干出和沉水不同条件下羊栖菜光合作用碳源获得机制比较

经济海洋褐藻羊栖菜(Hizikia fusiforme(Harv.)Okamura)低潮时常常周期性地暴露于空气中.为了认识这种海藻在潮汐循环背景下的光合特征,对其在高潮沉水和低潮干出不同条件下的光合作用碳素获得机制进行了比较.沉水时,羊栖菜主要利用海水中HCO3-作为外源无机碳源驱动光合作用;而在干出条件下,其光合作用的主要碳源为空气中的CO2.在这两种不同环境条件下,光合作用与pH值的关系不同:沉水状态时,羊栖菜在高pH值(10.0)下光合活性很弱;而在干出条件下,羊栖菜在高pH值时仍有较高的光合活性.然而,光合作用无论是在沉水还是在干出条件下,对外源碳源的获得都表现出对胞外碳酸酐酶(CA)强烈的依赖性,并且其光合速率都受周围环境中无机碳源水平的限制.此外,在沉水和干出两种环境条件下,羊栖菜光合作用都表现出对氧气的敏感性.这表明,在羊栖菜中,依赖胞外CA的碳源获得机制不能使细胞内CO2浓度提高到阻碍其光呼吸的程度.增加空气中或海水中无机碳的浓度,能促进羊栖菜的光合作用,进而增加这种海藻的水产养殖产量.     

经济海藻红毛菜原位光合作用日变化

利用光合气体交换和叶绿素a荧光技术测定了原位沉水和干出条件下红毛菜光合作用的日变化,结果显示与沉水藻体相比,中午干出藻体光合速率、光系统II最大光化学效率(Fv/Fm)、实际光化学效率(ΦPSⅡ)、光化学淬灭系数(qP),光响应曲线初始斜率(ɑETR)和相对电子传递速率(rETR)值下降更明显。干出藻体重新入水后,其叶绿素a荧光参数在两个小时内可以完全恢复到沉水藻体的水平。红毛菜叶绿素a、类胡萝卜素、藻红蛋白的含量在一天中并没有出现明显变化。以上结果表明红毛菜日生长在中午要经历光抑制过程,干出状态下光抑制更严重;干出和沉水藻体光合速率都可以在傍晚得以恢复;红毛菜光系统II反应中心可以通过增加热耗散和降低光合电子传递速率等策略来应对光抑制。     

干出和沉水不同条件下羊栖菜光合作用碳源获得机制比较(英文)

经济海洋褐藻羊栖菜(Hizikia fusiforme(Harv.)Okamura)低潮时常常周期性地暴露于空气中。为了认识这种海藻在潮汐循环背景下的光合特征,对其在高潮沉水和低潮干出不同条件下的光合作用碳素获得机制进行了比较。沉水时,羊栖菜主要利用海水中HCO_3~-作为外源无机碳源驱动光合作用;而在干出条件下,其光合作用的主要碳源为空气中的CO_2。在这两种不同环境条件下,光合作用与pH值的关系不同:沉水状态时,羊栖菜在高pH值(10.0)下光合活性很弱;而在干出条件下,羊栖菜在高pH值时仍有较高的光合活性。然而,光合作用无论是在沉水还是在干出条件下,对外源碳源的获得都表现出对胞外碳酸酐酶(CA)强烈的依赖性,并且其光合速率都受周围环境中无机碳源水平的限制。此外,在沉水和干出两种环境条件下,羊栖菜光合作用都表现出对氧气的敏感性。这表明,在羊栖菜中,依赖胞外CA的碳源获得机制不能使细胞内CO_2浓度提高到阻碍其光呼吸的程度。增加空气中或海水中无机碳的浓度,能促进羊栖菜的光合作用,进而增加这种海藻的水产养殖产量。     

