光照时间对水蔗草兼性无融合生殖的影响

在水蔗草花序发育期间给予不同时间的光照处理后,对其花粉育性,结实率和无融合生殖频率的研究表明,（1）花粉育性在不同光照时间下无显著差异。（2）减少1h和2h光照时间的结实率和对照相比无明显变化。（3）增加1h和2h光照时间,花序发育受到抑制,抽穗延迟,只有极少数花序发育成熟,产生的种子很少。（4）在自然光照时间和增加1h光照时间条件下,无融合生殖的频率在0.41-0.64之间;在减少1h和2h及增加2h的光照条件下,无融合生殖的频率在0.19-0.22之间,和对照及增加1h光照处理相比,无融合生殖频率显著下降。     

植物生长调节剂对水稻光敏核不育系培矮64S育性恢复的作用(简报)

一定剂量的CoCl2、IAA和2,4-D以及与GA3配合叶面喷施或根部水施后,水稻培矮64S的育性在不育条件下得到部分恢复。其中以浓度各为50mg／L的2,4-D和GA3配合进行根部水施效果最好自交结实率提高达7.9％。     

高州普通野生稻主要生殖性状的数理统计分析

高州野生稻各采样点的生殖特性表现出明显的多样性。对141份野生稻的花粉育性、裂药指数、胚囊育性和结实率进行通径分析。结果表明,花粉育性、裂药指数和胚囊育性决定了结实率变异的61．17％,其中裂药指数对结实率的直接作用最大,通径系数为0．6495;花粉育性和胚囊育性对结实率的直接作用较小,通径系数分别为0．2356和0．2137,花粉育性通过裂药指数还有较大的间接通径系数（0．2960）。通过系统聚类,将高州普通野生稻分为4群,并时各群进行方差分析和邓肯氏多重比较,可归纳为：Ⅰ群的花粉育性、胚囊育性和裂药指数对结实率影响小;Ⅱ群主要由胚囊育性影响结实率;Ⅲ群主要由裂药指数影响结实率;Ⅳ群主要由花粉育性和裂药指数共同影响结实率。     

提高狗蔷薇离体培养植株再生频率

以狗蔷薇（Rosa canina Inermis）为材料,以MS为基本培养基,通过对不同植物生长调节剂的组合,大幅度提高了狗蔷薇离体培养植株再生频率。结果表明,2．0mg／L 6-BA＋0．3mg／L 2,4-D的组合较为适宜,其不定芽再生率为87％,增殖率为3．0;而CPPU和2,4-D的适宜组合为1．5mg／L＋0．3mg／L,其不定芽再生率高达93％,增殖率为5．0。同时,研究结果显示,以MS＋40g／L蔗糖＋6．0g／L琼脂粉＋3．5mg／L AgNO3＋1．5mg／L CPPU＋0．1mg／L 2,4-D＋0．05mg／L GA3作增殖培养基效果最好,不定芽诱导率为89％,增殖率为5．5;利于生根的培养基为1／4MS＋20g／L蔗糖＋3．5g／L琼脂＋0．3％活性碳＋0．1mg／L IBA＋0．1mg／L NAA,生根率为91％。     

水蔗草兼性无融合生殖胚胎学研究

对水蔗草(Apluda mutica L.)的生殖方式进行研究,结果表明水蔗草进行兼性无融合生殖.胚囊发育分为两种类型,即有性生殖的蓼型和无孢子生殖的大黍型.无融合生殖胚囊频率为60.74%.在大孢子母细胞发育至四分体后,珠孔端的3个大孢子解体.合点端的大孢子未解体时,邻近大孢子的1个珠心细胞开始特化,形成无融合生殖的原始细胞,由该原始细胞发育形成有1个卵细胞、1个助细胞和2个极核的四核胚囊.     

水蔗草兼性无融合生殖胚胎学研究

对水蔗草 (ApludamuticaL .)的生殖方式进行研究 ,结果表明水蔗草进行兼性无融合生殖。胚囊发育分为两种类型 ,即有性生殖的蓼型和无孢子生殖的大黍型。无融合生殖胚囊频率为 6 0 .74%。在大孢子母细胞发育至四分体后 ,珠孔端的 3个大孢子解体。合点端的大孢子未解体时 ,邻近大孢子的 1个珠心细胞开始特化 ,形成无融合生殖的原始细胞 ,由该原始细胞发育形成有 1个卵细胞、1个助细胞和 2个极核的四核胚囊。     

中华结缕草(Zoysia sinica Hance)组织培养和再生植株研究

以中华结缕草(Zoysia sinica Hance)成熟种子为外植体在附加2．5mg／L2,4-D、0．25mg／L 6-BA和1～2mg／L VB1的改良MS培养基(MSm)上愈伤组织的诱导率最高为43．0％。愈伤组织的最佳继代培养基为MSm附加0．1mg／L 6-BA和2．0mg／L 2,4-D。在无生长调节物质的MS培养基(MS0)上,外观呈白色到淡黄色、含有密实颗粒的愈伤组织再生率为30％～60％。     

