Stomata actively regulate internal aeration of the sacred lotus Nelumbo nucifera

The sacred lotus Nelumbo nucifera (Gaertn.) possesses a complex system of gas canals that channel pressurized air from its leaves, down through its petioles and rhizomes, before venting this air back to the atmosphere through large stomata found in the centre of every lotus leaf. These central plate stomata (CPS) lie over a gas canal junction that connects with two‐thirds of the gas canals within the leaf blade and with the larger of two discrete pairs of gas canals within the petiole that join with those in the rhizome. It is hypothesized that the lotus actively regulates the pressure, direction and rate of airflow within its gas canals by opening and closing these stomata. Impression casting the CPS reveal that they are open in the morning, close at midday and reopen in the afternoon. The periodic closure of the CPS during the day coincides with a temporary reversal in airflow direction within the petiolar gas canals. Experiments show that the conductance of the CPS decreases in response to increasing light level. This behaviour ventilates the rhizome and possibly directs benthic CO₂ towards photosynthesis in the leaves. These results demonstrate a novel function for stomata: the active regulation of convective airflow.     

Drosophila Lin-7 is a component of the Crumbs complex in epithelia and photoreceptor cells and prevents light-induced retinal degeneration

The Drosophila Crumbs protein complex is required to maintain epithelial cell polarity in the embryo, to ensure proper morphogenesis of photoreceptor cells and to prevent light-dependent retinal degeneration. In Drosophila, the core components of the complex are the transmembrane protein Crumbs, the membrane-associated guanylate kinase (MAGUK) Stardust and the scaffolding protein DPATJ. The composition of the complex and some of its functions are conserved in mammalian epithelial and photoreceptor cells. Here, we report that Drosophila Lin-7, a scaffolding protein with one Lin-2/Lin-7 (L27) domain and one PSD-95/Dlg/ZO-1 (PDZ) domain, is associated with the Crumbs complex in the subapical region of embryonic and follicle epithelia and at the stalk membrane of adult photoreceptor cells. DLin-7 loss-of-function mutants are viable and fertile. While DLin-7 localization depends on Crumbs, neither Crumbs, Stardust nor DPATJ require DLin-7 for proper accumulation in the subapical region. Unlike other components of the Crumbs complex, DLin-7 is also enriched in the first optic ganglion, the lamina, where it co-localizes with Discs large, another member of the MAGUK family. In contrast to crumbs mutant photoreceptor cells, those mutant for DLin-7 do not display any morphogenetic abnormalities. Similar to crumbs mutant eyes, however, DLin-7 mutant photoreceptors undergo progressive, light-dependent degeneration. These results support the previous conclusions that the function of the Crumbs complex in cell survival is independent from its function in photoreceptor morphogenesis.     

圈养华南虎食物通过消化管时间的初步测定

采用苹果皮作标记物 ,对 4只圈养成年健康华南虎的食物通过消化管的时间进行试验性测定 ,结果平均值为 18 36± 3 5 8h (13 83～ 2 2 5 7h) ,其中 9∶30投喂的为 2 1 97± 0 74h ,16∶4 0投喂的为 15 2 0± 0 87h ,牛肉、混合饲料间和虎个体间差异均不显著。     

Ultrastructure of the Alimentary Canal in Five-Month-Old Pentactulae of the Holothurian Eupentacta fraudatrix

Five-month-old pentactulae (juveniles) of the holothurian Eupentacta fraudatrixpossess a well-developed alimentary canal comprising an esophagus, a stomach, an intestine, and a rectum. The intestine in turn consists of five parts. The esophagus, stomach, and rectum are lined with a cuticular epithelium. The intestinal lining lacks a cuticle and is composed of mainly polyfunctional vesicular enterocytes. Granular enterocytes are less abundant; their cytoplasm contains electron-dense granules, which are probably zymogenic. The gut connective tissue consists of electron-lucent ground substance with collagen fibers and embedded coelomocytes. The gut mesothelium is composed of myoepithelial and peritoneal cells and contains the neurons of the hyponeural nerve plexus.     

管壳缝类硅藻中国新记录属种——非洲南氏藻

利用光学和电子显微镜对采自黄海水域的1个管壳缝类硅藻——非洲南氏藻进行了形态学研究,并对其地理分布进行了讨论.结果表明:(1)该种壳体带面呈矩形,壳面窄椭圆形,具有钝圆的末端.(2)壳缝居中,由两条等长的分支组成.(3)管壳缝由复杂、接合的肋突支撑,但无龙骨.(4)每条线纹仅有1个孔纹,壳套上最多有1列孔纹.(5)目前...     

