Effects of cycloheximide on thymidine metabolism and on DNA strand elongation in Physarum polycephalum

Treatment of Physarum polycephalum with cycloheximide during the DNA synthesis period resulted in a reduction in the incorporation of [³H]thymidine into DNA. This effect was caused by both a reduction in the specific activity of TTP and by an inhibition of progeny strand elongation within replication units. No effect of the drug on the initiation of synthesis of replication units or on the ligation of DNA fragments was detected.     

Components of Partial Disease Resistance in Wheat Detected in a Detached Leaf Assay Inoculated with Microdochium majus using First, Second and Third Expanding Seedling Leaves

The use of first, second and third expanding seedling leaves of wheat (L1, L2 and L3 respectively), inoculated with conidial suspensions of Microdochium majus (syn. Microdochium nivale var. majus) in a detached leaf assay, for detecting components of partial disease resistance (PDR) was investigated across a range of wheat cultivars. Incubation periods (period from inoculation to first appearance of symptoms; a dull grey–green water‐soaked lesion) and latent periods (period from inoculation to the first appearance of sporodochia) were longest and lesions smallest on L3. The expression of PDR components on L2 was intermediate to those on L1 and L3. The longer latent periods on L3 typically occurred after leaf senescence contrasting with latent periods on L1 and L2 where sporulation most frequently occurred on relatively green leaf tissue. Cultivar differences in the first appearance of symptoms, incubation period, which occurred before any leaf senescence was observed, correlated significantly across all leaf positions. Similarly cultivar differences in latent period were correlated for L1 and L2. However, latent periods on L3, which were the least consistent between cultivars across experiments, were not correlated with those of L1 or L2 in any experiment. The results indicate that due to the delay in sporulation until after leaf senescence, observations on latent period in L3 are less representative of what occurs in the whole plant where infection of living tissue is of greatest interest. This work indicates that the selection of the first or second expanding leaf of wheat is optimal for the use in the detached leaf assay using M. majus for studying components of PDR.     

北京地区夏大豆田间杂草的生态经济杀除阈期研究

本文提出了杂草生态经济杀除阈期的概念,并在北京地区田间试验的基础上,建立了苗后放任和免除夏大豆田间杂草生长的相对时间与大豆相对产量间的函数关系,并在此基础上确立了夏大豆田间杂草群落的生态经济杀除阈期的计算模型。结果表明,夏大豆田间杂草的相对生态经济杀除阈期约处在大豆出苗至成熟期总天数的12.4%—31.0%的天数之前。在此期间进行除草,既能确保大豆不会因杂草生长而显著减产,又可节约阈期之前和之后盲目除草所消耗的费用,并在一定程度上可利用杂草的固土保肥、增加土壤有机质等作用。     

A study of the macro-environment at BenCat in southern Vietnam

Based on the meteorological data over a period of 4 years (1980–3), the macro-environment of BenCat Farm situated in the southern part of Vietnam (27 m above mean sea-level, 11° N and 106° E) was categorized as a “monsoon tropical climate”, due to heavy rainfall (annual mean 2028.96 mm) and about 32% wet days (annual mean 116.52 days) together with high air temperature (annual mean daily temperature 28.58, max. 32.33 and min 24.85° C). April was the hottest (monthly mean >35°C) and January the coldest month (monthly mean <22° C) of the year. The maximum number of wet days were during September and October (mean 18 days.month), whereas the minimum number of wet days were during January and February (mean <1 day/month). The months of December and January at Ben-Cat buffalo farm were categorized as the “comfortable (moderate-Dry) period” as the mean daily temperature was <27° C, while the remaining 10 months of the Calender year (February–November) were categorized as the “hot period” (mean daily temperature >27° C). On the basis of rainfall and the number of wet days, the hot period was further subdivided into a “hot-dry period” (February–April, mean of 1.67 wet days/month and mean rainfall 19.43 mm/month) and a “hot-humid period” (May–November, mean of 15.57 wet days/month and mean rainfall 276.28 mm/month).     