瓦氏马尾藻有性繁殖和幼孢子体发育的形态学观察

通过采集浙江舟山枸杞岛海域野生瓦氏马尾藻（Sargassum vachellianum）进行培养,研究瓦氏马尾藻的繁殖季节、温度、生殖托的发育、卵子的成熟和排放、假根的生长以及幼孢子体的前期发育。实验结果表明:位于浙江舟山枸杞岛的瓦氏马尾藻繁殖季节为4-6月,繁殖高峰期水温为18-21℃。雌、雄生殖托早期无明显差异,中后期差异变大,瓦氏马尾藻藻体在排放完卵子和精子后开始衰败。瓦氏马尾藻卵子属于8核1卵型,受精过程在雌性生殖托表面发生,受精后开始从雌性生殖托脱落,部分存在挂托分裂现象。在幼孢子体分裂前期,假根生长速度大于幼孢子体本身的生长速度。幼孢子体先长成一片叶子,再进行第二片叶子的发育,逐渐分化出主茎和初生分枝。     

羊草种群生物量生殖分配的初步研究

对羊草种群生物量生殖分配的研究表明,在生殖生长过程中,种群用于根茎和营养生长的生物量生殖分配占有绝对优势比例,而用于有性生殖的生物量生殖分配比例较小,在10%以下。在羊草种群构件生物量生殖分配中,根茎和营养枝的叶占有较大比例(20%～40%),而用于有性繁殖体种子生产的比例很小,在1.5%以下。对有性繁殖的小比例投资是导致羊草种群有性繁殖体种子产量低的重要原因.     

黄海太平角鼠尾藻有性繁殖分配

以位于黄海的青岛太平角自然生长的鼠尾藻为对象,研究其有性繁殖分配动态及相关环境因子.结果表明:鼠尾藻于6月初开始进入有性繁殖期,于7月中旬海水温度22℃左右达到繁殖高峰,7月19日平均繁殖分配(RA)达76.7%,8月末有性繁殖结束.鼠尾藻繁殖分配与平均分枝长度呈显著线性相关(r=0.855,P<0.01).长度在10cm以下的藻体在整个繁殖期内的RA较低,而长度在10cm以上的藻体在成熟高峰期的RA在70.0%以上.析因方差分析表明,潮位和浪冲击度均对鼠尾藻有性繁殖分配有显著影响(潮位:F=175.62,P<0.001,浪冲击度:F=95.35,P<0.01),且二者之间存在交互作用(F=9.14,P<0.05).其对RA的影响大小依次为潮位>浪冲击度>潮位×浪冲击度.     

地钱生殖托形态结构新观察及其对有性生殖的适应

用显微观察技术对苔类植物地钱（Marchantia polymorpha）生殖托的形态结构进行了研究,本研究的新观察包括：（1）生殖托具有明显的背腹分化,被认为是叶状体为适应有性生殖而高度特化的直立枝;（2）雌托盘的9～11个指状裂瓣中边缘两个稍不同,除了两个边缘裂瓣外的其他裂瓣间具雌苞。托柄具有背腹之分,雌托柄背面具光合组织,并向两侧扩展形成纵沟,雌托柄的腹面具2条被鳞片重叠覆盖相互平行的纵沟,内具假根;（3）与雌托柄不同,雄托柄外观平滑,背面无光合组织及纵沟。观察发现,伞状的雌托能滞留水分,并沿雌托柄的纵沟缓慢释放连续的水流,游动精子沿着纵沟内的水流到达雌托下面的颈卵器。上述观察表明地钱生殖托的结构是对有性生殖的一种适应,这有助于我们理解地钱受精作用的机理。     

