Testing hybridization hypotheses and evaluating the evolutionary potential of hybrids in mangrove plant species

Natural hybridization is of marked importance from global to local biological diversity. In mangroves, species ranges overlap extensively with one another and species share a long overlap of flowering time. Although hybridization has been suggested, patterns of hybridization and the evolutionary potential of hybrids are not yet fully understood. This study provides molecular evidence for the parental origins and status of hybrids in the dominant mangrove genus Rhizophora based on comparisons of chloroplast and nuclear phylogenies and estimations of genetic relatedness and structure from inter‐simple sequence repeat (ISSR) markers. Phylogenetic analyses indicate that almost all species can act as maternal parents to hybrids and that hybridization can be bidirectional. Bayesian analyses indicate that hybrids are simple F₁s, and no trace of backcrossing was detected within populations. Hybridization, for the most part, occurs almost only locally and dispersal of hybrid individuals is limited beyond the hybrid sites.     

Leaf anatomical properties in relation to differences in mesophyll conductance to CO2 and photosynthesis in two related Mediterranean Abies species

Abies alba and Abies pinsapo are closely related species with the same ribulose 1·5‐bisphosphate carboxylase/oxygenase (Rubisco) large subunit (rbcL) but contrasting hydraulic traits and mesophyll structure occurring in the Iberian Peninsula under contrasting conditions. As photosynthesis and hydraulic capacities often co‐scale, we hypothesize that these species differ in mesophyll conductance to CO₂ (g_m). g_m and key anatomical traits were measured in both species. Drought‐adapted population of A. pinsapo has higher photosynthesis than the more mesic population of A. alba, in agreement with its higher hydraulic capacity. However, A. alba exhibits the largest stomatal conductance (g_s), and so water use efficiency (WUE) is much higher in A. pinsapo. The differences in photosynthesis were explained by differences in g_m, indicating a correlation between hydraulic capacity and g_m. We report a case where g_m is the main factor limiting photosynthesis in one species (A. alba) when compared with the other one (A. pinsapo). The results also highlight the discrepancy between g_m estimates based on anatomical measurements and those based on gas exchange methods, probably due to the very large resistance exerted by cell walls and the stroma in both species. Thus, the cell wall and chloroplast properties in relation to CO₂ diffusion constitute a near‐future research priority.     

自发性高血压大鼠中枢血管紧张素Ⅱ的变化对中枢肾上腺素和去甲肾上腺素含量的影响

自发性高血压大鼠中枢肾上腺能递质含量异常,然其原因仍不清楚。本工作发现:12周龄易卒中型自发性高血压大鼠(SHRSP)脑桥,下丘脑后部、尾核中去甲肾上腺素(NE)含量及延髓、下丘脑前部,下丘脑后部中肾上腺素(E)含量均高于同龄 Wista Kyoto 大鼠(WKY),SHRSP 中枢 AⅡ含量亦明显高于同龄 WKY;向8周龄 SHRSP 和 WKY 侧脑室慢性灌注巯甲丙脯氨酸,不仅降低动脉血压及各脑区AⅡ含量,亦使中枢 NE 及 E 水平下降,但巯甲丙脯氨酸对 SHRSP 的影响远较对 WKY 明显。结果提示:SHRSP 中枢肾上腺能递质含量增加可能与 SHRSP 中枢 AⅡ量含量升高以及 SHRSP 中枢 AⅡ对中枢肾上腺能递质的促释放调节机制明显易化有关。     

家兔外膝体背核中继细胞的被动电缆特性

在离体脑片上测定了２４个家兔外膝体中继细胞的被动膜特性。它们的静息电位为－６２．７±４．１ｍＶ（ＳＤ）;膜输入阻抗为３０．４±１１．２ＭΩ。运用Ｒａｌｌ的线性电缆模型,计算出这些神经元树突的电紧张长度（Ｌ）为０．７９±０．１３;电压衰减因数（Ｈ）为回．３３±０．１１。说明家兔外膝体中继细胞是电学紧密的,树突远端的电位可扩散到胞体,幅度仅衰减２５％左右。     

Hydraulic Parameters Measured in 1-Year-Old Twigs of some Mediterranean Species with Diffuse-Porous Wood: Changes in Hydraulic Conductivity and Their Possible Functional Significance

