Melatonin: a coordinating signal for mammalian reproduction?

There is a daily rhythm in the production of the pineal hormone melatonin in all mammalian species. Production is stimulated by darkness and inhibited by light. This provides a signal reflecting the changing environmental lighting cycle. In seasonally breeding mammals that use changes in the photoperiod to time their reproductive cycles, temporal signals to the reproductive system are controlled by the daily rhythm in melatonin production.     

Comment on "Erosion of lizard diversity by climate change and altered thermal niches"

Using a regionally calibrated model, Sinervo et al. (Reports, 14 May 2010, p. 894) predicted potential climate change impacts on lizard populations and estimated that many extinctions are under way. We argue that this model is not sufficient for predicting global losses in lizard species in response to anthropogenic climate change.     

Melatonin: its inhibition of pineal antigonadotrophic activity in male hamsters

Exposure of male hamsters to short daily photoperiods (1 hour of light and 23 hours of darkness daily for 9 weeks led to total involution of the testes and accessory sex organs (seminal vesicles and coagulating glands). Pituitary levels of immunoreactive prolaction also decreased by about 60 percent after dark exposure. The inhibitory effects of darkness on the reproductive organs were prevented either by pinealectomy or by the subcutaneous implantation of a melatonin-beeswax pellet into the animals each week. Both pinealectomy and melatonin treatment also returned pituitary levels of prolactin toward normal. The results suggest that melatonin is not the pineal antigonadotrophic factor in the male golden hamster.     

Adenosine 3'-5'-monophosphate in rat pineal gland: increase induced by light

Rats were maintained in alternating periods of 12 hours of light and 12 hours of darkness. The concentration of adenosine 3',5'-monophosphate in pineal gland was six times higher at the end of the light period than at the end of the period of darkness. This effect of light was abolished in blinded animals.     

Ethanol preference in the rat as a function of photoperiod

Ethanol-drinking was induced in laboratory rats that were maintained in total darkness. The established preference for ethanol was not reversed under conditions of constant illumination although a decrease in ethanol intake occurred. Administration of melatonin to rats maintained under "normal" photoperiods (9 hours of darkness during a 24-hour day) also induced ethanol-drinking.     

Potassium Channels in Samanea saman Protoplasts Controlled by Phytochrome and the Biological Clock

Leaflet movement in legumes depends on rhythmic, light-regulated ion fluxes in opposing regions of the leaf-moving organ. In flexor and extensor protoplasts from Samanea saman Merrill, opening and closing of K(+) channels were rhythmic in constant darkness. When channels were open in flexor protoplasts they were closed in extensor protoplasts, and vice versa. The rhythms were shifted by a delay in the onset of constant darkness, a response typical of endogenous circadian rhythms. During the light period, the channels in flexor protoplasts were sensitive to red light that was followed by premature darkness; phytochrome was implicated as the photoreceptor.     

Marsilea vestita: Conversion of the Water Form to the Land Form by Darkness and by Far-Red Light

A period in darkness or in continuous far-red light can cause the ferns of the species Marsilea vestita Hook. and Grev. to develop as a land form in a medium which normally allows only the water form to develop. Far-red light is more effective than darkness in causing this conversion. The difference in the quality of light reaching plants growing in water or on land may cause this conversion to occur in nature.     

