A role for the sodium pump in photoreception in Limulus

The membranes of photoreceptor cells in Limulus have an electrogenic sodium pump which contributes directly to membrane potential and whose activity is changed by light. These light-induced changes in pump activity underlie the receptor potential.     

Roles of the two Drosophila CRYPTOCHROME structural domains in circadian photoreception

CRYPTOCHROME (CRY) is the primary circadian photoreceptor in Drosophila. We show that CRY binding to TIMELESS (TIM) is light-dependent in flies and irreversibly commits TIM to proteasomal degradation. In contrast, CRY degradation is dependent on continuous light exposure, indicating that the CRY-TIM interaction is transient. A novel cry mutation (cry(m)) reveals that CRY's photolyase homology domain is sufficient for light detection and phototransduction, whereas the carboxyl-terminal domain regulates CRY stability, CRY-TIM interaction, and circadian photosensitivity. This contrasts with the function of Arabidopsis CRY domains and demonstrates that insect and plant cryptochromes use different mechanisms.     

Photoperiodically significant photoreception in sparrows: is the retina involved?

Blind house sparrows (150 birds) and normal ones (199 birds) were subjected to various photoperiodic treatments consisting of cycles of 12 hours light, 12 hours dark and 16 hours light, 8 hours dark at intensities ranging from 20 to 500 lux. The testicular, response of the blind birds was found to be indistinguishable from the response of normal birds under these conditions. The data show that a functional extraretinal photoreceptor exists in this species which is fully capable of mediating the gonadal response to photoperiodic stimuli.     

Nonvisual photic responsiveness in newly hatched pigeons (Columba livia)

Overt behavioral arousal was elicited by light stimulation in pigeon hatchlings. The sensitivity is not mediated via the retina or by direct stimulation of the brain, but rather it is most likely a dermal sensitivity.     

A putative role of the xanthophyll, zeaxanthin, in blue light photoreception of corn coleoptiles

Both flavins and carotenoids have some of the attributes expected for a photoreceptor mediating blue light-induced phototropism in plants. Besides the classical photoreceptor candidate, beta-carotene, coleoptiles contain many other carotenoids, including the main components of the xanthophyll cycle, violaxanthin and zeaxanthin. Here, dark-grown coleoptiles accumulated violaxanthin, but lacked zeaxanthin. Coleoptiles devoid of zeaxanthin did not bend in response to a blue light pulse. Coleoptile tips converted violaxanthin into zeaxanthin in the light. Manipulation of coleoptile zeaxanthin content by red light, red light plus darkness, or incubation with the inhibitor of zeaxanthin formation, dithiothreitol, resulted in a blue light-induced bending that was proportional to zeaxanthin content. These data indicate that zeaxanthin may be a blue light photoreceptor in corn coleoptiles.     

橘小实蝇成虫复眼结构及感光机制

【目的】研究橘小实蝇Bactrocera dorsalis成虫复眼外部形态、内部显微结构和光感受机制。【方法】利用扫描电镜观察橘小实蝇成虫复眼外部形态,组织切片研究成虫复眼内部显微结构及在不同光环境下小眼结构的变化。【结果】橘小实蝇成虫复眼位于头部两侧,正面观呈半球形,表面光滑平坦;小眼间隙有感觉毛,单个小眼由角膜、晶锥、网膜细胞及其特化的视杆、基膜等构成,晶锥、视杆周围和色素细胞内均含有大量的色素颗粒。不同单色光处理后,小眼内的附属色素细胞色素颗粒沿小眼纵轴移动。白光、绿光和黄光处理后,附属色素细胞色素颗粒沿小眼纵轴均匀分布;紫光、蓝光和红光处理后,附属色素细胞色素颗粒主要集中在视网膜细胞远端和角膜的近端。【结论】橘小实蝇雌、雄成虫复眼在外形和内部结构上无差异,均属于并置像眼,屏蔽色素颗粒的移动是其复眼适应外界光环境变化的重要机制,该研究结果为筛选橘小实蝇成虫敏感光波并对其进行灯光诱杀提供了理论依据。     

有髯鸢尾系间远缘杂交障碍研究

有髯鸢尾观赏价值高,但中国夏季雨热集中,有髯鸢尾软腐病多发,限制了有髯鸢尾的应用。为提高有髯鸢尾在高温高湿条件下的存活率,利用鸢尾属内不同系间远缘杂交有望为有髯鸢尾引入鸢尾(Iris tectorum)和西伯利亚鸢尾(Iris sibirica)抗软腐病特性。将有髯鸢尾与鸢尾、西伯利亚鸢尾人工授粉远缘杂交,观察花粉在柱头上萌发及花粉管行为,分析合子前障碍,观测杂交后子房发育动态,明确胚拯救时期。结果表明：1)有髯鸢尾系间远缘杂交存在一定的合子前障碍,表现为花粉萌发量少、花粉管生长异常及花粉管生长停滞。除有髯鸢尾×西伯利亚鸢尾合子前障碍严重外,其余组合花粉管均能到达胚珠完成受精,合子前障碍不是有髯鸢尾系间杂交的主要障碍。2)有髯鸢尾与西伯利亚鸢尾杂交后败育速度快于与鸢尾杂交,有髯鸢尾系间杂交与亲缘关系呈正相关。3)有髯鸢尾×鸢尾的最佳胚拯救时期为授粉21 d后,鸢尾×有髯鸢尾为授粉24 d后,西伯利亚鸢尾×有髯鸢尾为授粉12 d后。合子后障碍是有髯鸢尾系间远缘杂交的主要障碍,通过胚拯救可获得鸢尾有髯鸢尾系间远缘杂交后代。本研究通过解析有髯鸢尾系间远缘杂交障碍及胚拯救研究,为培育适应性更高...     