我国丹顶鹤栖息地选择研究进展

丹顶鹤(Grus japonensis)是我国Ⅰ级重点保护野生动物,被世界自然保护联盟列为濒危物种。本研究通过搜集和整理2000至2017年丹顶鹤栖息地选择和生境适宜性相关文献,分析了丹顶鹤在繁殖期、迁徙期、越冬期的栖息地选择,发现丹顶鹤在这三个时期的最偏好生境均为芦苇沼泽或芦苇滩,回避人为干扰较为严重的居民点、道路、盐田等生境。通过梳理丹顶鹤繁殖地、中途停歇地、越冬地的栖息地变化及其原因,发现丹顶鹤栖息地变化是自然因素和人为因素共同驱动的结果,以人为因素为主。本研究希望为科学评价栖息地变化对丹顶鹤野生种群的影响、针对性地开展栖息地保护管理工作、促进丹顶鹤野生种群健康可持续发展提供依据。     

The Effects of Temperature on the Incubation and Latent Periods of Powdery Mildew (Erysiphe polygoni) on Clematis

The effects of temperature on the length of the incubation and latent periods of clematis powdery mildew, caused by Erysiphe polygoni , were studied. At constant temperatures over the range of 10–29°C, the length of the incubation period ranged from 4 to 11 days, and the length of the latent period ranged from 4 to 13 days; no visible colonies developed at 30°C after 19 days. The relationship between temperature and the rates of fungal development within the incubation and latent periods (expressed as the reciprocal of the lengths of the incubation and latent periods) under constant temperature were described well by a non-linear model. The resulting curves were not the usual form of an asymmetrically bell-shaped type; instead, they were of exponential type with the development rate increasing with increasing temperatures. The relationship between temperature and the development rate during the post-incubation (before sporulation) period was non-linear with an optimum temperature of approximately 20°C.     

一类传染病动力学时滞模型的分析

研究了一类传染病动力学模型,用摄动理论讨论了相应的非线性时滞问题,得到了被传染病感染的人群数与健康人群数比例的变化规律的渐近表达式,从而揭示了传染病的潜伏期和传染期对疾病传播的影响和作用.本文的研究为解决这一类非线性时滞模型提供了一种有效的方法.     

夏大豆田稗草的生态经济防治阈期研究

本文提出了杂草生态经济防治阈期的概念。并在北京地区１９８４和１９８５年田间试验的基础上,建立了苗后放任的免除夏大豆田稗草生长的相对天数与大豆相对产量的函数关系及其生态经济防治阈期的计算模型。利用此模型计算的结果表明,夏大豆田稗草的生态经济防治阈期处在大豆苗后生育期总天数的１６．８％－２６．０％之间,即按绝对天数计算,北京地区夏大豆田该杂草的生态经济防治阈期约处在大豆苗后１５－２３ｄ之间,此期保持无     

Relationship between latex yield of Hevea brasiliensis and antecedent environmental parameters

A study on the relationship between latex yield and antecedent environmental data was undertaken for five clones (RRII203, RRII118, RRIM600, RRII105 and GT1) of Hevea brasiliensis (rubber) in Agartala, northeast India, a region in which rubber is not traditionally cultivated. The explained variance for the regression equations based on parameters determined on the day of tapping and up to 3 days prior to it, varied from 72% to 37% during the NWT period and 94-83% during the WT period. Soil moisture storage, 1 and 3 days prior to tapping, was found to be the primary parameter affecting yield for the NWT and WT periods, respectively. It was observed that the clone RRII105, with a comparatively lower yield to that of RRIM600, was more susceptible to daily WD conditions during the non-winter season. RRIM600 and RRII105 being high-yielding clones were also found to be fairly dependent on the AT of the day prior to tapping. The mean lag period correlation of this parameter with yield was also found to be higher during the WT period than during the NWT period. As a whole, the mean lag period based on prior measurements of environmental variables showed optimum correlation with yield at 15-20 days prior to the day of tapping. The study also confirms that varied responses of yield with environmental factors in this non-traditional region of rubber cultivation depend on clonal character.     

泽雅水库混合深度的年内变化及其对藻类生消影响

就水库藻类水华的发生机制而言,近年来值得关注的研究动向是,一些研究者开始认识到光照和混合的交互作用可能对藻类水华生消过程起到了关键作用,即认为水体混合深度的变化直接影响着可获得光强,从而决定着藻类生物量的时空分布。在这些研究中,混合层深度的确定是探讨藻类生消过程影响的前提。然而已有的研究大都只进行粗略的估计。本文提出采取系统聚类分析的方法确定泽雅水库不同时期的混合深度。在具体分析过程中,将测得的某一天某一深度处的pH,DO,温度,电导率,氧化还原电位等5个参数结果看成一类,采用类间平均连接法,间隔尺度变量为欧氏距离的平方进行聚类。对采用系统聚类分析法和已有的"1°C"法计算得的全年的混合深度的变化趋势进行比较,认为系统聚类分析法可以更为准确地反应水体混合的实际情况。依据混合深度的不同特征,在年内水库水体可划分为热成层时期,全混时期和两者之间的过渡期,藻类生物量与混合深度呈负相关。在热成层期间,藻类生物量都超过了13mm³L^-1。而到了9月份,当混合层深度扩展到15m以上时,藻类生物量明显下降,此后水体处于全混时期,藻类生物量较低,在9-20mm³/L^-1波动。基于稳态假设的前提下,发现随着混合深度增加,稳态藻类生物量呈单峰变化,在混合深度2m处达到最大值,即在混合深度为0-2m之间时,藻类沉降作用是藻类生物量的主要影响因素,随着深度增加,沉降作用下降,因此藻类生物量增加;当混合深度超过2m之后,光限制作用占主导因素,藻类生物量随混合深度增加而下降。这一结果为 Diehl的假说提供了水库现场的实证。     

