Affinity difference of adenosine deaminases for the purine riboside-epoxyactivated Sepharose 6B column

The small-size adenosine deaminase (Mr = 35,000 and 43,000) in calf intestinal mucosa, frog liver and scallop adductor muscle and the large-size deaminase (Mr = 100,000) in frog liver probably formed by adding a conversion protein to the small enzyme, were tightly bound to the purine riboside affinity column. Binding of the other large-size enzymes (Mr = 140,000) in the midgut gland of scallop and mussel to the column was not successful. It seems that the binding difference does not depend on a change in affinity between active site and ligand but rather on the stereospecific positioning of active site in the enzyme molecules.     

从空间分布特征认识珍稀植物领春木的种群动态

领春木(Euptelea pleiosperrnum)系第三纪孑遗植物和东亚特有种,目前已被列为国家Ⅲ级重点保护植物.基于空间定位数据以最近邻体距离统计研究了神农架地区领春木的空间分布特征,比较幼苗(DBH≤2.5cm)、幼树(2.5～7.5cm)和成树(＞7.5cm)各径级(代表各生活史阶段)形成的时间序列上的空间格局差异,进而探讨空间格局与立苗、补员、种内竞争等种群动态过程的相互关系.结果显示,在邻域尺度上,领春木的空间格局呈聚集态;幼苗(或幼树)的大小与其距离最近幼树(或成树)的远近没有相关性,幼树(或成树)周围一定距离以内出现同等大小个体的概率约等于幼苗(或幼树)出现的概率,且幼树与最近幼苗(或成树与最近幼树)的平均距离与幼树之间(或成树之间)的平均最近邻体距离没有显著差异;任意个体的大小、任意个体与相应最近邻体的大小之和与相应的最近邻体距离均为显著的正相关关系,但幼树间的最近邻体距离并不大于幼苗随机死亡产生的最近邻体距离,成树间最近邻体距离也不大于幼苗+幼树随机死亡产生的最近邻体距离.这些结果表明,领春木的聚集分布可能与种子散布、生境异质性对立苗格局的作用有关;已定植的大个体可能不限制其邻域内小个体的布局与生长,但是长期的补员过程与邻体间的相互作用不无关系;邻体间存在一定程度的竞争作用,但是竞争强度并未充分激化至发生距离依赖的死亡.     

Effect of follicle size on in vitro production of steroids and insulin-like growth factor (IGF)-I,IGF-II,and the IGF-binding proteins by equine ovarian granulosa cells

Little is known regarding the hormonal regulation of granulosa cell steroidogenesis and the ovarian insulin-like growth factor (IGF) system in the mare. The objectives of this study were to determine, first, if estradiol, insulin, and/or FSH affect steroid production by equine granulosa cells (experiment 1) and, second, if the components of the IGF system are produced by equine granulosa cells in culture as well as whether estradiol, insulin, and/or FSH affects IGF and/or IGF-binding protein (IGFBP) production by equine granulosa cells (experiment 2). Granulosa cells from small (6-15 mm), medium (16-25 mm), and large (25-48 mm) follicles were collected from cyclic mares (n = 14), cultured for 2 days in medium containing 10% fetal calf serum, washed, and then treated for an additional 2 days in serum-free medium with or without added hormones. In experiment 1, large-follicle granulosa cells produced less progesterone and more estradiol than did medium- and/or small-follicle granulosa cells (P < 0.05). Progesterone production was inhibited (P < 0.05) by FSH and insulin in small- and medium- but not in large-follicle granulosa cells; estradiol was without effect. Insulin increased (P < 0.05) estradiol production in small- and medium-follicle granulosa cells but had no effect in large-follicle granulosa cells. In experiment 2, IGF-I production was inhibited (P < 0.05) by insulin across all follicle sizes but was not affected by estradiol or FSH. Granulosa cells of medium and large follicles produced more IGF-II than did granulosa cells of small follicles (P < 0.05). Insulin and FSH inhibited (P < 0.05) IGF-II production by granulosa cells of large and medium but not of small follicles; estradiol was without effect. Only IGFBP-2 and -5 were produced by equine granulosa cells. Production of IGFBP-2 was less (P < 0.10) in granulosa cells of large versus those of small and medium follicles, whereas medium-follicle granulosa cells produced more (P < 0.05) IGFBP-5 than did small- or large-follicle granulosa cells. Averaged across follicle sizes, estradiol increased (P < 0.05) IGFBP-2 production, FSH increased (P < 0.10) IGFBP-2 and -5 production, and insulin was without effect. These results indicate that IGF-I, IGF-II, IGFBP-2, and IGFBP-5 are produced by equine granulosa cells and that insulin, FSH, and estradiol play a role in the regulation of steroidogenesis and the IGF system of equine granulosa cells.     

