常绿阔叶树种栲树开花物候动态及花的空间配置

 基于定株观测和随机枝取样法,对浙江天童常绿阔叶林内栲树（Castanopsis fargesii）的开花物候动态及其雌花、雄花的空间配置进行了研究。结果表明：在栲树的生殖枝上,并非所有的芽都分化、萌发生成花序,栲树花芽的分化和发育集中在一级生殖枝上。生殖枝上花芽的分化与该枝的空间位置密切相关。栲树花期明显晚于春季的展叶期,与叶片生长时间重叠。盛花期集中于5月下旬,约持续8 d左右,属于同步发生的花期。栲树雄花序的数量明显高于雌花序,雄花序约占花序总数的77.88%,雌花序仅占22.12%。大量雄花和花粉的存在是保证雌花接受花粉和完成受精的基础。花序在植冠层中的空间配置明显不同：在同一植冠内,向阳面和背阴面生殖枝上芽萌发成花序的比率存在明显差异(p<0.01),阳面生殖枝上顶芽萌发成花序的比率高于阴面生殖枝的比率,并且,阳面的每个生殖枝上平均花序数和雄花数量均高于阴面生殖枝,花序的分化和发育与枝系的生长发育状况有密切关系。     

白桦的开花时间及生殖构件的数量与树龄和树冠层次的关系

白桦的初始开花结实年龄在不同生境、不同起源情况下是有很大差别的。在相同地生境下,实生苗比萌生苗的始花年龄晚６ａ以上,中生生境的林分始花期要早于湿生生境的林分,在同一年中花期的早晚因林龄而异。花序构件种群、生殖技构件种群以及生殖枝花序数量都与树龄直接相关。花序构件数量壮年期〉老龄期〉结实初期。在同一生殖个体上,构件数量雄花序为中层〉上层〉下层,雌花序数量为土层〉中层〉下层,每个生殖枝平均的花序构件数     

间伐强度对黄桥林区辽东栎生殖构件的影响

为了阐明抚育间伐强度对辽东栎生殖构件的影响,以黄土高原南部黄龙和桥山林区辽东栎中龄林为研究对象,对不同间伐强度(对照、10%、20%、30%)下近自然经营抚育间伐5年后的辽东栎平均单株个体大小、生殖构件产量、比率及空间分布格局特征等进行研究.结果表明: 间伐强度对辽东栎林分平均树高、胸径影响不显著,而与冠幅面积、冠幅体积呈显著正相关;辽东栎标准株的生殖枝、幼果、成熟果实产量随间伐强度的增大而增大,而营养枝、雄花序、雄花、雌花的产量变化不大.当间伐强度达到20%时,生殖枝、幼果、成熟果实产量显著提高,30%间伐下达到最大.生殖枝比例和座果率随间伐强度增大而增大,在20%、30%间伐强度时与对照的差异达到显著水平.约3/4的生殖枝、雌花、雄花集中分布于树冠上层,1/4分布于下层;树冠阳面生殖构件数量占65%,树冠阴面占35%.树冠下层、阴面生殖枝、雌花、雄花序的空间分布比例随着间伐强度的增大而增大;树冠上层、阳面生殖枝、雌花、雄花序分布比例随间伐强度的增大呈递减趋势.因此,选择30%间伐强度(保留郁闭度0.6)最佳,可以大幅提高辽东栎的座果率和成熟率,有效提高结实量和品质,为辽东栎林的采种及天然更新提供保证.     

胡杨、灰叶胡杨花空间分布及数量特征研究

研究了不同居群的胡杨、灰叶胡杨花空间分布及其数量特征。结果表明,无论是胡杨还是灰叶胡杨,其雄树的树高、最低花位、集花区下限、集花区上限、最高花位皆低于雌树,并且雌株与雄株的花序分布范围亦有着较大的重叠区域。在树体上,雄花序主要分布在树冠的中部,上部次之,下部最少;雌花序主要分布在树冠的上部,中部次之,下部最少。胡杨的单株花序量、花朵花药数、花药花粉量和花序花粉量均小于灰叶胡杨,而花序花朵数胡杨雄树的小于灰叶胡杨,雌树的大于灰叶胡杨。统计分析表明,不同居群胡杨的单株花序量、花序花朵数与花药花粉量是相对稳定的,而灰叶胡杨仅雄树的单株花序量是稳定的。     

