三疣梭子蟹卵附着机制及相关形态学特征

Using histological methods and scanning electron microscopy, the structure of cement gland and formation of outer egg-membrane and egg-stalk of the swimming crab Portunus trituberculatus were studied to explain the mechanism of egg-attachment and function of the cement gland. Eggs adhered to the setae of pleopodal basipodite and endopodite for hatching followed by spawning but no egg attached on the setae of exopodite. The setae of pleopodal basipodite and endopodite were smooth for egg attachment while the setae of exopodite were branched and suitable for collecting and protecting eggs. Cement gland distributed along longitudinal axis of the pleopodal basipodite and endopodite under epithelia cells. Cells of the cement gland were elliptical and its size was about 50 times of the epithelium. Some glue secreted to the surface of the pleopod along the seta, while the other glue secreted to the surface of the pleopod by the channel which across the integument of the pleopod. The first spawned egg was transferred to the setae that were far from the pore, not attached to the setae of the pleopodal basipodite and endopodite near the genital pore. And the egg attachment became nearer and nearer to the pore with further spawning. Since the eggs to glide rather than roll, there was almost no glue on the contrary surface of the egg at first: and with further secretion, the whole surface was surrounded by glue. The thick part of glue formed one short bud during the glide of the egg and gradually developed into a full egg-stalk. On the other hand, the else glue developed into an outer egg-membrane, which was “trichromatic egg membrane” originally. Each egg attached to the setae of pleopodal basipodite and endopodite with its own egg-stalk. The egg-stalk was a plane strap at the formation stage and later it rolled into a rope shape, but it could be reverted to the former by outside force. Four types of egg attachment : an egg to a seta, an egg to several setae, several eggs to a seta and several eggs to several setae were discovered. In summary, the cement gland existed in the pleopod of the swimming crab and formed outer egg membrane and egg-stalk during the egg attachment [Acta Zoologica Sinica 50 (5) : 873 - 879, 2004].     

长毛对虾卵子皮层反应的研究

Morphology of the cortical reaction in the eggs of Penaeus penicillatus was studied with the light microscopy,scanning electron microscopy　and transmission electron microscopy. The cortical reaction is divided into four stages. These stages are unreacted stages, early stages, corona stages and dissipation stage. The cortical rods were released and formed a jelly coating around the surface of the egg. The jelly coating remained until the first cleavage had finished. In the end, the hatching membrane appeared around the egg. It is believed that these cortical reaction are responsible for the prevention of polyspermy by both a chemical and physical block and that also may establish a microenvironment inside a touch chorionic membrane for the developing embryo.     

Recognition of nestmate eggs in the ant Formicafusca is based on queen derived cues

Inclusive fitness benefits depend on recognizing the right individuals to interact with. Social insect nests protect themselves from non-kin intruders through nestmate recognition based on chemical cues. The recognition cues on adult individu- als are from a mixture of genetic and environmental sources, but the ontogeny and use of recognition cues on eggs has not been previously assessed. We studied recognition by workers of eggs that were either nestmates or non-nestmates, and the ontogeny of recognition cues on eggs in the ant Formica fusca, a species with precise egg recognition abilities. Workers were able to dis- criminate among freshly laid eggs with no nest derived cues on them, and the egg surface chemicals varied among nests in these eggs, suggesting that queen derived cues are used in nestmate recognition. The results are discussed in the light of their implica- tions on deceptive social parasite strategies and within colony conflicts     

