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1.
The racemic total synthesis of elegansidiol, farnesiferol B, and farnesiferol D has been obtained following a Diels–Alder approach. Gillman addition, cross metathesis reaction are the other key steps involved in the target synthesis.  相似文献   

2.
Summary

The life cycle of the Batrachospermales (freshwater florideophyte red such as Batrachospermum, Lemanea) is a shortened variant of the ‘normal’ marine florideophyte life cycle. The perennial Chantransia diploid phase is microscopic and encrusting. Each winter it produces one or more semi-erect haploid gametophytes by vegetative meiosis. Gamete production and fertilization is followed by production of diploid carposporophytes; these produce diploid carpospores which disperse, and regenerate the Chantransia phase. The question of the extent to which the Chantransia phase contributes resources to the gametophyte was approached by physiological-hydrodynamic modelling. These computations suggest that the photosynthetic rates in situ on an area basis are 20 times greater for the gametophyte than the Chantransia phase; this agrees with the observed ratios of peak biomass. The conclusion is that the Chantransia phase has a negligible role in provisioning the growing gametophyte, and that the role of the Chantransia phase is to occupy space with living biomass throughout the year, including exposure at summer drawdown, and (perhaps) by dispersal via production of monospores. A similar conclusion is arrived at on the basis of biomass data for the role of the perennial ‘mushroom’ phase of the semelparous marine Fucalean brown alga Himanthalia elongata in relation to the short-lived but much larger reproductive receptacles.  相似文献   

3.
Lineus viridis is a common nemertean species of North-Atlantic intertidal sand flats. Its mating behaviour is peculiar insofar as this species is reported to be polyandric. However, detailed information on this topic is lacking. In order to get more data on the reproduction, oogenesis and life history of this species, a population in the Wadden Sea on the Isle of Sylt (North Sea) was studied between 2005 and 2011. We conducted regular surveys, during which we sampled, measured and recorded the sex status of 25–100 individuals at each sampling event; at least three individuals were fixed for histological studies at each sampling date. In addition, animals were kept in the laboratory for 3?years to complement field data on sexual identity. Lineus viridis was found to reproduce annually in several successive year; the females are significantly larger than the males. Oogenesis starts in spring, shortly after the preceding reproductive period, and continues until the end of December. Spermiogenesis starts in late autumn and also ends late in December. During mating, several males are generally found crawling on a single female, which forms a cocoon that encloses both the female and the associated males. Fertilization is internal. While females discharge all of their eggs during a single mating event and lose more than 40% of their wet weight, males only empty a few of their gonads, and are thus able to fertilize more than one female. Our study clearly shows that Lineus viridis is a perennial, iteroparous species with a pronounced sexual size dimorphism. During this long-term study, no evidence for sequential hermaphroditism has been found. The observed polyandric mating system in this species raises further questions regarding mate and sperm competition that deserve additional research.  相似文献   

4.
Pharyngodon medinae García-Calvente, 1948 (Nematoda: Pharyngodonidae) is redescribed from Podarcis pityusensis (Bosca, 1883) (Sauria: Lacertidae) of the Balearic Islands (Spain) and confirmed as a member of the genus Skrjabinodon Inglis, 1968. A systematic review of S. medinae and closely related species is also given. Parathelandros canariensis is referred to Skrjabinodon as a new combination and Parathelandros Magzoub et al., 1980 is dismissed as a junior homonym of Parathelandros Baylis, 1930.  相似文献   

5.
The Sordariomycetes is an important group of fungi whose taxonomic relationships and classification is obscure. There is presently no multi-gene molecular phylogeny that addresses evolutionary relationships among different classes and orders. In this study, phylogenetic analyses with a broad taxon sampling of the Sordariomycetes were conducted to evaluate the utility of four gene regions (LSU rDNA, SSU rDNA, beta-tubulin and RPB2) for inferring evolutionary relationships at different taxonomic ranks. Single and multi-gene genealogies inferred from Bayesian and Maximum Parsimony analyses were compared in individual and combined datasets. At the subclass level, SSU rDNA phylogenies demonstrate their utility as a marker to infer phylogenetic relationships at higher levels. All analyses with SSU rDNA alone, combined LSU rDNA and SSU rDNA, and the combined 28 S rDNA, SSU rDNA and RPB2 datasets resulted in three subclasses: Hypocreomycetidae, Sordariomycetidae and Xylariomycetidae, which correspond well to established morphological classification schemes. At the ordinal level, the best resolved phylogeny was obtained from the combined LSU rDNA and SSU rDNA datasets. Individually, the RPB2 gene dataset resulted in significantly higher number of parsimony informative characters. Our results supported the recent separation of Boliniaceae, Chaetosphaeriaceae and Coniochaetaceae from Sordariales and placement of Coronophorales in Hypocreomycetidae. Microascales was found to be paraphyletic and Ceratocystis is phylogenetically associated to Faurelina, while Microascus and Petriella formed another clade and basal to other members of Halosphaeriales. In addition, the order Lulworthiales does not appear to fit in any of the three subclasses. Congruence between morphological and molecular classification schemes is discussed.  相似文献   