小叶桦花序生长物候及其生态适应意义

小叶桦(Betula microphylla)是一种典型的荒漠和山地乔木植物,在中国仅分布于新疆。为了明确小叶桦花序生长物候规律及发育特征,该研究对小叶桦进行了花序物候观测,分析其生长规律及果实结籽情况。结果显示:小叶桦雄花序为越年生殖器官,物候周期为345d,其中营养生长期154d、休眠期158d、开花生长期33d;雌花序与果序为当年生殖器官,物候期为105d,其中雌花序生长期24d、果序生长期90d。虽然雄花序比雌花序的生长周期明显较长,但开花授粉均在4月中下旬,雄花序散粉期和雌花序可授粉期之间具有较高的同步性和协调性,表现出集中开花授粉模式,同时这种开花模式在自然条件下,果序的结籽数和结籽率分别为220和76.7%,种子库中具有活力的种子约每平米4万粒,表明小叶桦在荒漠极端环境中能顺利完成有性生殖过程。     

天仙果与两种隐头花序小蜂的相互关系

天仙果（Ficus erecta var.beecheyana）花为单性花、雌、雄异株、分别形成雌、雄花序,雌花序着生雌花,雄花序着生雄花和瘿花。花序中生活着银纹榕小蜂（Blastophaga silverstriana）和榕长尾小蜂（Sycoscapter sp.）。前者是唯一能进入雄花序腔产卵或雌花序腔传粉的昆虫,是天仙果专一性共生的传粉者;后者不能进入花序,在花序外通过产卵器将卵产在瘿花子房中,是植食性的寄生者。自然状态下天仙果每个雄花序均被2种小蜂产卵,平均每个花序出飞银纹榕小蜂208.2只、榕长尾小蜂64.2只。人为封堵花序口,银纹榕小蜂无法进入花序产卵,平均每个花序出飞榕长尾小蜂165.6只,是自然状态下的2.5倍,显然,2种小蜂互为竞争对手,榕长尾小蜂是榕-榕小蜂共生体系的破坏者。     

雌雄异株植物长梗柳传粉系统和生殖策略研究

为探讨长梗柳(Salix dunnii)的传粉系统和不同性别的生殖投资策略,对居群性别比例、花部特征和访花昆虫进行了调查和观察,采用气相色谱-质谱联用技术(GC-MS)检测了花序的挥发性成分。结果表明,东边村居群的性别比例显著偏雄性(♂∶♀=1.28∶1, P < 0.05), 郭墩村和高地村的居群的性别比偏离不显著; 长梗柳雄株枝条的花序数显著多于雌株, 单花序的雄花数显著多于雌花, 雌花序平均长度显著大于雄花序; 长梗柳传粉系统是虫媒和风媒混合传粉系统, 主要访花昆虫为中华蜜蜂(Apis cerana)且显著偏好访问雌花; 吸引中华蜜蜂的挥发成分β-石竹烯的相对含量在雌花序中显著高于雄花序, 雌花序还具有β-榄香烯和芳香醇等吸引中华蜜蜂的特有挥发成分。因此, 长梗柳雄株在开花阶段投入了较多的资源产生雄花, 可能利于风媒传粉; 而雌株通过增加吸引传粉者的挥发成分来抵抗“传粉者限制”的效应, 可能利于虫媒传粉, 通过风媒和虫媒有效组合提升其繁殖效率。     

我国山毛榉科植物中一个新分布的属——三棱栎属

乔木。三叶轮生具成对合生的叶柄间托叶,或叶互生具离生的托叶。花序穗状,自正常和退化两者叶的腋中生出,单性,雄花序位于下方而雌花序位于上方,或仅有雄花序,簇状,或为雌雄同序下方具雄花而上方具雌花。雄花序挺直或曲折。雄花:(1—)3—7朵簇生,每簇具1基生和2侧生苞片;花被具6个复瓦状裂片,裂片下部合生;雄蕊6,与花被裂片对生,花药大(如栎属Quercus),宽卵圆形,基部心形,近背着但不为丁字着;退化雄蕊缺失。雌花:单生或3(—7)朵簇生,两种情况下承以3枚     