黄土高原小流域淤地坝泥沙粒度的剖面分布

2006年6月,按照泥沙旋回分层连续取样,分析了黄土高原丘陵沟壑区典型小流域1954年修建的淤地坝泥沙粒径的剖面分布特征.结果表明：该坝地泥沙旋回至少28个,旋回层的厚度范围在2～60 cm;沉积剖面土壤粒径以粉砂（0.05～0.002 mm）为主,占60%以上,其粒径集中分布于0.01～0.05 mm,粗泥沙（粒径>0.05 mm）含量约占23.09%;随淤积深度的增加,泥沙各粒径范围的变异程度增加,2 m土壤深处可作为研究区淤地坝粒径变异突变点的标识,粒径变异是河道比降和水沙动力条件共同作用的结果;研究区淤地坝泥沙沉积剖面存在72 cm厚的累积耕作层,累积耕作层的明确对于淤地坝泥沙侵蚀环境具有指示作用.     

Intraspecific interactions influence size specific depth distribution in Cottus bairdi

Synopsis We tested depth selection by different sizes of mottled sculpin, Cottus bairdi, in a southern Appalachian stream. Field observations indicated that, during one hour periods, both small (<50 mm SL) and large (≥55 mm SL) individuals move within an area less than 0.50 m². Individuals of both sizes, placed in field enclosures, preferred deep microhabitat. When large fish were placed in cages with small fish, small fish initially spent more time in slope and shallow microhabitats. Average interfish distances were not correlated with their absolute size differences, suggesting C. bairdi interactions may involve both predation and competition. In streams, size-related differences in microhabitat depth may result more from intraspecific interactions than from size-specific depth preferences.     

Effects of substrate on interactions between juvenile sea scallops (Placopecten magellanicus Gmelin) and predatory sea stars (Asterias vulgaris Verrill) and rock crabs (Cancer irroratus Say)

We investigated the effect of substrate (glass bottom, sand, granule, pebble) on predation of juvenile sea scallops (Placopecten magellanicus) by sea stars (Asterias vulgaris) and rock crabs (Cancer irroratus) at two prey sizes (11-15 mm and 24-28 mm shell height), and two prey densities (10 and 30 scallops per aquarium) in laboratory experiments. Specifically, we quantified predation rate and underlying behaviours (proportion of time a predator spent searching for and handling prey, encounter rate between predators and prey, and various outcomes of encounters). We detected a significant gradual effect of particle size of natural substrates on sea star predation: specifically, predation rate on and encounter rate with small scallops tended to decrease with increasing particle size (being highest for sand, intermediate for granule, and lowest for pebble). Substrate type did not significantly affect predation rates or behaviours of sea stars preying on large scallops or of rock crabs preying on either scallop size classes. Other factors, such as prey size and density, were important in the scallop-sea star and scallop-rock crab systems. For example, predation rate by sea stars and crabs and certain sea star behaviours (e.g. probability of consuming scallops upon capture) were significantly higher with small scallops than with large scallops. As well, in interactions between small scallops and sea stars, predation rate and encounter rate increased with prey density, and the proportion of time sea stars spent searching was higher at low prey density than high prey density. Thus, substrate type may be a minor factor determining predation risk of seeded scallops during enhancement operations; prey size and prey density may play a more important role. However, substrate type still needs to be considered when choosing a site for scallop enhancement, as it may affect other scallop behaviours (such as movement).     

