Complete genome sequencing of sixteen Francisella noatunensis subsp. orientalis isolates: A genomic approach for molecular characterization and spread dynamics of this clonal population

Francisella noatunensis subsp. orientalis (FNO) is an important emerging pathogen associated with disease outbreaks in farm-raised Nile tilapia. FNO genetic diversity using PCR-based typing, no intra-species discrimination was achieved among isolates/strains from different countries, thus demonstrating a clonal behaviour pattern. In this study, we aimed to evaluate the population structure of FNO isolates by comparing whole-genome sequencing data. The analysis of recombination showed that Brazilian isolates group formed a clonal population; whereas other lineages are also supported by this analysis for isolates from foreign countries. The whole-genome multilocus sequence typing (wgMLST) analysis showed varying numbers of dissimilar alleles, suggesting that the Brazilian clonal population are in expansion. Each Brazilian isolate could be identified as a single node by high-resolution gene-by-gene approach, presenting slight genetic differences associated to mutational events. The common ancestry node suggests a single entry into the country before 2012, and the rapid dissemination of this infectious agent may be linked to market sales of infected fingerlings.     

The transiently pubescent young leaves of plane (Platanus orientalis) are deficient in photodissipative capacity

We have analyzed reflectance changes and carotenoid composition of young and mature leaves of Platanus orientalis L. in order to test the hypothesis that the transient occurrence of highly absorptive and reflective leaf hairs of young leaves (M. Ntefidou and Y. Manetas 1996, Aust. J. Plant Physiol. 23: 535–538) may be correlated to a weakly developed photodissipative capacity in the chloroplast. Compared to mature leaves, young leaves showed negligible reflectance changes at 530 nm upon sudden illumination, possibly indicating a limited production of zeaxanthin. In addition, actual pigment analysis confirmed lower pools of xanthophyll cycle components and reduced capacity for violaxanthin photoconversion in young leaves. Accordingly, the epoxidation state at saturating photon fluence rates was particularly high. A notable feature of xanthophyll cycle interconversions in young leaves was the inability to drive the system to complete de-epoxidation, as antheraxanthin in the light was always higher than zeaxanthin. Among the rest of the carotenoids, the levels of β-carotene were particularly low. Moreover, most of the photosynthetic pigments were considerably bleached when young leaves were exposed to high light. The above results strongly suggest that young leaves possess a limited photodissipative capacity and therefore, the presence of leaf hairs affords protection against excess light. When the leaf has matured and presumably the concentrations of photoprotective compounds are adequate, the loss of hairs is not of consequence. In fact, their presence on mature leaves may reduce the photosynthetically active radiation to non-saturating levels for photosynthesis.     

CELL CYCLE DEPENDENT VIRUS PRODUCTION IN MARINE PHYTOPLANKTON1

In this study we investigated virus production in two marine phytoplankton species and how it relates to the host's cell cycle. Phaeocystis pouchetii (Hariot) Lagerheim and Pyramimonas orientalis McFadden, Hill & Wetherby, growing synchronously in batch cultures, were infected with their respective viruses (PpV and PoV) at four different stages in the cell cycle and the production of free virus was then measured for 30 h. The virus production in P. orientalis infected with PoV depended on the time of infection, whereas no such relation was found for P. pouchetii infected with PpV. The P. orientalis cultures infected at the end of the dark period and at the beginning of the light period produced three times more virus than those infected in the middle of the light period and eight times more virus than those infected at the beginning of the dark period. The latent periods for PpV and PoV were 12–14 h and 18–20 h, respectively, and in both cases were independent of the host cell cycle. The differences in virus production may be attributed to light or cell cycle dependent regulation of host infection, metabolism, or burst size. Regardless of the mechanism, these differences may be related to differences in the ecological strategies of the hosts and their ability to form blooms.     