绿巨人白掌不同外植体组织培养研究

本文研究白鹤芋属观赏品种绿巨人白掌的茎顶、叶片、叶柄和幼花序的组织培养和快速繁殖技术。茎顶培养以0.2mg／LNAA 3．0mg／L6-BA培养效果较好;叶片诱导适宜的培养基为0．5mg／LNAA 5．0mg／L6-BA,分化培养基为0．2mg／LNAA 3．0mg／L6-BA;叶柄以0．5mg／L2,4-D 3．0mg／L6-BA诱导效果最好,分化适宜培养基为0．5mg／LNAA 3．0mg／L6-BA;幼花序胚状体的诱导则以0．5mg／L2,4-D 5．0mg／L6-BA效果最好,成苗培养基为0.5mg／LNAA 3．0mg／L6-BA;255mg／L的KH2P04比较／比较适合于绿巨人白掌丛芽的增殖;生根培养基以1／2MS 0.50mg／LNAA较适宜。     

土壤水分亏缺对水蔗草兼性无融合生殖的影响

无融合生殖是植物界中普遍存在的一种不经过精卵结合而产生种子的特殊生殖方式.水蔗草是禾本科水蔗草属的一种多年生草本植物,我国西南、华南等地均有分布,是广东、云南、海南等稀树草原常见的伴生植物.常生于海拔2 000 m以下的田边、水旁湿地及山坡草丛中.营养期草质柔嫩,可作饲料;根可治疗毒蛇咬伤.我们曾报道过水蔗草进行兼性无融合生殖,胚囊发育分为有性生殖的蓼型和无孢子生殖的大黍型两种类型     

中国假俭草结实性的比较分析

本文以中国有代表性的58份假俭草[Eremochloa ophiuroides(Munro)Hack．]种源为试验材料,以假俭草品种‘Common’和‘TifBlair’为对照,对中国假俭草的种子产量及其组分进行了统计分析。结果表明：中国假俭草种子产量平均为15．1g／m^2,花序密度平均为1510个／m^2,平均结实率为54．4％,平均百粒重0．086g,单位花序小花数平均为20．2。各组分变异系数从大到小依次为：花序密度、结实率、百粒重和单位花序小花数。假俭草种子产量高低主要由花序密度决定,结实率和百粒重也对种子产量有一定的作用,而单位花序小花数对种子产量贡献很小。不同种源种子产量存在显著性差异,产自重庆渝北的E092种源种子产量极显著高于品种‘Common’、“TifBlair’及其他种源;有14份种源的种子产量在24．8—39．5g／m^2范围内,均高于品种‘Common’,但均未达到显著水平;有17份种源的种子产量高于品种“TifBlair”,但也均未达到显著水平。     

Blood Clotting and Platelet Aggregation during Oral Progestogen Contraception: A Follow-up Study

A two-year follow-up study of progestogen-only contraception with chlormadinone acetate indicates no increase of the level of factors VII and X, as found after three cycles with all oestrogen-progestogen oral contraceptives. Clotting factors which were raised with combined preparations became normal after the sixth monthly cycle of progestogen and remained normal during the two-year period of study.From 12 months onwards significant changes in the thromboelastograph pattern were recorded, but not to the same extent as with combined preparations. At two years platelet aggregation was significantly accelerated with chlormadinone acetate but was not as rapid as with combined preparations.     

Data Mining in the U.S. National Toxicology Program (NTP) Database Reveals a Potential Bias Regarding Liver Tumors in Rodents Irrespective of the Test Agent

Long-term studies in rodents are the benchmark method to assess carcinogenicity of single substances, mixtures, and multi-compounds. In such a study, mice and rats are exposed to a test agent at different dose levels for a period of two years and the incidence of neoplastic lesions is observed. However, this two-year study is also expensive, time-consuming, and burdensome to the experimental animals. Consequently, various alternatives have been proposed in the literature to assess carcinogenicity on basis of short-term studies. In this paper, we investigated if effects on the rodents’ liver weight in short-term studies can be exploited to predict the incidence of liver tumors in long-term studies. A set of 138 paired short- and long-term studies was compiled from the database of the U.S. National Toxicology Program (NTP), more precisely, from (long-term) two-year carcinogenicity studies and their preceding (short-term) dose finding studies. In this set, data mining methods revealed patterns that can predict the incidence of liver tumors with accuracies of over 80%. However, the results simultaneously indicated a potential bias regarding liver tumors in two-year NTP studies. The incidence of liver tumors does not only depend on the test agent but also on other confounding factors in the study design, e.g., species, sex, type of substance. We recommend considering this bias if the hazard or risk of a test agent is assessed on basis of a NTP carcinogenicity study.     

Trophic Role of the Moose (Alces alces L.) Population and Its Effect on the Nitrogen and Carbon Cycles in a Southern Taiga Spruce–Birch Forest

Biology Bulletin - The results of a two-year study conducted to assess the outcomes of a long-term forest isolation experiment are presented. A section of a spruce–birch forest in Yaroslavl...     