Postingestive selection in the sea scallop, Placopecten magellanicus (Gmelin): the role of particle size and density

Suspension-feeding bivalves can influence the energy value of their food supply by particle selection at various stages from particle clearance to production of feces. Previous workers have found that some bivalve species (Mercenaria mercenaria, Mytilus edulis) are capable of postingestive selection within the stomach. Few studies, however, have attempted to isolate the factors that influence postingestive selection. In this study, we examined the ability of the sea scallop Placopecten magellanicus to select particles within the stomach on the basis of physical properties. Scallops were presented with a mixture of three sizes of beads (5, 10 and 20 μm) or with a mixture of beads of different densities (1.05 g ml(-1) and 2.5 g ml(-1)). We demonstrate that P. magellanicus can distinguish between particles of different sizes and densities, retaining larger particles (20 μm) longer than smaller ones (5 μm) and lighter particles longer than denser ones. This ability to reject small, dense particles may benefit the scallop by reducing the amount of energy expended attempting to digest poor quality particles such as silt. This paper presents the first quantitative analysis of the effect of particle size and density on particle processing within intact bivalves.     

Granulosa cells from pig follicles of different sizes demonstrate maturational differences in their steroidogenic responses to FSH, calcium ionophore A23187, and phorbol diester

Cultures of granulosa cells from small (less than 3 mm), medium (3-6 mm), or large (8-10 mm) pig follicles were treated as follows: (1) basal controls, (2) cyclic adenosine 3',5'-monophosphate (cAMP) pathway agonists (pig FSH: 100 ng/ml; forskolin: 10 microM; dibutyryl cAMP; 1 mM), (3) calcium ionophore A23187 (0.005-1 micrograms), or (4) phorbol 12-myristate 13-acetate (TPA; 0.05-4 ng/ml). The combination of A23187 or TPA together with cAMP agonists was also examined in cultures of granulosa cells from follicles of different sizes. All substances were added at the time of culture, and oestradiol and progesterone were measured in the culture media after 48 h. All cAMP agonists were most potent in their stimulation of steroidogenesis (as a % of control) in cells from small follicles (P less than 0.05) with the exception of forskolin, which increased oestradiol in cells from large follicles to a greater extent than in cells of small follicles (P less than 0.05) (cells from medium follicles demonstrated less stimulation than those from small follicles except in progesterone production, for which FSH was equipotent). With the exception of forskolin, however, granulosa from large follicles showed little (oestradiol) or no stimulation (progesterone) with cAMP agonists. Under basal conditions, A23187 inhibited progesterone in all groups (P less than 0.05), and oestradiol production was reduced in granulosa cells from small follicles (P less than 0.05), unchanged in cells from medium follicles, and significantly stimulated in cells from large follicles. A23187 inhibited the enhanced production of both hormones after administration of cAMP agonists from cells of small and medium follicles (P less than 0.05), with inhibition significantly greater in cells of small follicles compared with medium. In cells from large follicles challenged with cAMP agonists, A23187 inhibited progesterone but stimulated oestradiol production; substitution of TPA (a protein kinase C stimulator) for A23187 gave identical results under basal or FSH-treated cultures of granulosa cells from small-, medium- or large-sized follicles. Our results suggest that TPA, A23187 and cAMP agonists modulate steroidogenesis differently in pig granulosa cells, depending on the stage of maturation of the follicle. Oestradiol production in granulosa cells from large preovulatory follicles may come under the stimulatory control of regulators of protein kinase C as in follicles near ovulation.     

Variety of mitochondrial shapes,sizes, and volumes inChlamydomonas reinhardii

Summary Mitochondria in cells ofChlamydomonas reinhardii, which at an intermediate stage of the vegetative cell cycle have been submitted to gametogenesis under dark and cold conditions, remain more or less unchanged with and without the addition of chloramphenicol. They exist in various number, shapes, and sizes and can be branched or unbranched as well as small or large. Giant mitochondria can be fused to a mitochondrial network, which, in contrast to the previously reported network (Grobe andArnold 1975), lies predominantly in the center of the cell. Mitochondrial volumes were revealed by means of morphometrical analyses from serial sections of four entire cells.     

