落羽杉与墨西哥落羽杉3个杂交后代品系的生长和杂种优势分析

以落羽杉〔Taxodium distichum(Linn.)Rich.〕和墨西哥落羽杉(T.mucronatum Tenore)及其3个杂交后代品系'中山杉405'('Zhongshansha 405')、'中山杉406'('Zhongshansha 406')和'中山杉407'('Zhongshansha 407')2年生盆栽扦插苗为研究对象,对株高和地径的年增长量、总叶面积、株高和地径的增长量动态变化、株高和地径的生长期进行了比较分析,并根据地径增长量分析了3个杂交后代品系的杂种优势.结果表明:3个杂交后代品系的年株高增长量介于父本与母本之间但无显著差异,而三者的年地径增长量和总叶面积则明显高于父本和母本.墨西哥落羽杉与3个杂交后代品系的株高和地径生长期均一致,分别为5月11日至10月5日和6月1日至11月9日;而落羽杉的株高和地径生长期分别为5月11日至8月10日和6月8日至11月16日.5月份至10月份,墨西哥落羽杉的株高持续增长,而3个杂交后代品系的株高不连续增长,落羽杉的株高则在8月10日之后停止生长;生长初期和生长末期,3个杂交后代品系的地径增长量均高于父本和母本;秋季3个杂交后代品系均能快速进行地径生长,而此时父本和母本的地径增长量均下降.除夏季的少数时间段外,'中山杉405'在整个生长季都表现出明显的杂种优势,而'中山杉406'和'中山杉407'在整个生长季总体上表现出杂种优势,且它们的杂种优势最大值均出现在生长后期,说明供试的3个杂交后代品系在秋季也能快速生长.研究结果显示:供试的3个杂交后代品系均遗传了落羽杉地径生长迅速和墨西哥落羽杉株高生长期长的特性,秋季3个杂交后代品系的地径和株高增长量总体上均高于父本和母本,表现出明显的杂种优势.     

数字照片在树干解析上的应用

介绍了一种利用摄影测量技术开展树干解析的新方法.通过求算横截面积,换算成理论直径及年轮宽度.此法可以提高测量精度,特别是在树干横截面不规则的情况下,可以提高准确度.选择一个基本圆满的圆盘,直接测量直径和由面积换算比较年轮宽度,二者差异平均为10%,最大达32%.由于图像上直接测量的是面积,树皮的横截面可以更加准确获得,而传统的方法无法克服这个缺点.数字照片还是储存年轮信息的理想形式,便于保存和复查.本法使用的是普通的数码照片,方便适用,是开展森林精密测量简单易行手段.     

Effect of type of semen, time of insemination relative to ovulation and embryo transfer on early equine embryonic vesicle growth as determined by ultrasound

Embryonic vesicle growth in the mare is easily monitored by ultrasound. Apart from pregnancy diagnosis, assessment of the embryonic vesicle in practice is also useful to evaluate its viability. Although subject to individual variation, embryo growth rate follows a constant pattern in the early stages of development in relation to embryonic age. Previous studies have shown a significant effect of some factors routinely used in practice, such as post-ovulation insemination and embryo transfer, on embryonic growth and the time in which the vesicle is first detected. This study attempts to confirm previous results in different settings and characterise the causes for this delay in growth. A total of 159 pregnancies from different mating protocols: (1) pre-ovulation natural mating, (2) pre-ovulation natural mating and transfer into recipient mares, (3) post-ovulation natural mating, and (4) post-ovulation AI with frozen/thaw spermatozoa were evaluated ultrasonographically from day 12 to 19 of pregnancy and vesicle diameters recorded. Regression analysis between embryonic vesicle diameters and embryonic ages was performed for each group and mean vesicle diameter at different age periods among groups were tested for statistical difference with a general linear model of variance. There was no significant difference between groups 1 and 2 (P = 0.73) or between groups 3 and 4 (P = 0.71). However both pre-ovulation groups (1 and 2) had larger vesicle diameters (P < 0.000) at any embryonic age analysed than either of the post-ovulation groups (3 and 4). In conclusion, post-ovulation inseminations produced pregnancies with smaller vesicle diameters equivalent to approximately 1 day's growth.     