Impacts of Canopy and Understory Nitrogen Additions on Stomatal Conductance and Carbon Assimilation of Dominant Tree Species in a Temperate Broadleaved Deciduous Forest

Ecosystems - Excess N deposition has aroused concerns about its negative impacts on forest ecosystems. A two-year study was conducted to assess the responses of stomatal conductance (Gc) and carbon...     

Étude observationnelle SCOPE: suivi sur deux ans d’une cohorte française de patients souffrant d’un trouble schizophrénique ou schizoaffectif; analyse en cluster et taux de rechute

The main objective of the SCOPE observational study was to follow-up a cohort of 833 schizophrenic or schizoaffective patients treated for an acute state over a two-year period. A cluster analysis using the Ward method was performed at baseline using gender, age, diagnosis, length of illness, CGI-S and PANSS scores to determine clusters. Five clusters have been identified that underline the importance of gender differences in schizophrenia on one hand, and on the other, the heterogeneity of schizoaffective disorders which include patients near to schizophrenia, while other patients seem to belong to the bipolar spectrum. The two-year relapse rate in the total population was 32.7%. Data concerning relapse rates within each cluster are in line with the patient’s typology. Our results lend support to the validity of this method of analysis in psychiatry.     

高原鼠兔挖掘活动对植物种的丰富度和地上生物量的影响

用空间序列代替时间序列的方法,分析了高原鼠兔挖掘形成的鼠丘上和鼠丘间植物群落物种丰富度、物种组成和地上生物量的变化,探讨鼠兔挖掘活动对植物群落的影响。结果表明:多年鼠丘上植物种类丰富度较高,分别比两年鼠丘和对照增加25. 0% 和17. 5% ;多样性指数变化趋势为对照> 多年鼠丘> 两年鼠丘,种的均匀度变化趋势为对照>多年鼠丘> 两年鼠丘;两年鼠丘和多年鼠丘、对照之间群落系数较低,分别为0.346 2和0.285 7,显示了它们在植物种类组成上存在较大差异;地上生物量变化趋势为多年鼠丘> 两年鼠丘> 对照,且多年鼠丘上植物地上生物量显著高于两年鼠丘和对照(F_{多年- 对照}= 13.544 0,F_{多年- 两年}= 11.768 2,P < 0. 05),分别增加了66.3% 和77. 8% 。高原鼠兔的挖掘活动有利于增加物种丰富度和自身的适应性,但就高原鼠兔栖息地植物群落而言,考虑到一定数量当年鼠丘的存在,地上生物量呈下降趋势。     

南阳牛DGAT2基因PCR-RFLP多态性及其与生长性状相关性研究

以131头纯种南阳牛为研究材料, 利用PCR－RFLPs对二酰甘油酰基转移酶2(DGAT2)基因的第6内含子和第7内含子的多态性及其与生长发育的相关性进行了分析。结果表明: 南阳牛在该位点分别检测到两种等位基因A/B和N/M, 频率分别为0.875/0.125和0.971/0.029。A和N等位基因是群体中的优势等位基因。该基因内含子6对南阳牛6月龄的体高、2岁体重、6月龄到两岁的胸围和体斜长都有显著的影响, 内含子6的AA基因型的6月龄的体高比杂合型高3.8 %, 两岁体重高3.9%, 6月龄到两岁的胸围分别高3.8%、3.4%、3.7%、4.3%; 6月龄到两岁的体斜长分别高3.8%、3.6%、3.8%、3.1%。内含子7对18月龄和两岁的坐骨端宽有极显著的影响(P<0.01); 对两岁的胸围有显著的影响(P<0.05)。     

CLEANSOIL as a perspective method of remediation of oil-contaminated soils under existing infrastructure

The results are given of the two-year study of the new technology of soil remediation from oil contamination-CLEANSOIL combining physicochemical and biological methods of eliminating oil pollution. It is shown that using this combined technology results in quick decrease in the oil concentration in soil to the level when the soil is able to clean itself.     

人工栽培山莨菪和野生山莨菪中4种托烷类生物碱含量的比较研究

为了评估人工栽培山莨菪的药用价值,采用高效液相色谱技术对人工栽培和野生山莨菪的地上部分和根中具有生物活性的4种托烷类生物碱：樟柳碱、山莨菪碱、东莨菪碱和阿托品的含量进行了测定。结果表明无论是人工栽培还是野生植物,地上部分中4种生物碱含量均远低于根,这解释了人们为什么用山莨菪的根而不是整株人药。在栽培植物的根中,一年生山莨菪中各生物碱含量均小于二年生山莨菪,其根中4种生物碱总量与野生根相比差异不是很明显;二年生山莨菪根中,4种生物碱总量以及樟柳碱、东莨菪碱和阿托品含量均比野生的高。这说明人工栽培的山莨菪,尤其是二年生山茛菪,同野生山莨菪一样具有一定的药用价值。     

Population cycles caused by overcompensating density-dependence in an annual plant

Summary We analyse demographic data from a seven-year study of the annual crucifer Erophila verna which showed two-year cycles of abundance in the field. The unusual behaviour of this population is shown to be the consequence of overcompensating density-dependence. Very local differences in germination succes between plots can account for observed differences in their population dynamics over the long term.