The distribution, size and age compositions, and growth of the scallop Mizuhopecten yessoensis (Bivalvia: Pectinidae) in the northwestern Tatar Strait

The distribution patterns, size, age structure, and growth of the scallop Mizuhopecten yessoensis were studied in the northwest of the Tatar Strait, Sea of Japan. We determined that the northern boundary of the species range occurred in the region of Tabo Bay, at 51°37?? N. The distribution of the mollusk, depending on latitude, depth, substrate, and age, was determined. The maximum depth of M. yessoensis habitat is 138 meters, the maximum shell height is 200 mm, and the maximum age is 14 years. The differences in the growth rate of the Japanese scallop in different areas are discussed in relation to the conditions of its habitat in the northern part of its range.     

Variations in body size of the lancelet Branchiostoma belcheri at different depths in the Seto Inland Sea: effect of food supply on the growth rate

Variations in body size of the suspension-feeding lancelet Branchiostoma belcheri were examined from April 2001 to December 2001 at different water depths of 10-80 m. The lancelets were abundantly collected (220 indiv./dredge) at water depth of 10 m. The maximum size, ranging from 36.8 to 50.4 mm BL, decreased with increasing water depth. However, the minimum size of 7.4-7.8 mm BL, which corresponds to settling size, did not different with water depth. From seasonal changes in the length-frequency histograms, five cohorts were observed at every water depth. The lancelets grew to 44 mm BL at water depths of 10-20 m and to 34 mm BL at water depth of 80 m with four years of life span. Developmental stages of the gonads at an age of two years showed that no individuals had undeveloped gonads at water depth of 10 m, but 82% of them did at water depth of 80 m. The analysis of the stepwise multiple regressions of monthly growth rate on environmental variables showed that chlorophyll a was the best explanatory variable and showed a significant positive correlation with the growth of 1-2 years age groups. These results suggested that variations in the body length were mainly fluctuated by phytoplankton supply.     

Reproductive function state of the scallop Mizuhopecten yessoensis Jay from polluted areas of Peter the Great Bay, Sea of Japan

The morphology of gonads and development of offspring of the scallop Mizuhopecten yessoensis sampled from six stations in Peter the Great Bay (Sea of Japan) were studied. The retardation of gametogenesis, oocytes resorption, autolysis of spermatozoa and their phagocytosis were observed in the gonads of the scallops from polluted sites. The number of hermaphrodites was about 6% against 0.3–0.4% in the scallop populations from clean areas. In the offspring development, a decrease in fertilisation success,diminution in percent of normal trochophores, D-veligers, veligers, and retardation of larval growth were recorded. The scallop populations inhabiting polluted areas of Peter the Great Bay seem to be incapable of normal reproduction. Development of offspring was a more sensitive index of disturbance of the reproductive function than morphology of scallop gonads. Analysis of the offspring development of common species of marine invertebrates is suggested to be used as a sensitive indicator of adverse environmental conditions. This revised version was published online in August 2006 with corrections to the Cover Date.     

The structure and long-term dynamics of the communities of Arctica islandica (Bivalavia) in Rugozerskaya Guba of the White Sea

The age structure of a dense settlement of Arctica islandica (Bivalvia) near Vysokii Island (Rugozerskaya Guba (bay)) of the White Sea is described. The data collected by trawling in 2003, 2006–2007 and grab sampling in 2009–2011 are summarized. The A. islandica community in the Rugozerskaya Guba was first described in 1953–1959, but to date, no reliable quantitative estimates have been obtained and the community’s size structure was not studied. The size structure of this community was stable over the last eight years; the main part of the community was represented by individuals with a body weight of 3–10 g. It was revealed that the distribution of different A. islandica classes depends on the depth. The majority of the largest individuals were found in the shallowest parts of the study area (9–11 m); middle-size individuals were registered at depths of 9–14 m; and the smallest ones, at depths of 12–17 m.     