濒危植物长柄双花木自然种群生殖构件的时空动态

根据野外观测数据,研究了濒危植物长柄双花木(Disanthus cercidifolius var.longipes)在不同生境条件下自然种群开花物候变异以及生殖构件的时空动态.结果表明,不同群落类型中长柄双花木开花物候存在一定差异,在纯林中个体的平均花期最长,达75d,而个体间开花同步性最低,仅为0.717;竹林中的个体花期最短,只有47d,而同步指数最高,达0.968.生殖枝数量及花序数均随个体年龄增长而增加,在年龄为30～35年时达最高,此后又呈下降趋势;在海拔为810m左右处,个体生殖枝数及着生的花序数均达最大值,且冠层间差异明显.纯林中个体着生的生殖枝数及每生殖枝上着生的花序数均最高,分别为411.39和7.857;竹林中个体每生殖枝着生的花序数显著低于其它群落.年龄小的个体,各时期生殖构件败育率均高于年龄大的个体;另外,生殖构件的败育与海拔高度间无相关性,而与构件发育时间、分布的树冠层次以及所处的群落类型相关.影响生殖构件败育的主要因子是光照条件.     

爱玉子花的变异类型及其相关统计分析

该文报道了爱玉子(Ficus awkeotsang)花序中存在变异花的现象, 并通过花序解剖观测及数据统计分析方法, 研究比较雌、雄花序中变异花的类型、不同品系的花序变异率以及单花序中变异花的数量, 了解变异花发育过程、变异花与传粉小蜂之间的相互关系, 以及变异花对爱玉子产量造成的影响。结果表明: 爱玉子变异花在形态上有单生与伞形花序状2种类型, 雌花序中的变异花分布在雌花区和退化花区; 雄花序中的变异花均生长在瘿花区。雌花序中伞形花序状的A型变异花影响传粉小蜂对正常雌花的授粉, 与正常雌花争夺养分和生长空间从而影响正常雌花的生长发育, 大量A型变异花的存在使未授粉的雌花序延迟凋落或挂树不落, 造成养分流失。雌性品系太和6、太7、W13、乐野8、日野20和大洋Z106的花序中A型变异花数量较多, 对产量有一定的影响。除A型外的其它类型的变异花, 由于数量少且结构简单, 或发育后熟, 对传粉小蜂的传粉、产卵以及花序的发育、成熟没有显著影响。无论是雌性品系还是雄性品系, 以扦插苗繁殖方式形成的植株, 其花序变异率高于以实生苗繁殖方式形成的植株。以上研究结果为高产优质爱玉子品系的选育提供了一定的依据, 且对于爱玉子的栽培和推广有着重要的指导意义。     

Inter-breed variation in the postpartum ewe response to continuous low dose infusion of GnRH