氮磷钾运筹模式对北疆滴灌棉花生长发育和产量的影响

【目的】明确北疆滴灌棉花干物质积累及产量形成对氮磷钾综合运筹的响应特征,为节省氮肥成本提供依据。【方法】以鲁棉研24号为材料,在4种施氮量（506、402.5、299和195.5 kg·hm^-2,分别用N1、N2、N3和N4表示）和蕾期、花铃期4种不同磷钾肥运筹方式（100%+0,25%+75%,50%+50%和75%+25%,分别用PK-M1,PK-M2,PK-M3和PK-M4表示）下进行田间试验。试验期间测定棉花叶面积指数（LAI）、干物质积累、蕾花铃数量及产量等指标。【结果】在相同磷钾运筹方式下,随着施氮量的降低,LAI的Logistic模型K’值表现为先上升后下降趋势,N3比N2处理高5.1%—16.5%,快速增长起始期（t₁）和快速增长结束期（t₂）均为N3处理最晚,且N3处理快速增长期持续时间最长,N3处理比N2处理多2—12 d;N3处理生长特征值GT最高,N2处理次之,N3比N2处理高5.2%—16.7%;干物质积累量在生长前期表现为N1>N2>N3>N4处理,在生长后期表现为N2>N1>N3>N4处理;蕾花铃数在全生育期表现为N2>N3>N1>N4处理;产量相对值在各施氮处理下表现为N2处理最高,N3处理次之,N2处理比N3处理高3.6%—6.5%。在相同施氮量下,LAI的Logistic模型K’值最高为PK-M3处理,最低为PK-M1处理,PK-M3处理比PK-M1处理高20.5%—27.4%;快速增长起始期t₁(2019年除外)和快速增长结束期t₂均为PK-M3最晚,且PK-M3处理快速增长期持续时间（T）最长;PK-M3处理生长特征值（GT）最高,PK-M2处理次之,PK-M3处理比PK-M2处理高13.0%—24.5%;干物质积累量在生长前期表现为PK-M2处理>PK-M3处理>PK-M4处理>PK-M1处理,生长后期表现为PK-M3>PK-M2>PK-M4>PK-M1处理;蕾花铃数在生长前期表现PK-M4>PK-M3>PK-M>PK-M2处理,生长后期表现为PK-M3>PK-M2>PK-M4>PK-M1处理;产量相对值表现为PK-M3处理最高,比其他磷钾处理高5.2%—18.2%。所有处理中,N3PK-M3处理下LAI Logistic模型K’值和GT值最大,T最长,在吐絮期干物质积累量、相对产量值和后期蕾花铃数仅次于N2PK-M3处理,生殖器官干物质分配比例高于其他处理。相关分析表明,LAI在2018年播种后109 d以后和2019年播种后120 d以后与生殖器官干物质、干物质总量和相对产量呈极显著正相关,全生育期生殖器官个数、总干物质积累量、生殖器官干物质与相对产量均为显著或极显著正相关。所有处理中N2PK-M3产量最高,N3PK-M3处理次之,N3PK-M3相对产量仅比N2PK-M3处理降低1.5%。【结论】N3PK-M3处理与农户常规施氮量相比,减少25%的氮肥施用量仍能获得较高产量,可能是由于推迟了棉花后期LAI到达峰值的时期,延缓了LAI下降速率,提高棉花群体干物质生产能力,并促使其向生殖器官转运,且降低蕾铃脱落,保证后期铃数,为产量的形成提供物质基础。因此,本研究认为在蕾期和花铃期各分施50%磷钾肥的条件下,氮肥的施用量可以降低至299 kg·hm^-2,这比农户常规施氮降低25%,以达到减氮稳产、节本增效的目的。     

短期黑暗对矮牵牛幼苗叶片光合结构及功能的影响

以矮牵牛（Petunia hybrida）为试验材料,常温黑暗条件处理1、4d和15d,后两种处理在光照（PFD=150μmol·m^2·S^-1）下恢复4、8d和12d,对幼苗叶片显微结构、叶绿体超微结构及光合功能进行了研究。结果表明：（1）与0d相比,黑暗处理1、4d和15d叶片厚度分别下降9．9％、16．9％和36．2％;栅栏组织厚度黑暗处理1d有显著减小,海绵组织厚度黑暗处理4d后有显著下降。黑暗处理1d的幼苗叶片,叶绿体片层排列紧密但方向稍紊乱;黑暗处理4d,叶绿体片层排列扭曲变形,叶绿体内有空洞;黑暗处理15d,叶绿体内布满空洞,趋于解体。恢复光照,黑暗处理4d幼苗叶片显微结构及叶绿体超微结构完全恢复,15d幼苗基本恢复。（2）黑暗处理后叶绿素、Pn、Gs、Ci、Fv／Fm和F／Fo均显著下降,Fo显著上升。恢复光照,以上光合特性各值均基本恢复到正常水平。黑暗及恢复光照过程中叶绿素含量的变化主要取决于Chla,而Chlb保持相对稳定;黑暗处理4d幼苗光合作用的下降主要是由气孔限制所致,而15d幼苗光合作用的下降主要是非气孔因素造成。     