The history of cereals in the region of the former Duchy of Swabia (Herzogtum Schwaben) from the Roman to the Post-medieval period: results of archaeobotanical research

Archaeobotanical results from the investigations of cereal finds in southwestern Germany and northern Switzerland have been mapped. Seven phases are distinguished, from Roman to early modern (Post-medieval). Methodological problems are discussed concerning sampling, identification, preservation, type of site, feature and assemblage, which influence the representation of the results. The main results are as follows. In the Roman period, Triticum spelta was the main crop, except in the upper Rhine valley (Oberrheinebene) where T. aestivum was more abundant. In the Migration period and Early Medieval period several crops are of similar importance. The reason was a rather simple economic system, a subsistence economy for each village, and perhaps cereal and grassland rotation (Feld-Gras-Wirtschaft). In the High Medieval period, Secale cereale was the dominant grain in the northern part of the region up to the Danube (Donau). In Switzerland, T. spelta dominated. In the landscape in between, from Lake Constance (Bodensee) to the upper Neckar valley, there was a mixture of both. These rather clear spectra, commonly dominated by one cereal species, express the changed economic system: the three field system (Dreifelderwirtschaft) and an increasing role of the market economy. Even in the Late Medieval and Post-medieval periods S. cereale and T. spelta remained the main crops. The present dominance of T. aestivum and Hordeum vulgare is a very recent development, less than a century old. The less important cereals, T. monococcum and Panicum miliaceum, occur regularly until Post-medieval times. T. dicoccum was very rare in this region from the Roman period onwards.     

Agriculture and food from the Roman to the Islamic Period in the North-East of the Iberian peninsula: archaeobotanical studies in the city of Lleida (Catalonia, Spain)

The urban archaeological excavations carried out in the city of Lleida (Catalonia, Spain) have opened the way for an interdisciplinary project on the ancient landscape, agriculture and food. Here we present the results of the archaeobotanical study of seeds and fruits from this project, centred on the Roman and Islamic periods of the city, between the 2nd century B.C. and the 11th century A.D. During the whole of this period the cultivation and consumption of cereals was found. The most important cereals were hulled barley and naked wheat. This was already known from the later prehistoric era in the area and is similar to findings at other sites from the same period in the western Mediterranean. These cereals are accompanied by some leguminous crops and the presence of grapes and figs is very significant. The expansion of vine cultivation, together with a certain amount of tree growing was one of the basic contributions of the Roman world to proto-historical (Bronze- and Iron Age) agriculture in western Catalonia, as in other parts of Europe. In the Islamic period, there seems to have been an increase in the number of fruit tree species; however for taphonomical reasons this has to be confirmed by future investigations. Flax, already known in prehistoric times, and Gold-of-pleasure must be added to the finds. Also since the Roman period some other taxa, such as celery or fennel, might have been grown. During the time period considered in this paper, there was a wide range of plants grown and consumed. This clearly contrasts with everything known about earlier periods in western Catalonia, during which the only cultivated plants were cereals and flax.     

黑化诱导激素对白薯天蛾的发育影响

黑化诱导激素是一种神经肽,它像激素一样调控昆虫的生长发育。给五龄白薯天蛾注射较高浓度的黑化诱导激素时,它们的吐丝期明显延长,蛹重也明显增加。给五龄各天白薯天蛾注射136pmol每克体重的黑化诱导激素,它们的添食期、吐丝期延长,蛹重增加。因此,黑化诱导激素会延长天蛾幼虫的添食期和吐丝期,影响天蛾幼虫的发育。     

真菌学的二百五十年*

本文对真菌学的发展历史作了简要的回顾并将其分为4个发展阶段:(1)前真菌学阶段(B.C.5000—A.D.1700);(2)古真菌学阶段(1701—1850);(3)近代真菌学阶段(1851—1950);(4)现代真菌学的发展(1951—现在)。     