During the nonbreeding season the pituitary and ovarian responses to a subcutaneous GnRH infusion were investigated in acyclic, lactating Mule ewes which exhibit a deep seasonal anestrus and in Finn x Dorset ewes in which seasonal anestrus is ill-defined. Each breed received 10 d of progestagen priming before being subdivided into 3 groups. In Group L + G, 5 lactating ewes received GnRH (250 ng/h sc) for 96 h; in Group D + G, 5 dry ewes received GnRH (250 ng/h sc) for 96 h; in Group L, 5 lactating ewes received saline vehicle for 96 h. The infusions began when lactating and dry ewes were approximately 28 d and 120 d post partum, respectively. Blood samples were collected for LH, progesterone and estradiol analysis. Estrous behavior was monitored between Day -4 and Day +7. On Day +7 the reproductive tract was also examined. In the Mule ewes the mean plasma LH concentration increased (P < 0.05) following minipump insertion in each treatment group, although mean LH levels were greater (P < 0.05) in Group D + G, than in either Group L + G or Group L. Following the GnRH infusion, mean plasma estradiol levels increased (P < 0.05) in Group D + G but not in Group L + G. A preovulatory LH surge and subsequent ovulation occurred in 5 5 , 2 5 and 0 5 ewes from Group D + G, L + G and L, respectively, and estrus was recorded in 5 5 , 1 5 and 0 5 of these ewes, respectively. The LH surges began earlier (P < 0.05) (43.2 +/- 6.8 h vs 77.0 +/- 1.0 h) and the ovulation rate was greater (2.2 +/- 0.37 vs 1.00 +/- 0.00) in Group D + G than Group L + G. In the Finn x Dorset ewes mean LH concentrations increased (P < 0.05), to a similar level following minipump insertion in Groups D + G and L + G, but not Group L. The elevated LH levels were accompanied by increased (P < 0.05) plasma estradiol levels in Group D + G, but not in Group L + G. The GnRH infusion culminated in an LH surge and estrous behavior in 5 5 , 1 5 and 0 5 ewes from Groups D + G, L + D and L, respectively. The interval to the LH surge was similar between Group D + G (48.4 +/- 6.6 h) and Group L + G (46.0 h). Ovulation was evident in those ewes which exhibited an LH surge plus one additional ewe from Group L + G. The mean ovulation rate was greater in Group D + G (4.00 +/- 1.05) than in Group L + G (1.5 +/- 0.50). These data show that continuous GnRH infusion can consistently induce out of season breeding in the nonlactating Mule and Finn x Dorset ewe but can not break combined seasonal and lactational anestrous in these breeds. Further, between-breed differences are evident in the site along the hypothalamic-pituitary-ovarian axis at which reproduction is compromised in ewes at the same chronological stage post partum.     

Mutation at the polymerase active site of mouse DNA polymerase delta increases genomic instability and accelerates tumorigenesis

Mammalian DNA polymerase delta (Pol delta) is believed to replicate a large portion of the genome and to synthesize DNA in DNA repair and genetic recombination pathways. The effects of mutation in the polymerase domain of this essential enzyme are unknown. Here, we generated mice harboring an L604G or L604K substitution in highly conserved motif A in the polymerase active site of Pol delta. Homozygous Pold1(L604G/L604G) and Pold1(L604K/L604K) mice died in utero. However, heterozygous animals were viable and displayed no overall increase in disease incidence, indicative of efficient compensation for the defective mutant polymerase. The life spans of wild-type and heterozygous Pold1(+/L604G) mice did not differ, while that of Pold1(+/L604K) mice was reduced by 18%. Cultured embryonic fibroblasts from the heterozygous strains exhibited comparable increases in both spontaneous mutation rate and chromosome aberrations. We observed no significant increase in cancer incidence; however, Pold1(+/L604K) mice bearing histologically diagnosed tumors died at a younger median age than wild-type mice. Our results indicate that heterozygous mutation at L604 in the polymerase active site of DNA polymerase delta reduces life span, increases genomic instability, and accelerates tumorigenesis in an allele-specific manner, novel findings that have implications for human cancer.     

Reproductive biology of alfonsino Beryx splendens

The main aim of this work is to provide a detailed analysis of the reproductive cycle of Beryx splendens in the Juan Fernández Archipelago. The gonadosomatic index (I(G) ) and maturity ogives in both sexes were estimated using an extensive database collected by onboard scientific observers between January 2006 and October 2009. A histological analysis of maturation was also completed for females collected between May and December 2001. Variations in both I(G) and proportion of mature individuals were observed in fish with a fork length (L(F) ) >37 cm for females and >33 cm for males. The main reproductive season was in the austral winter and spring (June to November). Fork length at 50% maturity (L(50) ) was estimated as 39·67 cm for females (95% c.i. =39·34, 40·02 cm) and 36·88 cm for males (95% c.i. =36·45, 37·36 cm) using macroscopic analysis of gonads. Estimates for females using histological data varied slightly with an estimated L(50) of 43·67 cm (95% c.i. =42·82, 44·91 cm). Changes in I(G) and maturity were modelled as a function of month and L(F) within a generalized additive model framework. A high porportion of immature individuals were found throughout the year. The results of this study are compared with reproductive traits reported for B. splendens in other areas of its distribution and are discussed with reference to exploitation, vulnerability and conservation of the B. splendens stock in Juan Fernández Archipelago.     