Rhythms in pheromone production of the male boll weevil

Male boll weevils, Anthonomus grandis, held in a light regimen of 16 hours of light and 8 hours of darkness released pheromone rhythmically during the 24 hours. The amount released during peaks was typically 20 times the amount released in valleys. The ratio of the two alcohol components of the pheromone also showed a daily rhythm. Under continuous light, both the release of pheromone and the ratio of the two alcohol components were arrhythmic. In darkness, pheromone release was diminished more than tenfold over the 20-day test period.     

大球盖菇漂烫液喷雾干燥精粉贮藏稳定性的研究

对大球盖菇漂烫液喷雾干燥精粉在贮藏期内物理性状、吸湿性和自由基清除性能的变化进行研究.结果表明:贮藏温度越低,大球盖菇漂烫液喷雾干燥精粉对·OH自由基清除率越高,半损失时间也越长,应在低温下储存且不应超过20℃;相同温度下无光照大球盖菇漂烫液喷雾干燥精粉比光照的半损失时间更长,采取措施减少光照有利于延长精粉的贮藏时间,应尽量避光保存;不同湿度下吸湿速率存在差异,相对湿度越高,吸湿性变化越快;不同湿度下的理论包装时间较充足,在相对湿度达到92.31％条件下包装时间长0.34 h,因此防止吸湿回潮是精粉产品贮藏的一个重要问题.试验结果表明,大球盖菇漂烫液喷雾干燥精粉在低温、低湿及避光条件下具有良好的贮藏稳定性.     

光暗处理对水稻叶片光合关键酶的效应

稻苗置暗中24h后,Rubisco含量及Rubisco与可溶性蛋白的比值随光强的增加而提高;经2h光照后再置黑暗中,Rubisco含量在最初20min下降迅速,说明苗期Rubisco蛋白在光暗交替下周转较快.Rubisco的初始活力在光照下迅速增加,其上升倍数大大高于量的增加,光强越大达到最大活力所需的时间越短.照光后把稻苗置暗中,Rubisco初始羧化活力很快下降,说明Rubisco的光下活化及暗中失活迅速.Rubisco活化酶的含量随光照增加而逐渐上升,光照处理后再置暗中Rubisco活化酶含量不断下降,但速率不如Rubisco.Rubisco活化酶的活化只依赖低光强,光照处理后再置黑暗中,Rubisco活化酶活力迅速下降.     

暗处理和钾营养对水稻~(14)CO_2同化及其产物输出的影响

在两种钾水平下,研究了暗处理对缺钾敏感品种的~(14)CO_2同化及同化产物输出的影响。结果表明,经暗处理后,水稻植株对CO_2的固定,孕穗期在两种钾水平下均明显下降;灌浆期低钾植株CO_2固定明显降低。常量钾处理的标记植株的总放射性活度高于低钾处理的植株,并随暗处理时间的缩短而增加,光与钾有助于光合产物向谷粒中分布。叶片中糖含量,灌浆期多于孕穗期。在自然光照下,常量钾植株的含糖量多于低钾处理,暗处理则低钾多于常量钾处理。叶片中ATP含量,在正常光照与暗处理下低钾处理均高于常量钾处理。暗处理与人工24小时光照使标记叶光合产物的输出量减少,而钾营养则促进光合产物的输出。     

Newts: sun-compass orientation

Rough-skinned newts, captured from breeding ponds, oriented on courses that would have intersected the familiar shorelines at right angles, when released in a circular arena on land under the sun or moon. Pondward migrants oriented similarly. Reorientation failed under complete cloud cover and after 7 days of darkness in an environmental chamber, but persisted in newts whose eyes were excised and in those displaced more than 27 kilometers in darkness. Both normal and blind animals compensated for displacement in sunshine. Preliminary evidence suggests that alternative light receptors in blinded animals may be associated with the optic tectum. No evidence of olfactory guidance was observed.     