高原鼢鼠繁殖期和非繁殖期的行为比较

本文在室内饲养条件下对高原鼢鼠（Myospalax baileyi）非繁殖期和繁殖期的行为进行了观察,定性、定量地对16中行为进行了描述和分析。结果表明,这两个时期的行为基本没有变化,但行为发生的频次和持续时间有极大的不同。个中行为的时间的分配在24小时内及其在两个不同时期之间均有一定的差异,而每小时内动物的主要行为表现为睡眠和休息、移动、取食、挖掘、相互接触。繁殖期,动物的活动时间增加,表现为挖掘活动和接触时间的加长,动物社会行为发生的频次和持续时间高于非繁殖期。     

真菌学的二百五十年

本文对真菌学的发展历史作了简要的回顾并将其分为4个发展阶段:(1)前真菌学阶段(B.C.5000—A.D.1700);(2)古真菌学阶段(1701—1850);(3)近代真菌学阶段(1851—1950);(4)现代真菌学的发展(1951—现在)。     

Critical periods for developmental acclimation to cold in the Queensland fruit fly, Dacus tryoni

Rapid acclimation to cold can occur in Dacus tryoni during two short stages of its life history: the stage immediately prior to the “hopping larva” phase and the “pharate adult” stage within the puparium. Transfer from 25 to 15°C at either of these stages can produce full acclimation to cold within a few days. Acclimation is not detectable at other times in puparial life: during adult life it takes over 100 days.     

Life history,immunity, Peto's paradox and tumours in birds

Cancer and tumours may evolve in response to life‐history trade‐offs between growth and duration of development on one hand, and between growth and maintenance of immune function on the other. Here, we tested whether (i) bird species with slow developmental rates for their body size experience low incidence of tumours because slow development allows for detection of rapid proliferation of cell lineages. We also test whether (ii) species with stronger immune response during development are more efficient at detecting tumour cells and hence suffer lower incidence of tumours. Finally, we tested Peto's paradox, that there is a positive relationship between tumour incidence and body mass. We used information on developmental rates and body mass from the literature and of tumour incidence (8468 birds) and size of the bursa of Fabricius for 7659 birds brought to a taxidermist in Denmark. We found evidence of the expected negative relationship between incidence of tumours and developmental rates and immunity after controlling for the positive association between tumour incidence and body size. These results suggest that evolution has modified the incidence of tumours in response to life history and that Peto's paradox may be explained by covariation between body mass, developmental rates and immunity.     

亚洲玉米螟成虫寿命与繁殖力的地理差异

为探明亚洲玉米螟Ostrinia furnacalis繁殖力的地理差异,比较了亚洲玉米螟5个不同地理种群海南乐东(LD)、江西南昌(NC)、山东泰安(TA)、河北廊坊(LF)和黑龙江哈尔滨(HEB)的成虫寿命、产卵历期、产卵量,并分析了这些参数与各种群地理纬度的关系.成虫寿命随纬度升高而延长,从南到北各种群雌虫寿命分别为10.20、13.68、13.90、13.95 d和16.40 d,雄虫寿命分别为8.35、12.50、13.62、13.71 d和14.30 d;产卵历期随纬度升高而延长,从南到北各种群分别为7.45、10.45、11.90、10.62d和13.15 d;产卵量随纬度升高而增大,乐东产卵量显著低于其他种群,从南到北各种群产卵量分别为351.55、500.09、522.90、546.76粒和577.95粒/雌.这些研究结果初步揭示了亚洲玉米螟繁殖略策的地理差异.     

中国稻谷可培养真菌群落组成及多样性

真菌生长导致粮食品质下降及真菌毒素污染,是造成粮食损失的主要原因。我们采用形态学与分子系统发育分析相结合的方法,对中国13个省78份稻谷样品的真菌群落组成及多样性进行研究。结果表明,本次共分离622株真菌,经初步鉴定分属于17属73个物种。南北方因气候条件差异较大,稻谷真菌数量和物种组成都存在很大差异。南方稻谷表面真菌数量（10 ⁴cfu/g）明显高于北方（10 ³cfu/g）。北方收获期的优势种主要属于枝孢属Cladosporium,南方收获期的优势种为黄曲霉Aspergillus flavus、黑曲霉Aspergillus niger和阿姆斯特丹曲霉Aspergillus amstelodami等。进入储藏期后,由于中国仓储管理要求较高,储藏环境相对稳定（aw≤0.75）,耐旱真菌阿姆斯特丹曲霉和多育曲霉Aspergillus proliferans（占比40%以上）成为优势种,这类真菌可作为储藏期粮堆异常的早期预警指示菌。南方收获期感染的黄曲霉和黑曲霉进入储藏期后仍保持优势比例,导致储藏期间毒素污染风险必然增加,因此南方稻谷收储环节均应加强监管。本研究通过分析南北方收获和储藏环节稻谷真菌群落组成差异及产毒真菌的分布规律,以期为中国粮库在稻谷收储环节的真菌毒素防控提供依据。