Effects of delayed mating on reproductive output of female oriental beetle Anomala orientalis (Coleoptera: Scarabaeidae)

1 Although management of the oriental beetle Anomala orientalis (Waterhouse) by mating disruption shows promise across a range of agricultural systems, relatively little is known about aspects of the reproductive biology of this species relevant to its management. We studied the effects of delayed mating on several aspects of the oviposition behaviour and biology of the oriental beetle using females mated in the laboratory at 4–13 days posteclosion. 2 Females exhibited a gradual decline in fecundity with increased age at mating that was largely a function of a decline in duration of the oviposition period, as well as lower female fertility: females mated at 11 days were less likely to lay any fertile eggs. However, egg fertility did not vary with female age at mating. 3 Because mating delay did not affect longevity, females mated at older ages experienced decreased oviposition periods; however, females laid more eggs per day with increased age at mating, which partially offset shorter oviposition periods. 4 A mating delay of ≥ 6 days relative to females mated within the first day of reaching sexual maturity resulted in an approximately 35–50% lower mean fecundity. 5 These results suggest that, for mating disruption to be a successful management tool for the oriental beetle, mating must be prevented rather than delayed. We compare the findings of the present study with the published research on delayed mating in moths and discuss the importance of these results in relation to management of the oriental beetle using female sex pheromones.     

Effects of different Rhododendron control methods in eastern beech (Fagus orientalis Lipsky) ecosystems in the western Black Sea region of Turkey

Intensive weed control and plot preparation practices have become a critical and integral part of productive beech forest management in Turkey’s coastal Black Sea region (BSR). This study was conducted in an eastern beech forest of 100+ year old in the BSR to evaluate ecosystem effects of three different experimental Rhododendron ponticum understory control methods with a randomised block design, including manual grubbing, foliar and cut stump spraying with imazapyr (Arsenal) and foliar and cut stump spraying with triclopyr (Garlon). Untreated vegetation plots served as controls. Evaluation of these treatments included their effects on understory and forest floor biomass and nutrients (C, N, P, S, K, Ca and Mg) and effects on soils, including bulk density, pH, soil nutrients (C, N, P and S), exchangeable cations (K, Ca and Mg) and soil cation exchange capacity (CEC). Grubbing and imazapyr treatments had greatly reduced the amount of understory biomass 5 years after application (P = 0.002). Triclopyr treatment also had a major effect on understory vegetation control, but by 5 years later, about 10% of the rhododendron originally present on these plots had gradually re‐sprouted and partially covered the plots. Five years after woody vegetation control treatments, at the 0‐ to 20‐cm depth, treatments did not appear to affect soil bulk density, pH and CEC. For the upper 20‐cm soil depth, the exchangeable soil K concentration at the 10‐ to 20‐cm depth on triclopyr‐treated plots was 33% higher than on grubbing plots, and it was twice that of imazapyr application plots. Imazapyr plots had almost 11 times more dead organic matter on the forest floor than there was on grubbing plots. Forest floor C concentrations on imazapyr plots were 26 and 14% greater than those on grubbing and triclopyr plots, respectively. Total ecosystem (forest floor + understory + soil exchangeable) Ca content was 50% higher on imazapyr plots than that on triclopyr plots, while the ecosystem K pool on imazapyr treatment plots was 27% lower than that on triclopyr plots. Herbicides can be used as an alternative for achieving some forest management objectives when other vegetation control methods are not feasible or economical. It is recommended that vegetation control not be used on steep slopes because of greater risk of soil erosion. There may be benefits in encouraging slash disposal by fire after imazapyr treatments, thus removing recalcitrant understory residues left on the forest floor and releasing the essential nutrients within them.     

Studies on the Population and Community Characteristics in Platycladus orientalis Forest

The population and community characteristics in the Platycladus orientalis forest on Qianfo Mountain in Jinan are studied. The specific composition, spatial pattern, biological spectrum and main species dispersions are reported. It is found that all the main species dispersions are aggregated. The diversity of Shannon-Wiener and Simpson indexes are markedly not correlated with the habitat factors. The patch indexes and niche breadths of the main species have been analysed on such axes as light, soil water and soil organic matter. The value of niche overlap between every two species is high on soil resource axis.     