Effect of zeolites on adaptation processes in cows

The possibility of using Khotynets natural zeolites for preventing the development of oxidative stress and correcting disorders in the antioxidant system of cows when treating diseases of the reproductive system and under unfavorable housing and feeding conditions during the winter stabling period is shown.     

长座虫草子实体的人工诱导研究

首次应用长座虫草的无性型—长座被毛孢对长座虫草子实体的生长条件进行了研究,并确立了最佳的培养工艺。结果表明,长座被毛孢液体摇瓶最佳培养时间为9 d,在营养液中添加10%的动物性蛋白(黄粉虫粉)有助于提高子实体产量,其所需营养液最佳pH为6.0,培养温度为25℃,初期菌丝培养时间为完全黑暗培养,待菌丝长满后给予1～200 lx连续光照,可获得更多的子实体。     

Parietal eye nerve in the fence lizard

A nerve from the parietal eye of the western fence lizard, Sceloporus occidentalis, is described as leaving inconspicuously from the third-eye and extending caudally under the dura mater and then ventrally along the left anterolateral surface of the epiphysis to the habenular commissure of the brain. The existence of a parietal nerve must be considered in interpreting the effects of parietalectomy.     

水稻自噬相关基因OsATG7的功能

通过对OsATG7突变体、OsATG7超表达及干涉转基因植株表型的观察,对OsATG7突变体进行暗胁迫处理并观察自噬体产生情况,检测OsATG7、SGR基因的表达量以及叶绿素含量变化,阐述水稻细胞自噬基因缺失对水稻生长发育的影响。结果显示:OsATG7基因与水稻育性相关,OsATG7基因的缺失导致水稻高度不育;OsATG7基因可以抵抗黑暗对水稻的非生物胁迫作用,随着暗胁迫时间的增加,水稻OsATG7基因表达量显著上升,该基因的缺失导致水稻衰老相关基因SGR表达量急剧上升,叶绿素流失加速,使植株表现出提早衰老的现象。     

不同覆盖作物对砂姜黑土剖面硝态氮动态的影响

为探究不同覆盖作物整个生育期内[覆盖作物播种后（2021年11月5日）、营养生长期（2022年3月12日）和生殖生长期（2022年5月5日）]砂姜黑土剖面中硝态氮的动态变化,本研究在安徽省龙亢农场典型砂姜黑土区设置压实（Compacted,C）与不压实（Non-compacted,NC）处理,并裂区设置冬季休闲（Con）、苜蓿（Alf）、油菜（Rap）、萝卜+毛苕子混播（Rhv）4个处理,动态监测0～120 cm土层中土壤硝态氮含量、储量和植株地上地下生物量及其氮素积累量。结果表明：整个覆盖作物生长季,Alf、Rap、Rhv处理土壤硝态氮含量持续下降,各处理0～120 cm土层平均分别下降43.3%、53.9%、57.5%。营养生长期与生殖生长期3个覆盖作物处理（除生殖生长期不压实条件下Rhv处理）硝态氮储量均较Con处理降低（P<0.05）,且营养生长期的平均降幅（压实52.7%,不压实60.7%）高于生殖生长期（压实40.2%,不压实35.6%）。营养生长期,不压实条件下Alf处理土壤硝态氮储量是Rap和Rhv处理的1.41倍（P<0.05）。生殖生长期,压实与不压实条...     

贵州梵净山尖叶拟船叶藓生物量的生殖配置

以贵州梵净山尖叶拟船叶藓Dolichomitriopsis diversiformis为材料，对尖叶拟船叶藓种群各个生长期生殖器官和营养器官生物量配置进行了季节动态研究。结果表明，营养生长期和休眠期植株不生长生殖器官，因此这2个时期的生物量配置为0，生殖生长期生物量配置为0．74％，生殖前期生物量配置分别为雌器苞占0.57％，幼孢子体占2．36％，生殖期生物量配置为4．77％，生殖后期生物量配置为6．67％。图1表2参9