编码日本血吸虫抱雌沟蛋白及肌动蛋白的基因性别间的表达差异性

研究了所克隆的日本血吸虫两个基因的性别间的表达差异性。分别将所克隆到的编码日本血吸虫抱雌沟蛋白的cDNA(SjGCP1)和肌动蛋白的cDNA(SjAct)制成DNA探针,利用Southern blotting,Northern blotting和斑点印迹法对其相应基因性别间的表达差异性进行了研究。结果显示,日本血吸虫抱雌沟蛋白的基因在雄虫中转录而雌虫中不转录,血吸虫肌动蛋白基因在雄虫中转录量高于雌虫,表现出转录量的差异。证明这两个基因转录具有性别间的表达差异性。     

门齿孔位置在中国古人类化石与现代人群的表现及其演化意义

魏敦瑞在研究周口店北京直立人化石时发现,位于上颌骨硬腭表面的门齿孔位置在周口店标本靠后,而在现代人靠近齿槽。此后,门齿孔位置作为具有演化意义的形态特征被用于古人类学研究。迄今,对门齿孔位置在中国古人类化石表现的专门研究仅有周口店一件标本,而在现代中国人的数据尚属空白。鉴于此,本文对门齿孔位置在中国古人类化石以及现代中国人标本进行了观察、测量和数据统计。在此基础上,结合世界其他地区古人类数据资料,本文对门齿孔位置在中国古人类化石的表现特点及其演化意义进行了探讨。本研究发现,从更新世早期到更新世晚期,门齿孔位置在中国古人类呈现由后向前的总体变化趋势。更新世早期和中期直立人(郧县曲远河口、周口店)的门齿孔位置都比较靠后;中更新世晚期的部分中国古人类(大荔、长阳、华龙洞)的门齿孔位置前移,并与现代人接近,而金牛山和巢县门齿孔位置比较靠后,位于直立人范围;在更新世晚期,所有中国古人类都比较靠前,位于现代人变异范围。本文对现代人标本的观测显示,门齿孔位置在现代中国人比较靠前。现代人门齿孔大小及形态存在较大变异,这种表现特点在一定程度上影响对门齿孔位置及演化意义的判定。几乎全部现代人标本门齿孔前缘呈...     

Ultrastructure of the stylar canal cells ofCitrus limon (Rutaceae)

The ultrastructure of the canal cells and the canal filling substance ofCitrus limon have been studied. At maturity the canal cells are very rich in cytoplasm. Their inner tangential walls lining the canal are much thickened and formed by two layers: the outer corresponds to the original wall, the inner is formed by subsequent deposition of abundant materials of different origin. This thickening occurs at the same time as the filling of the stylar canal. Both events are paralleled by considerable dictyosomic activity, the formation of a large amount of rough endoplasmic reticulum, and the incorporation of small cytoplasmic masses into the cell wall, due to plasmalemma evaginations. — The material in the stylar canal has a heterogeneous ultrastructure aspect and consists of polysaccharides, proteins and lipids; it presumably provides nutrients for the growing pollen tubes.Research performed under CNR program Biology of Reproduction.     

Immnunohistochemical detection of phthalate esters in the alimentary canal of Tilapia spp.

An examination of the occurrence and distribution of phthalate esters in the alimentary canal of a polyhybrid of Tilapia gave evidence of different and selective patterns of distribution in the organ tissues: the phthalate esters were shown to be concentrated in the stomach and anterior intestine. The restricted distribution of phthalate esters can have implications for the physiology of the digestive system. The phthalates, stored in the oxyntic cells of the gastric tubular glands, probably interfere with the digestive process. The strategic location of the enterocytes in the anterior intestine implies that they can hamper the reabsorption of digestion products. The endocrine disrupting effects known for these chemicals are probably related to the absorption of them via the alimentary canal.     

<Emphasis Type="Italic">Afuni</Emphasis>, a novel transforming growth factor-β gene is involved in arm regeneration by the brittle star <Emphasis Type="Italic">Amphiura filiformis</Emphasis>

The bone morphogenetic proteins (BMPs) are a family of the transforming growth factor- (TGF-) superfamily that perform multiple roles during vertebrate and invertebrate development. Here, we report the molecular cloning of a novel BMP from regenerating arms of the ophiuroid Amphiura filiformis. The theoretically translated amino acid sequence of this novel BMP has high similarity to that of the sea urchin BMP univin. This novel BMP has been named afuni. Whole-mount in situ hybridisation implicates afuni in arm regeneration. Expression occurs in distinct proximal and distal regions of late regenerates (3- and 5-week postablation). These sites are at different stages of regeneration, suggesting multiple roles for this gene in adult arm development. Cellular expression of this gene occurs in migratory cells within the radial water canal (RWC) of regenerating and nonregenerating arms. These migrating coelomocytes suggest a key role for the coelomic RWC as a source of the cellular material for use in arm regeneration by A. filiformis.