We report measurements of hydraulic conductivity of Vitis oinifera,Oleo europaea and Populus deltoides 1-year-old twigs. Singleserial internodes were tested for the volume flow rate whichwas related to: (a) the xylem tissue cross-sectional area, (b)the vessel lumina cross-sectional area and (c) the leaf surfacearea supplied by a given stem section. From this, whole xylemhydraulic conductivity (L_x), vessel lumina hydraulic conductivity(L_xv) and leaf specific conductivity (LSC) were calculated.All the three parameters turned out to be linearly related toeach other. This is kcause: (a) the leaf surface area (A₁) waslinearly related to xylem cross-sectional area (A_x and (b) theratio of the vessel lumina cross-sectional area (A_xv) to xylemcross-sectional area (A_x) was approximately constant along thetwigs. Moreover, the hydraulic conductivity of twig segmentswhere buds grow most actively (distal internodes in V. viniferaand proximal ones in O. europaea) was much lower than in therest of the twigs. A possible role played by these ‘constricted’twig regions is discussed. Key words: Changes, Hydraulic conductivity, Stem     

Isolation and characterization of microsatellites in a marine food fish species,golden trevally Gnathanodon specious

The first set of six polymorphic microsatellites was isolated from a partial genomic DNA library of an important marine food fish Gnathanodon specious, and was characterized in 28 unrelated individuals. The allele number ranged from three to 12 with an average of seven/locus; average expected heterozygosity was 0.57 ranging from 0.10 to 0.87, whereas the observed heterozygosity ranged from 0.11 to 0.96 (average: 0.57). All six markers conform to Hardy–Weinberg and linkage equilibria. These markers will be useful for accessing genetic population structure of wild populations and for selective breeding program in fish farms.     

Colonization of the Aeolian Islands by Pimelia rugulosa rugulosa Germar, 1824 (Coleoptera: Tenebrionidae) inferred from the genetic structure of populations: geological and environmental relations

The darkling beetle Pimelia rugulosa rugulosa Germar, 1824 was selected to investigate the process of colonization in a volcanic archipelago and the role of volcanism in determining spatial patterns of genetic variability. Analyses were conducted in the Aeolian Islands, located in the central Mediterranean directly off the Sicilian coast. Genetic variability and geographic structure were studied in individuals from each island of the archipelago based on sequences of the cytochrome c oxidase subunit 2 mitochondrial gene; a network approach was employed to identify haplotype lineages. A strong genetic structure, with no haplotype sharing among islands, was observed. Six separate lineages were identified that independently colonized different islands of the archipelago from the mainland and differentiated locally to form small haplogroups. Variability of observed haplogroups is correlated with island age and a positive correlation between tenebrionid diversity and mitotype diversity is reported. Some, yet undescribed, catastrophic event is hypothesized to explain the depletion of a substantial part of the genetic, as well as biological diversity in the island of Filicudi. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 104 , 29–37.     

A molecular phylogeny of the genus Apis suggests that the Giant Honey Bee of the Philippines,A. breviligula Maa,and the Plains Honey Bee of southern India,A. indica Fabricius,are valid species

Two new taxa have been added to the existing molecular phylogenies of the genus Apis. The new phylogeny supports the accepted phylogenetic relationships of {dwarf honey bees [giant honey bees (cavity‐nesting honey bees)]}. Based on Bayesian and maximum parsimony trees, our analysis supports recognition of Apis indica, the Plains Honey Bee of south India, as a separate species from A. cerana. Our analysis also supports recognition of the Giant Philippines Honey Bee, A. breviligula, as a separate species from A. dorsata.     

尖叶木樨榄作砧木嫁接油橄榄的研究

本文就云南、四川两省采用尖叶木樨榄(Olea ferrugineaRoyle.)作砧木嫁接油橄榄(Olea europaea L.)二十余年的试验观察,报道尖叶木樨榄在我国的分布及其生物学特性,系统总结尖叶木樨榄作砧木对油橄榄生长发育及开花结实的影响。试验结果表明:尖叶木樨榄作砧木具有种子出苗率高,嫁接繁殖容易,提早油橄榄开花结实年龄,增强油橄榄对酸性红壤的适应性,增强油橄榄对干旱环境和对某些病害的抗性等优点。此砧木已在我国西南部油橄榄适生区应用于生产性栽培。