Intergenerational effects of birth weight on glucose tolerance and reproductive performance

Women who were themselves small-for-gestational age (SGA) are at a greater risk of adulthood diseases such as non-insulin-dependent diabetes mellitus (NIDDM), and twice at risk of having an SGA baby themselves. The aim of this study was to examine the intergenerational pig. Low (L) and normal (N) birth weight female piglets were followed throughout their first pregnancy (generation 1 (G1)). After they had given birth, the growth and development of the lightest (l) and heaviest (n) female piglet from each litter were monitored until approximately 5 months of age (generation 2 (G2)). A glucose tolerance test (GTT) was conducted on G1 pig at 6 months of age and again during late pregnancy; a GTT was also conducted on G2 pigs at 4 months of age. G1 L offspring exhibited impaired glucose metabolism in later life compared to their G1 N sibling but in the next generation a similar scenario was only observed between l and n offspring born to G1 L mothers. Despite G1 L mothers showing greater glucose intolerance in late pregnancy and a decreased litter size, average piglet birth weight was reduced and there was also a large variation in litter weight; this suggests that they were, to some extent, prioritising their nutrient intake towards themselves rather than promoting their reproductive performance. There were numerous relationships between body shape at birth and glucose curve characteristics in later life, which can, to some extent, be used to predict neonatal outcome. In conclusion, intergenerational effects are partly seen in the pig. It is likely that some of the intergenerational influences may be masked due to the pig being a litter-bearing species.     

Molecular recognition of the protein phosphatase 1 glycogen targeting subunit by glycogen phosphorylase

Disrupting the interaction between glycogen phosphorylase and the glycogen targeting subunit (G(L)) of protein phosphatase 1 is emerging as a novel target for the treatment of type 2 diabetes. To elucidate the molecular basis of binding, we have determined the crystal structure of liver phosphorylase bound to a G(L)-derived peptide. The structure reveals the C terminus of G(L) binding in a hydrophobically collapsed conformation to the allosteric regulator-binding site at the phosphorylase dimer interface. G(L) mimics interactions that are otherwise employed by the activator AMP. Functional studies show that G(L) binds tighter than AMP and confirm that the C-terminal Tyr-Tyr motif is the major determinant for G(L) binding potency. Our study validates the G(L)-phosphorylase interface as a novel target for small molecule interaction.     

The chemoattractant receptor-like protein C5L2 binds the C3a des-Arg77/acylation-stimulating protein

The orphan receptor C5L2 has recently been described as a high affinity binding protein for complement fragments C5a and C3a that, unlike the previously described C5a receptor (CD88), couples only weakly to G(i)-like G proteins (Cain, S. A., and Monk, P. N. (2002) J. Biol. Chem. 277, 7165-7169). Here we demonstrate that C5L2 binds the metabolites of C4a and C3a, C4a des-Arg(77), and C3a des-Arg(77) (also known as the acylation-stimulating protein or ASP) at a site distinct from the C5a binding site. The binding of these metabolites to C5L2 does not stimulate the degranulation of transfected rat basophilic leukemia cells either through endogenous rat G proteins or when co-transfected with human G(alpha 16). C3a des-Arg(77)/ASP and C3a can potently stimulate triglyceride synthesis in human skin fibroblasts and 3T3-L1 preadipocytes. Here we show that both cell types and human adipose tissue express C5L2 mRNA and that the human fibroblasts express C5L2 protein at the cell surface. This is the first demonstration of the expression of C5L2 in cells that bind and respond to C3a des-Arg(77)/ASP and C3a. Thus C5L2, a promiscuous complement fragment-binding protein with a high affinity site that binds C3a des-Arg(77)/ASP, may mediate the acylation-stimulating properties of this peptide.     

Adjustments in hydraulic architecture of Pinus palustris maintain similar stomatal conductance in xeric and mesic habitats

