mouse oocytes

Granulosa cells of mammalian Graafian follicles maintain oocytes in meiotic arrest, which prevents their precocious maturation. We show that mouse mural granulosa cells, which line the follicle wall, express natriuretic peptide precursor type C (Nppc) messenger RNA (mRNA), whereas cumulus cells surrounding oocytes express mRNA of the NPPC receptor NPR2, a guanylyl cyclase. NPPC increased cGMP levels in cumulus cells and oocytes and inhibited meiotic resumption in vitro. Meiotic arrest was not sustained in most Graafian follicles of Nppc or Npr2 mutant mice, and meiosis resumed precociously. Oocyte-derived paracrine factors promoted cumulus cell expression of Npr2 mRNA. Therefore, the granulosa cell ligand NPPC and its receptor NPR2 in cumulus cells prevent precocious meiotic maturation, which is critical for maturation and ovulation synchrony and for normal female fertility.     

Ascorbic Acid as a factor controlling the development of cyanide-insensitive respiration

Lycorine, an inhibitor of ascorbic acid biosynthesis, prevents the elicitation of KCN-insensitive respiration in aerated potato tuber slices. Ascorbic acid administration prevents the lycorine effect. Because KCN-insensitive respiration, which takes place during the aerobic incubation of potato tuber slices, specifically depends on the synthesis of new proteins, we suggest that ascorbic acid could be required to carry out a synthetic process.     

山羊腔前卵泡卵母细胞体外发育的超微结构研究

电镜研究表明,山羊腔前卵泡卵母细胞体外培养７ｄ时,其超微结构基本与发育速度一致。在培养后期（１６ｄ）,卵母细胞的超微结构表现了不同的发育阶段,试验中观察到ＧＶＢＤ期,核膜开始部分消失的现象,并记录到１枚成熟卵子老化后的结构特征。但大多数卵母细胞培养结束时,未观察到ＣＧｓ质膜下的排列现象,有的卵母细胞线粒体仍为椭园形,板状嵴,细胞器迁移不完全正常。推测该时期有的卵母细胞部分代谢机能失调,从而导致某些合成（如ＣＧｓ）障碍或某些细胞器的迁移发生障碍。因此,培养后期可能是影响卵母细胞成熟的关键时期。     

SNARE proteins: one to fuse and three to keep the nascent fusion pore open

Neurotransmitters are released through nascent fusion pores, which ordinarily dilate after bilayer fusion, preventing consistent biochemical studies. We used lipid bilayer nanodiscs as fusion partners; their rigid protein framework prevents dilation and reveals properties of the fusion pore induced by SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor). We found that although only one SNARE per nanodisc is required for maximum rates of bilayer fusion, efficient release of content on the physiologically relevant time scale of synaptic transmission apparently requires three or more SNARE complexes (SNAREpins) and the native transmembrane domain of vesicle-associated membrane protein 2 (VAMP2). We suggest that several SNAREpins simultaneously zippering their SNARE transmembrane helices within the freshly fused bilayers provide a radial force that prevents the nascent pore from resealing during synchronous neurotransmitter release.     

Histamine augments leukocyte adenosine 3',5'-monophosphate and blocks antigenic histamine release

Extracellular histamine stimulates accumulation of adenosine 3',5'-monophosphate in human leukocytes and prevents antigenic release of histamine from cells of allergic donors. Both effects occur at histamine concentrations that can be achieved by antigenic release of the amine in vitro.     

Chemically induced porphyria: prevention by prior treatment with phenobarbital

The excessive induction of hepatic delta-aminolevulinic acid synthetase in rats after the administration of porphyria-inducing compounds is prevented by prior treatment with phenobarbital. Studies in vivo and in vitro indicate that phenobarbital prevents the induction of chemical porphyria by increasing the rate of detoxification of inducers by way of drug-metabolizing enzymes of the hepatic endoplasmic reticulum.     

一串红茎腐病的发生及防治

不少养花爱好者缺乏防治一串红茎腐病的经验,本文着重介绍了一串红茎腐病的正确识别、发病规律及防治经验,以供养花爱好者参考。     

Corticosterone regulation of tryptophan hydroxylase in midbrain of the rat

The tryptophan hydroxylase activity in the rat midbrain decreases after adrenalectomy and is restored by treatment with corticosterone. Cycloheximide, adminiistered intracisternally, prevents the restoration of the enzyme activity by corticosterone. Cycloheximide administration to adrenalectomized rats resutlts in a further decrease in the enzyme activity. an indication that the enzyme has a rapid turnover even in the absence of corticosterone.     

农作物秸秆的综合利用研究

以小麦秸秆焚烧对小麦幼苗的影响为例,从理论上证明了焚烧秸秆的危害,指出秸秆的综合利用既创造了一定的经济价值和社会效益,又避免了露天燃烧等引起的环境污染和资源浪费问题。