鼠尾藻生长与生殖的权衡

2009年7月初至2009年9月中旬对烟台长岛县望福礁附近水域鼠尾藻(Sargassum thunbergii)进行了生态学调查。实验设立固定采样地点通过随机采样以及现场标记测量的方法观测了鼠尾藻的生长与生殖情况。结果表明:(1)鼠尾藻生殖始于7月初,8月初为高峰期,此间87%的藻体产生生殖托;(2)藻体长度对成熟比例和生殖力均有显著的影响,藻体成熟具有大小依赖性;(3)营养组织生物量大的鼠尾藻群体生殖组织生物量也相对较大,生殖期间营养组织生长和生殖组织生长呈异速关系;(4)成熟藻体在有性生殖高峰期过后,生长率下降,而始终未成熟的藻体则持续生长(生长率0)。以上结果表明,在鼠尾藻的生活史中存在着生长与生殖的权衡。     

“袖珍标本”的制作方法

现以地钱为例介绍如下: 雌株当地钱雌株的雌托下面的颈卵器(为黄色倒挂钟形)长出时,轻轻地将整株从土中挖出,清水洗净,浸泡于饱和小苏打溶液中约24小时取出,清水冲洗,稍干,即可置于载玻片上,注意用镊子将植株的叶状体、假根、托柄及指状雌托伸展开,盖上另一载玻片(不要挤压),两头用线捆扎或橡皮膏固定即可。雄株制做方法同上。需要注意的是,除     

武夷山的石地钱

石地钱(Reboulia hemisphaerica)属苔纲地钱目石地钱科石地钱属植物,多生长在林下石面较干燥的土层上。其叶状体(配子体)扁平带状,二叉分枝,腹面沿中肋有一条假根槽,生有许多假根,槽的两侧生有紫红色鳞片。雌生殖托半球形,绿色分瓣,     

Y-chromosome Data and Tribal Affiliations of Allenopithecus and Miopithecus

The phylogeny of Old World monkeys has remained unresolved in part because of a lack of resolution in the Cercopithecinae. Competing morphological hypotheses have had Allen's swamp monkey (Allenopithecus nigroviridis) and the talapoins (Miopithecus spp.) as basal branches of either the tribe Cercopithecini or the tribe Papionini. Previous molecular analyses have not adequately addressed the issue. To better understand the evolutionary history of these primates, we sequenced and subjected to phylogenetic analysis 3.1 kb of 2 loci (TSPY and SRY) from the non-recombining portion of the Y-chromosome. Individuals from the genera Allenopithecus, Miopithecus, Erythrocebus, Chlorocebus, and Cercopithecus were surveyed and their sequences compared with those previously published for the Papionini and Colobinae. The results suggest Allenopithecus and Miopithecus are more closely related to the Cercopithecini than Papionini. Our data also support the hypothesis that within the Cercopithecini, Erythrocebus and Chlorocebus share a close evolutionary relationship, distinct from the other members of the tribe.     

Nystatin and killer toxin sensitivity of free and immobilizedSaccharomyces cerevisiae

The inhibitory effect of nystatin and killer toxin on the growth of free and covalently-immobilizedSaccharomyces cerevisiae cells was studied. The resistance of immobilized cells to both agents was accompanied by increased amounts of phospholipids and sterols. The possible relationship between these changes in the membrane composition and the transduction of a signal across the cytoplasmic membrane is discussed.     

Molecular identification and differentiation of Brevibacterium species and strains

Amplified ribosomal DNA restriction enzyme analysis (ARDRA), pulsed field gel electrophoresis (PFGE) and ribotyping were used to differentiate among 24 strains of Brevibacterium linens, Brevibacterium casei and Brevibacterium epidermidis obtained from type culture collections or isolated from various smear ripened cheeses. ARDRA was applied to the 16S rDNA. B. linens was shown to be a quite heterogenic group with 2 to at least 4 copies of rrn operons per strain with aberrant nucleotide sequences. AccI gave genus specific restriction patterns and was used to separate Brevibacterium from Corynebacterium species. The expected species specificity of TaqI applied to B. linens type culture strains, but not to all strains isolated from cheese. By AvaI restriction, B. casei and B. linens were differentiated from B. epidermidis and the orange pigmented Arthrobacter casei, a new species of coryneform bacteria; by XmnI restriction, B. linens and B. epidermidis were differentiated from B. casei. One of 4 B. linens genotypes could not be distinguished from B. casei by this method. Here, the typical orange B. linens pigments were used for classification, which was confirmed by partial sequencing of the 16S rDNA.     