Size-dependent prey selection in piscivorous pikeperch Sander lucioperca and Volga pikeperch Sander volgensis shaped by bimodal prey size distribution

Prey size and species selection of pikeperch Sander lucioperca and Volga pikeperch Sander volgensis were investigated in relation to predator size in the shallow Lake Balaton, Hungary. Although their gape sizes were similar, S. lucioperca shifted to piscivory earlier and consumed fewer, but larger, prey than S. volgensis. Prey species preference of the two piscivores also differed. A bimodal prey size distribution resulted in a reclining sigmoid curve for the life span predator size to prey size relationship with inflexion points between 266 and 284 mm predator standard length (L(S) ) in S. lucioperca. In S. volgensis, as well as in S. lucioperca L(S) ≤ 350 mm, prey size increased monotonically with predator L(S) , following a power trend for all prey size variables. Prey depth to predator L(S) relationship varied significantly with prey species and prey number in both piscivores, and prey depth tended to be smaller in predators consuming more than one prey. Both predator species characteristically selected less active, benthic prey fishes in spite of their spiny fin rays, and small- and mid-sized predators selected for small prey. Relatively large prey were also eaten, however, especially by the smallest and largest S. lucioperca.     

Predation potential of the water bugs Sphaerodema rusticum on the sewage snails Physa acuta

The sewage snail Physa acuta is a serious threat to certain economic plants and to the purification plant of sewage works by rendering the biofilters ineffective. Various attempts are being made to control it. The efficacy of the predacious water bugs Sphaerodema rusticum was judged experimentally, in the laboratory in the potential control of P. acuta. It is revealed that, when supplied separately, the first, second and third instar and the adult S. rusticum did not attack P. acuta belonging to 3.1-8 mm, 5.1-8 mm, 7.1-8 mm and 相似文献   

Comparison of Cell Body Size and Oxidative Enzyme Activity in Motoneurons between the Cervical and Lumbar Segments in the Rat Spinal Cord after Spaceflight and Recovery

The cell body sizes and succinate dehydrogenase (SDH) activities of motoneurons in the dorsolateral region of the ventral horn at the cervical and lumbar segments in the rat spinal cord were determined following 9 days of spaceflight with or without 10 days of recovery on Earth. The motoneurons were divided into three types based on their cell body sizes; small-, medium-, and large-sized motoneurons. In control rats, there was no difference in the cell body size or SDH activity of small- and large-sized motoneurons between the cervical and lumbar segments. The SDH activity of medium-sized motoneurons in control rats was higher in the lumbar segment than in the cervical segment, while the cell body sizes of medium-sized motoneurons were identical. The SDH activity of medium-sized motoneurons in the lumbar segment decreased to a level similar to that in the cervical segment of control rats following spaceflight. In addition, the decreased SDH activity of medium-sized motoneurons persisted for at least 10 days of recovery on Earth. It is concluded that spaceflight selectively affects the SDH activity of medium-sized motoneurons in the lumbar segment of the spinal cord, which presumably innervate skeletal muscles having an antigravity function.     

Stimulatory effects of insulin-like growth factor 1 on expression of gonadotropin subunit genes and release of follicle-stimulating hormone and luteinizing hormone in masu salmon pituitary cells early in gametogenesis

Insulin-like growth factor-I (IGF-I) has been shown to be involved in pubertal activation of gonadotropin (GTH) secretion. The aim of this study was to determine if IGF-I directly stimulates synthesis and release of GTH at an early stage of gametogenesis. The effects of IGF-I on expression of genes encoding glycoprotein alpha (GPalpha), follicle-stimulating hormone (FSH) beta, and luteinizing hormone (LH) beta subunits and release of FSH and LH were examined using primary pituitary cells of masu salmon at three reproductive stages: early gametogenesis, maturing stage, and spawning. IGF-I alone or IGF-I + salmon GnRH (sGnRH) were added to the primary pituitary cell cultures. Amounts of GPalpha, FSHbeta, and LHbeta mRNAs were determined by real-time PCR. Plasma and medium levels of FSH and LH were determined by RIA. In males, IGF-I increased the amounts of all three subunit mRNAs early in gametogenesis in a dose-dependent manner, but not in the later stages. In females, IGF-I stimulated release of FSH and LH early in gametogenesis, whereas no stimulatory effects on the subunit mRNA levels were observed at any stage. IGF-I + sGnRH stimulated release of FSH and LH at all stages in both sexes, but had different effects on the subunit mRNA levels depending on subunit and stage. The present results suggest that IGF-I itself directly stimulates synthesis and release of GTH early in gametogenesis in masu salmon, possibly acting as a metabolic signal that triggers the onset of puberty.