We investigated relationships between whole-tree hydraulic architecture and stomatal conductance in Pinus palustris Mill. (longleaf pine) across habitats that differed in soil properties and habitat structure. Trees occupying a xeric habitat (characterized by sandy, well-drained soils, higher nitrogen availability and lower overstory tree density) were shorter in stature and had lower sapwood-to-leaf area ratio (A(S):A(L)) than trees in a mesic habitat. The soil-leaf water potential gradient (psiS - psiL) and leaf-specific hydraulic conductance (kL) were similar between sites, as was tissue-specific hydraulic conductivity (Ks) of roots. Leaf and canopy stomatal conductance (gs and Gs, respectively) were also similar between sites, and they tended to be somewhat higher at the xeric site during morning hours when vapour pressure deficit (D) was low. A hydraulic model incorporating tree height, A(S):A(L) and psiS-psiL accurately described the observed variation in individual tree G(Sref) (G(S) at D = 1 kPa) across sites and indicated that tree height was an important determinant of G(Sref) across sites. This, combined with a 42% higher root-to-leaf area ratio (A(R):A(L)) at the xeric site, suggests that xeric site trees are hydraulically well equipped to realize equal--and sometimes higher potential for conductance compared with trees on mesic sites. However, a slightly more sensitive stomatal closure response to increasing D observed in xeric site trees suggests that this potential for higher conductance may only be reached when D is low and when the capacity of the hydraulic system to supply water to foliage is not greatly challenged.     

用定位突变探讨胰蛋白酶的稳定性

应用定位突变的方法,对鼠胰蛋白酶分子中易自溶位点的氨基酸残基进行改造,以探索提高胰蛋白酶稳定性的可能。将鼠胰蛋白酶原cDNA从质粒pTRAP上切下,插入载体M13mp8,在E.coli JM 101菌株中转化、复制后用以转染RZ1032缺陷型菌株,利用含U模板,进行按实验目的设计寡聚核苷酸引物引导的定位突变,将易自溶位点Ary105改造为Leu或Gly。经酶切和序列测定,证明在设计位点发生了预期的碱基突变。为了检查活性方便,又将含突变型胰蛋白酶cDNA从pTRAP上切下,插入另一个表达载体pTN中,转化入E.coli SM 138宿主中进行表达,表达产物分泌到围膜间隙,作专一性底物TAME活性胶方法检测,证明改造后的表达产物具有胰蛋白酶活性。对突变与野生型胰蛋白酶进行了初步比较。     

Maintenance of species boundaries in three sympatric Ligularia (Senecioneae,Asteraceae) species

The key process in speciation concerns the formation and maintenance of reproductive isolating barriers between diverging lineages. Although species boundaries are frequently investigated between two species across many taxa, reproductive isolating barriers among multiple species (>2) that would represent the most common phenomenon in nature, remain to be clarified. Here, we use double digest restriction‐site associated DNA (ddRAD) sequencing to examine patterns of hybridization at a sympatric site where three Ligularia species grow together and verify whether those patterns contribute to the maintenance of boundaries among species. The results based on the RAD SNP datasets indicated hybridization Ligularia cyathiceps × L. duciformis and L. duciformis × L. yunnanensis were both restricted to F₁s plus a few first‐generation backcrosses and no gene introgression were identified, giving rise to strong reproductive isolation among hybridizing species. Moreover, hybrid swarm simulation, using HYBRIDLAB, indicated the RAD SNP datasets had sufficient discriminatory power for accurate hybrid detection. We conclude that parental species show strong reproductive isolation and they still maintain species boundaries, which may be the key mechanism to maintain species diversity of Ligularia in the eastern Qinghai‐Tibetan Plateau and adjacent areas. Moreover, this study highlights the effectiveness of RAD sequencing in hybridization studies.     

Effects of edge/interior and patch structure on reproduction in Zostera marina L. in Chesapeake Bay,USA

We examined the effects of location (patch edge vs. interior) and shoot density (individual, patchy, continuous) on reproduction in three natural and two transplanted Chesapeake Bay (USA) stands of the submerged marine angiosperm Zostera marina L. (eelgrass; Zosteraceae). There were no edge effects on demographic-based reproductive effort or reproductive output (propagule production), and patch structure (individual, patchy, continuous) alone never accounted for the majority of variability in any metric. Transplant site was the most important predictor of eelgrass reproduction response, and relationships among metrics were predictable within sites. Our results suggest that, in Chesapeake Bay eelgrass, environmental factors acting at a regional scale (km) have a stronger impact on reproductive investment than those at a patch scale (1–10 m). Since tradeoffs between clonal and sexual production are mediated primarily by exogenous environmental factors, site selection may be more critical than transplant configuration for producing self sustaining stands, and achieving long-term restoration success.