Evaluation of antiprotozoal and antimycobacterial activities of the resin glycosides and the other metabolites of Scrophularia cryptophila

Resin glycosides are secondary metabolites exclusive to the convolvulaceous plants. In this study, crypthophilic acids A–C (1–3), the first resin glycosides occurring in another family (Scrophulariaceae), and the other constituents of Scrophularia cryptophila were examined for in vitro antiprotozoal and antimycobacterial potentials. Except for crypthophilic acid B (2), all tested compounds exhibited growth-inhibitory effect against Trypanosoma brucei rhodesiense, with l-tryptophan (6) and buddlejasaponin III (7) being the most potent ones (IC₅₀'s 4.1 and 9.7 μg/ml). In contrast, the activity towards Trypanosoma cruzi was poor, and only crypthophilic acid C (3), 6 and 7 were trypanocidal at concentrations above 40 μg/ml. With the exception of 2 and 6, all compounds were active against Leishmania donovani. Harpagide (4) and 3 emerged as the best leishmanicidal agents (IC₅₀'s 2.0 and 5.8 μg/ml). Only compounds 3, 6 and 7 showed antimalarial activity against Plasmodium falciparum with IC₅₀ values of 4.2, 16.6 and 22.4 μg/ml. Overall the best and broadest spectrum activity was presented by compounds 3 and 7, as they inhibited all four parasitic protozoa. None of the isolates had significant activity against Mycobacterium tuberculosis (MICs >100 μg/ml) or were toxic towards mammalian (L6) cells. This is the first report of antiprotozoal activity for natural resin glycosides, as well as for harpagide (4), acetylharpagide (5), tryptophan (6) and buddlejasaponin III (7).     

Theoretical Study of Antagonists and Inhibitors of Mammalian Adenosine Deaminase: I. Adenosine and Its Aza- and Deazaanalogues

Aza- and deazaanalogues of adenosine, including their 1-protonated forms (except for that of 1-deazaadenosine), were studied by computer computation to find a relationship between their molecular structures and substrate properties for the mammalian adenosine deaminase. The atomic charge distribution and maps of the electrostatic potential around their van der Waals molecular surface were calculated for these compounds using the ab initio STO-3G method. The conformational studies are carried out by the MM⁺ method of molecular mechanics. The mechanism that determines the substrate selectivity of mammalian adenosine deaminase is discussed.     

Effects of carbon concentration and carbon to nitrogen ratio on the growth and sporulation of several biocontrol fungi

Effects of carbon concentration and carbon to nitrogen (C:N) ratio on six biocontrol fungal strains are reported in this paper. All fungal strains had extensive growth on the media supplemented with 6–12 g l⁻¹ carbon and C:N ratios from 10:1 to 80:1, and differed in nutrient requirements for sporulation. Except for the two strains of Paecilomyces lilacinus, all selected fungi attained the highest spore yields at a C:N ratio of 160:1 when the carbon concentration was 12 g l⁻¹ for Metarhizium anisopliae SQZ-1-21, 6 g l⁻¹ for M. anisopliae RS-4-1 and Trichoderma viride TV-1, and 8 g l⁻¹ for Lecanicillium lecanii CA-1-G. The optimal conditions for P. lilacinus sporulation were 8 g l⁻¹ carbon with a C:N ratio of 10:1 for M-14 and 12 g l⁻¹ carbon with a C:N ratio of 20:1 for IPC-P, respectively. The results indicated that the influence of carbon concentration and C:N ratio on fungal growth and sporulation is strain dependent; therefore, consideration for the complexity of nutrient requirements is essential for improving yields of fungal biocontrol agents.     