Topography and functional information of plasma membrane

By using atomic force microscope (AFM), the topography and function of the plasmalemma surface of the isolated protoplasts from winter wheat mesophyll cells were observed, and compared with dead protoplasts induced by dehydrating stress. The observational results revealed that the plasma membrane of living protoplasts was in a state of polarization. Lipid layers of different cells and membrane areas exhibited distinct active states. The surfaces of plasma membranes were unequal, and were characterized of regionalisation. In addition, lattice structures were visualized in some regions of the membrane surface. These typical structures were assumed to be lipid molecular complexes, which were measured to be 15.8±0.09 nm in diameter and 1.9±0.3 nm in height. Both two-dimensional and three-dimensional imaging showed that the plasmalemma surfaces of winter wheat protoplasts were covered with numerous protruding particles. In order to determine the chemical nature of the protruding particles, living protoplasts were treated by proteolytic enzyme. Under the effect of enzyme, large particles became relatively looser, resulting that their width was increased and their height decreased. The results demonstrated that these particles were likely to be of protein nature. These protein particles at plasmalemma surface were different in size and unequal in distribution. The diameter of large protein particles ranged from 200 to 440 nm, with a central micropore, and the apparent height of them was found to vary from 12 to 40 nm. The diameter of mid-sized protein particles was between 40―60 nm, and a range of 1.8―5 nm was given for the apparent height of them. As for small protein particles, obtained values were 12―40 nm for their diameter and 0.7―2.2 nm for height. Some invaginated pits were also observed at the plasma membrane. They were formed by the endocytosis of protoplast. Distribution density of them at plasmalemma was about 16 pits per 15 μm2. According to their size, we classified the invaginated pits into two types―larger pits measuring 139 nm in diameter and 7.2 nm in depth, and smaller pits measuring 96 nm in diameter and 2.3 nm in depth. On dehydration-induced dead pro-toplasts, the degree of polarization of plasma membranes decreased. Lipid molecular layers appeared relatively smooth, and the quantity of integral proteins reduced a lot. Invaginated pits were still de-tectable at the membrane surface, but due to dehydration-induced protoplast contraction, the orifice diameter of pits reduced, and their depth increased. Larger pits averagely measuring 47.4 nm in di-ameter and 31.9 nm in depth, and smaller pits measuring 26.5 nm in diameter and 43 nm in depth at average. The measured thickness of plasma membranes of mesophyll cells from winter wheat examined by AFM was 6.6―9.8 nm, thicker in regions covered with proteins.     

Rice root growth in relation to size,quantity, and rigidity of pores

Summary Experiments were conducted to study the influence of porosity, pore size and pore rigidity of sands, developed in tubes and culture vessels, on rice root growth. The root growth parameters included: number of penetrating roots, length, length of radicle above sand surface, depth of penetration, diameter near the tip and base, volume and fresh weight. The relationships between porosity, pore size of sand and root growth parameters were found to be nonlinear. A porosity of 51.6% was most favourable to rice root growth and penetration. The root tips could expand an average macropore size of 75 μ for their penetration. In fine sand (150−50 μ), though the pore size was very narrow, roots were able to penetrate because of low rigidity of pores. The increasing pore rigidity of sand abridged root penetration. The critical rigidity in terms of penetration pressure was measured to be 435 kg cm⁻² with coarse sand (400−320 μ). The rigidity of pore structure depended largely on particle size and porosity of sands. The penetration pressure was reduced with decrease in particle size of sand. Contribution from the Department of Agricultural Engineering, Indian Institute of Technology, Kharagpur, West Bengal, India. Junior Soil Physicist and formerly Assistant Professor of Soil Science (now Head and Professor of Soil Science, U.P. Agricultural University, Pantnagar, Nainital, U.P., India), Agricultural Engineering Department, Indian Institute of Technology, Kharagpur, West Bengal, India.     

Expression of. Arabidopsis tryptophan biosynthetic pathway genes: effect of the 5' coding region of phosphoribosylanthranilate isomerase gene

There are three non-allelic isogenes encoding phosphoribosylanthranilate isomerase (PAI) in Arabidopsis thaliana. The expression plasmids were constructed by fusion of the GUS reporter gene to the three PAI promoters with or without the 5' region encoding PAI N-terminal polypeptides and transferred into Arabidopsis plants by Agrobacterium tumefaciens. Analysis of GUS activity revealed that the PAI 5' coding region was necessary for high expression of GUS activity. GUS activity in transgenic plants transformed with the expression plasmids containing the 5' coding region of PAI1 or PAI3 was 60—100-fold higher than that without the corresponding 5' region. However, the effect of 5' coding region of PAI2 gene on the GUS activity was very small (only about 1 time difference). The GUS histochemical staining showed a similar result as revealed by GUS activity assay. It was expressed in the mesophyll cells and guard cells, but not in the epidermic cells, indicating that the N-terminal polypeptides encoded by t     