帽儿山天然次生林10种主要阔叶树冠径与胸径关系研究

根据帽儿山天然次生林30块标准地每木检尺的实测数据,建立帽儿山天然次生林10种主要阔叶树冠径与胸径以及胸径和冠径与胸径比值（cd/D）之间的关系,并且简要论述冠径与胸径比值在树木空间、断面积和林分密度和间伐强度的应用。研究表明：胸径在10~30 cm之间,相关系数（R²）在0.8以上时,冠径与胸径关系近似一条直线。通过对不同树种的不同大小树木(cd/D)比值的分析,得出随着胸径的增加的比值是逐渐减小的,并且减小的趋势随着胸径的增加趋于平稳,最后趋于一个常数。     

Effects of geometry on transmission and sensing potential of tapered fiber sensors

Geometry of tapered fiber sensors critically affects the response of an evanescent field sensor to cell suspensions. Single-mode fibers (nominally at 1300 nm) were tapered to symmetric or asymmetric tapers with diameters in the range of 3–20 μm, and overall lengths of 1–7 mm. Their transmission characteristics in air, water and in the presence of Escherichia coli (JM101 strain) at concentrations of 100, 1000, 7000 and 7 million cells/mL were measured in the 400–800 nm range and gave rich spectral data that lead to the following conclusions. (1) No change in transmission was observed due to E. coli with tapers that showed no relative change in transmission in water compared to air. (2) Tapers that exhibited a significant difference in transmission in water compared to air gave weak response to the presence of the E. coli. Of these, tapers with low waist diameters (6 μm) showed sensitivity to E. coli at 7000 cells/mL and higher concentration. (3) Tapers that showed modest difference in water transmission compared to air, and those that had small waist diameters gave excellent response to E. coli at 100–7000 cells/mL. In addition, mathematical modeling showed that: (1) at low wavelength (470 nm) and small waist diameter (6 μm), transmission with water in the waist region is higher than in air. (2) Small changes in waist diameter (0.05 μm) can cause larger changes in transmission at 470 nm than at 550 nm at waist diameter of 6 μm. (3) For the same overall geometry, a 5.5 μm diameter taper showed larger refractive index sensitivity compared to a 6.25 μm taper at 470 nm.     

黄土高原子午岭天然柴松林种群结构与动态研究

对黄土高原地区子午岭天然柴松(Pinus tabulaeformisf.shekannesis)林种群的结构和动态进行了研究。结果显示:柴松种群结构呈反J分布型,种群处于增长阶段;种群的密度随径级的增加而降低,种群密度与径级呈现出明显的负相关;4个函数(生存率函数、积累死亡率函数、死亡密度函数、危险率函数)估计值说明种群具有前期增长、后期稳定的特点,其存活曲线介于DeeveyⅡ型和DeeveyⅢ型之间;随时间推移,种群中树和大树数量逐渐增多,种群在20 a后开始大量进入成熟阶段。表明柴松在本研究区内生长更新良好,在无人为干扰条件下,柴松可通过自我调节能力而保持种群的稳定性。     

腐烂等级和径级对天宝岩长苞铁杉林木质残体理化性质的影响

木质残体是森林生态系统的重要组成部分,其理化性质影响木质残体的分解.本研究以集中分布于天宝岩国家级自然保护区的长苞铁杉(Tsuga longibracteata)林木质残体为对象,将4个不同类型林分的木质残体划分为5个腐烂等级和4个径级,研究林分类型、腐烂等级、径级及其交互作用对木质残体理化性质的影响.结果 表明:从物...     

Role of myosin light chain kinase and myosin light chain phosphatase in the resistance arterial myogenic response to intravascular pressure

The intrinsic ability of vascular smooth muscle cells (VSMCs) within arterial resistance vessels to respectively contract and relax in response to elevation and reduction of intravascular pressure is essential for appropriate blood flow autoregulation. This fundamental mechanism, referred to as the myogenic response, is dependent on apposite control of myosin regulatory light chain (LC₂₀) phosphorylation, a prerequisite for force generation, through the coordinated activity of myosin light chain kinase (MLCK) and myosin light chain phosphatase (MLCP). Here, we highlight the molecular basis of the smooth muscle contractile mechanism and review the regulatory pathways demonstrated to participate in the control of LC₂₀ phosphorylation in the myogenic response, with a focus on the Ca²⁺-dependent and Rho-associated kinase (ROK)-mediated regulation of MLCK and MLCP, respectively.