Pericarp structure and phylogeny of theLamiaceae-Verbenaceae-complex

Pericarp structure was investigated in 158 species of the familiesLamiaceae andVerbenaceae. Data from 221 out of 262 genera ofLamiaceae s.l. and a few ofVerbenaceae s.str. were collected in a table. A cladistic analysis was performed on the basis of pericarp characters only. The abandonment of subfam.Pogostemonoideae as a taxonomic unit is considered. Examples of groups given additional support by similarities in pericarp characters are: (1) the gynobasic-styled labiates (subfamiliesPogostemonoideae, Lamioideae, Nepetoideae); (2) aLamioideae-Pogostemonoideae-group; (3)Nepetoideae; (4) aWestringia-Hemigenia-Hemiandra-Microcorys group (in subfam.Chloranthoideae); (5) aLepechinia-Chaunostoma-group (inNepetoideae); (6) aPrunella-Cleonia-group (inNepetoideae).     

The hernandez and fernandez genes of Drosophila specify eye and antenna

The formation of different structures in Drosophila depends on the combined activities of selector genes and signaling pathways. For instance, the antenna requires the selector gene homothorax, which distinguishes between the leg and the antenna and can specify distal antenna if expressed ectopically. Similarly, the eye is formed by a group of "eye-specifying" genes, among them eyeless, which can direct eye development ectopically. We report here the characterization of the hernandez and fernandez genes, expressed in the antennal and eye primordia of the eye-antenna imaginal disc. The predicted proteins encoded by these two genes have 27% common amino acids and include a Pipsqueak domain. Reduced expression of either hernandez or fernandez mildly affects antenna and eye development, while the inactivation of both genes partially transforms distal antenna into leg. Ectopic expression of either of the two genes results in two different phenotypes: it can form distal antenna, activating genes like homothorax, spineless, and spalt, and it can promote eye development and activates eyeless. Reciprocally, eyeless can induce hernandez and fernandez expression, and homothorax and spineless can activate both hernandez and fernandez when ectopically expressed. The formation of eye by these genes seems to require Notch signaling, since the induction of ectopic eyes and the activation of eyeless by the hernandez gene are suppressed when the Notch function is compromised. Our results show that the hernandez and fernandez genes are required for antennal and eye development and are also able to specify eye or antenna ectopically.     

Origin and development of Tool-making behavior in Africa and Asia

Around two-and-a-half million years ago, some hominid populations in Africa began to modify stones and bones in a manner that can be recognized by prehistorians as artifacts, and, by definition, produced the earliest identifiable archaeological record. It is likely that earlier hominid groups also may have had relatively rich tool-using behavioral repertoires similar to that seen in modern chimpanzees (McGrew, 1992), such tools may have been made of perishable materials or minimally modified and thus difficult to identify. This review will focus on the earliest archaeological traces and the spread of hominids out of Africa and into Eurasia.     

Spatial and temporal patterns of morel fruiting

The biotic and abiotic factors conditioning morel fruit body production are incompletely known. We examined spatial and temporal patterns of Morchella esculenta fruiting over five years in a wooded site in Missouri, USA. Fruiting onset was inversely correlated with spring air and soil temperatures, whereas abundance was positively correlated with rain events (>10 mm) during the 30 d preceding fruiting. The two years with the greatest fruiting had the shortest fruiting seasons (6–7 d). Fruiting season length was positively correlated with soil warming, suggesting that a narrow range of optimum soil temperatures favour the explosive production of fruit bodies. All woody stems of at least 1 cm diam were mapped and stem diameter and crown condition were noted. Morel fruit bodies were significantly closer to stems of Carya spp., Tilia americana and Ulmus americana than predicted by the frequencies of these woody species or their contribution to the total basal area on the site. Although intra-annual clustering of fruit bodies was often observed, inter-annual clustering was not. The spatial pattern of M. esculenta fruiting appears to be associated with vegetation pattern, whereas the onset and abundance of fruiting are determined by the interaction of spring temperatures with availability of supporting precipitation.