诱导风信子再生花芽不断分化花被片的研究

通过外源激素及外植体年龄的控制,诱导风信子再生花芽不断分化花被片已经获得成功。在２５０ｄ的继代培养中平均每个花芽可分化７０多片花被片,最多的可分化１４０多片。对这种花芽不断分化花被片的形态发生过程以及生长发育特点的观察表明,花芽的第１轮器官与风信子野生型花基本相同,查花被,它由花被筒及其上部的裂片－花被片组成。     

倭蛙属(无尾目:蛙科)肩带研究

对倭蛙属（Nanorana）已知3种：高山倭蛙（Nanorana parkeri）、倭蛙（N. pleskei）和腹斑倭蛙（N. ventripunctata）的肩带作了连续切片后进行Masson染色,发现其上喙骨（epicoracoid）的融合与重叠的状况与虎纹蛙（Rana rugulosa）较相似,而与无尾目中其它物种已知的肩带形态存在较大的差异.倭蛙属和虎纹蛙等与已知肩带类型的蛙亚科其它的物种在系统进化中可能来源于不同的最近共同祖先.     

阴山山脉天然侧柏林的基本特征

阴山山脉是中国天然侧柏(Platycladus orientalis)林分布的西北界, 侧柏林也是阴山山脉最主要的森林群落之一。它具有较好的固坡、保土、涵养水源及改善生境的作用。为了解阴山山脉天然侧柏林种群、群落特征和空间分布规律以更好地为侧柏林的经营提供理论依据, 我们以阴山山脉大青山及乌拉山段天然侧柏林为研究对象, 通过样方调查, 分析了侧柏林的植物区系特征, 并根据群落各层片物种优势度将该区侧柏林划分为6个群丛类型, 分析了各群丛特征及其空间分布的生态序列。结果表明: (1)阴山山脉天然侧柏林群落共出现维管植物96种, 隶属于30科70属, 种的地理成分包括8个类型18个亚型, 其中东古北极分布最多, 其次为东亚分布; (2)从群落结构分析, 发育良好的侧柏群落表现为完整的乔木层和草本层, 灌木盖度普遍偏低, 基本不能成层, 在干扰较为严重的地段甚至消失; (3)各群丛侧柏的径级结构基本呈正态分布, 属于稳定的群落类型, 侧柏的平均株高随胸径的增大整体呈增长型; (4)该区侧柏林受干扰较严重, 加之严酷的生境条件, 建群种侧柏的平均胸径较小且植株分叉较多, 不适合作为用材林, 建议将其作为生态公益林及种源林加以保护利用。     

Systematic revision of the genus Reinboldiella (Ceramiaceae,Rhodophyta) from Taiwan based on comparative morphology and rbcL sequence analyses,including two new species of Reinboldiella

The genus Reinboldiella essentially consists of tiny, membranous blades, epiphytic on benthic red algae, with a wide distribution in the north-western Pacific Ocean (Taiwan, Korea and Japan). In this study, we re-examined the generitype R. schmitziana from Taiwan and neighbouring islands. Two new species of Reinboldiella, R. orientalis sp. nov. and R. taiwanensis sp. nov. are recognized from Taiwan based on comparative morphological studies and molecular analyses of RuBisCO large subunit (rbcL) gene sequences. Reinboldiella orientalis is characterized by its rosette-like appearance, with both erect and prostrate, membranous flat blades whereas R. taiwanensis is distinguishable by mainly consisting of erect, membranous blades with few, short prostrate blades in basal parts of the thalli. Thalli of R. schmitziana also have a rosette-like appearance, but their erect flat blades have cylindrical bases or stipes. The rbcL phylogenetic analyses also support the separation of R.‘schmitziana’ from Taiwan and R. schmitziana from Japan and Korea.