蟋蟀精子表面LCA及ConA结合糖复合物的分布变化

LCA and ConA-binding glycoconjugates on cricket (Teleogryllus emma) sperm surface were detected with fluorescence microscope after FITC labelling for better understanding of the distribution of glycoconjugates during spermatogenesis and spermiogenesis. FITC-LCA and FITC-ConA were bound on the spermatocytes, and their distribution changes in the process of spermiogenesis were observed .In the testis sperm, FITC-LCA and FITC-ConA were mainly bound on the head and neck region. That is different from the mark pattern of spermatophore sperm, in which the nucleus, neck region and front of the tail showed obvious fluorescence mark, especially the acrosome complex and neck region exhibited stronger mark. The mark patterns of FITC-LCA and FITC-ConA were similar,though the former was distinctly clearer than the latter. But a little difference still exists in both of them. For example in the ninth stage of spermatid, FITC-LCA mark is located on the spermatid head and neck region, and FITC-ConA mark on the spermatid head, neck and front of the tail region. When fixed germ cells were treated with PBS instead of lectin solution, or fixed cells were incubated with lectin solution, which have been treated with 0.1 mol/L specific sugar inhibitor, i.e.α-D-mannose for FITC-LCA and FITC-ConA, and α-D-glucose for FITC-ConA, no mark was observed on the cells. Those results indicate that FITC-LCA conjugated glycoconjugates has the α-D- mannose residue, and FITC-ConA conjugated glycoconjugates has the α-D-mannose and α-D-glucose residue. The investigations show that the changes in glycoconjugates distribution of cricket sperm is similar to those of other insects and mammals. The evidence exhibit that a common rule of the glycoconjugates distribution on the sperm surface is followed by most of animal sperm which may relate to the function of sperm physiology.     

Experiment about Drag Reduction of Bionic Non-smooth Surface in Low Speed Wind Tunnel

The body surface of some organisms has non-smooth structure, which is related to drag reduction in moving fluid. To imitate these structures, models with a non-smooth surface were made. In order to find a relationship between drag reduction and the non-smooth surface, an orthogonal design test was employed in a low speed wind tunnel. Six factors likely to influence drag reduction were considered, and each factor tested at three levels. The six factors were the configuration, diameter/bottom width, height/depth, distribution, the arrangement of the rough structures on the experimental model and the wind speed. It was shown that the non-smooth surface causes drag reduction and the distribution of non-smooth structures on the model, and wind speed, are the predominant factors affecting drag reduction. Using analysis of variance, the optimal combination and levels were obtained, which were a wind speed of 44 m/s, distribution of the non-smooth structure on the tail of the experimental model, the configuratio     

Effects of Biomimetic Surface Designs on Furrow Opener Performance

The effects of biomimetic designs of tine furrow opener surface on equivalent pressure and pressure in the direction ofmotion on opener surface against soil were studied by finite element method (FEM) simulation and the effects of these designson tool force and power requirements were examined experimentally.Geometrical structures of the cuticle surfaces of dungbeetle (Copris ochus Motschulsky) were examined by stereoscopy.The structures of the cuticle surfaces and Ultra High Mo-lecular Weight Polyethylene (UHMWPE) material were modeled on surface of tine furrow opener as biomimetic designs.Sevenfurrow openers were analyzed in ANSYS program (a FEM simulation software).The biomimetic furrow opener surfaces withUHMWPE structures were found to have lower equivalent pressure and pressure in the direction of motion as compared to theconventional surface and to the biomimetic surfaces with textured steel-35 structures.It was found that the tool force and powerwere increased with the cutting depth and operating speed and the biomimetic furrow opener with UHMWPE tubular sectionridges showed the lowest resistance and power requirement against soil..     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.