Galactose toxicity in the chick: hyperosmolality

Galactose-fed chicks have been found to develop severe hyperosmolar dehydration. Although biochemical abnormalities have been observed in the brain of the galactose-toxic chick, the observed physiologic alteration of serum osmolality could be the major factor responsible for the galactose toxicity syndrome in the chick.     

Adrenergic innervation of the parasympathetic ciliary ganglion in the chick

The chick ciliary ganglion receives a nonvascular symathetic innervation in addition to the well-known cholinergic one; fluorescent, varicose adrenergic fibers form pericelluar baskets. Adrenergic fibes were identified electron microscopically in ganglia fixed with potassium permanganate. The fibers degenerate after injection of 6-hydroxydopamine. No true synaptic relationships involving adrenergic varicosities and ganglion cells or cholinergic terminals were demonstrable. The distribution of the adrenergic fibers suggests a kind of "distance à synapse" with the choroidal cells or with the preganglionic fibers (or both). The adrenergic innervation might provide a modulation of the cholinergic transmission.     

Amniotic contraction and embryonic motility in the chick embryo

During part of the incubation period of chick embryos the amnion shows spontaneous contractions. Removal of the amnion on days 9, 10, and 11 has no effect on the amount of, or the cyclic aspects of, motility exhibited by the embryo. These observations question the importance of the amnion and yolk-sac as stimulative factors in the initiation and maintenance of cyclic embryonic motility at the ages studied.     

Diphenylhydantoin: effects on calcium metabolism in the chick

Rickets, hypocalcemia, decreased duodenal calcium transport, and reduction of calcium binding protein have been produced in chicks treated with diphenylhydantoin. These effects are directly related to diphenylhydantoin dose and inversely related to the intake of vitamin D(3) (cholecalciferol).     

鸡大肠杆菌病的流行病学研究进展

鸡大肠杆菌病是由大肠埃希氏菌所引起的局部或全身性感染的传染病,可以引起胚胎死亡、脐炎、败血症、肉芽肿、全眼球炎、气囊病、腹膜炎、输卵管炎等一系列病症,并且还常常与病毒和其它细菌性疾病并发,造成鸡群的高死亡率,给养禽业造成了严重的经济损失。由于该病在一些鸡场中严重发生,兽医临床上抗菌药物不得不大量地被应用,导致大肠杆菌耐药菌株不断出现,耐药谱不断扩大,形成恶性循环;同时也加剧了抗菌药物在畜禽体内的残留,给养禽业的持续发展和人类的身体健康带来潜在危害。因此,开展鸡大肠杆菌的耐药性监测工作,加强耐药性机制的研究,…     

Biosynthesis of chick hemoglobins

In vivo studies of the biosynthesis of chick hemoglobins 1 and 2 showed an over-all higher incorporation of glycine-2-C(14), valine-4-C(14), valine-1-C(14), leucine-G-C(14), and histidine-(2-ring)-C(14) in hemoglobin 2; in vitro studies made with intact nucleated chick erythrocytes showed the higher incorporation of glycine-2-C(14), valine-1-C(14), and histidine-(2-ring)-C(14) in hemoglobin 1. Hybridization of chick hemoglobins produced an electrophoretically distinguishable new component.     

Silicon: an essential element for the chick

Silicon is required for normal growth and development in the chick when a low silicon diet is fed in a trace element controlled environment. Day-old deutectomized cockerels fed a purified amino acid diet showed significantly retarded growth and development within 2 to 3 weeks. Chicks fed the same diet plus a silicon supplement showed 50 percent higher growth and normal development. Silicon meets the criteria for an essential trace element.     

Testosterone concentration in the male chick brain: an autoradiographic survey

Differential uptake of [(3)H]testosterone in male chick brain was found in periventricular areas of preoptic-hypothalamic continuum. Concentration of silver grains for all decapitation periods was especially high in the medial preoptic area, particularly the nucleus praeopticus paraventricularis magnocellularis. Distribution of testosterone-sensitive cells is in agreement with studies showing neuroanatomical control of reproductive behavior by the avian forebrain.     

雏鸡中脑视顶盖Ⅰ层细胞构筑研究

为进一步阐明鸟类视觉通路的结构特征, 试验采用Golgi-Cox法, 灌流固定后尼氏体(Nissl bodies)染色和羰花青荧光染料DiⅠ(1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbo-cyanine perchlorate)逆向神经标记技术,对雏鸡视顶盖Ⅰ层的厚度和该层的细胞形态、大小进行了观察研究和数理统计.结果表明,Ⅰ层细胞多数呈梭形,还有少数呈圆形、椭圆形、锥形、三角形和不规则形状等.Ⅰ层外侧部较背侧部和腹侧部厚.按照胞体面积大小将细胞分为4类:巨细胞、大细胞、中细胞和小细胞,Ⅰ层背侧、腹侧和外侧以巨细胞最少,其中背侧、腹侧以小细胞为主,外侧以中细胞数量最多.Ⅰ细胞具有2～6个主树突,其中有2个主树突的细胞最多(60.7%, n=128).