6.
Esenbeckia (Esenbeckia) rafaeli, sp.nov. is described and figured from nine specimens collected in Carolina, state of Maranh?o, Brazil. The new species is compared with the species Esenbeckia (Esenbeckia) laticlava Wilkerson & Fairchild, 1983; Esenbeckia (Esenbeckia) bitriangulata Lutz & Castro, 1935 e Esenbeckia (Esenbeckia) enderleini Kr?ber, 1931.  相似文献   

7.
《Comptes Rendus Palevol》2014,13(5):421-441
The paralic flora and fauna from the Late Jurassic of Chassiron (Oléron Island, western France) are described. The Tithonian-aged bonebeds of Purbeck facies of this locality have yielded a rich and diverse vertebrate assemblage including fishes, amphibians, reptiles and mammals, alongside numerous plant and invertebrate remains. The Chassiron locality thus appears as a peculiar Konzentrat-Lagerstätte in which most of the palaeoecosystem's biological components (both aquatic and terrestrial) have been preserved. The depositional environment was probably subject to salinity fluctuations, as indicated by the co-occurrence of freshwater and euryhaline organisms. This is one of the richest localities and the first mammal-bearing site known from the Jurassic of France.  相似文献   

8.
9.
This computational study is intended to shed light on the crystalline and molecular structure, together with the hydrogen bonding (H-bonding) differences between two forms of native cellulose. DFT calculations were carried out to characterize the 17O, 1H and 13C nuclear magnetic resonance (NMR) parameters in cellulose Iα and Iβ with the B3LYP functional employing the 6–311++G7 and 6–31+G1 basis sets. Geometry optimization revealed that the average HB length is shortened by 0.01–0.08 Å when the chains are aligned, whereas the average bond angle increases by about 4–8° exhibiting the enhancement of HB strength. For the isolated cellotetramer chains, the isotropic 17O–H chemical shifts were plotted as a function of HB length. Our results indicated that as the HB length in cellotetramer Iα increases, the 17O–H chemical shift isotropy increases, but this parameter changes in the opposite direction for the other structure. Moreover, B3LYP/6–311++G7 calculations reveal that there is an acceptable correlation between the calculated 13C chemical shifts of the two structures and their experimental values.  相似文献   

10.
The Red Palm Weevil, Rhynchophorus ferrugineus (Oliver) (Coleoptera: Curculionidae), is a serious pest of a wide range of plant species including coconut, sago, date and oil palms. The α-amylases are the hydrolytic enzymes that are involved in carbohydrate metabolism in insects. So far nothing is done to demonstrate α-amylase activity of R. ferrugineus. Thus, the aim of the current study was to identify and characterise the α-amylase activity to gain a better understanding of digestive physiology of the insect. Thus, the α-amylase in the gut of red palm weevil was isolated and characterised using starch as a substrate. The study showed that the α-amylase is present in the gut of the insect for carbohydrate digestion. The α-amylase has an optimum pH and temperature of 5 and 40°C. The activity of α-amylase was increased by NaCl and KCl and inhibited by other compounds such as MgCl2, CaCl2, urea, ethylenediaminetetraacetic acid and sodium dodecylsulfate. Native-PAGE electrophoresis of α-amylase showed two isoenzymes, one major and one minor band showing α-amylase importance in the carbohydrate metabolism of the insect. Understanding of the digestive physiology and α-amylase activity of Red Palm Weevil is important when new management strategies for this economically important pest are devised.  相似文献   

11.
The presence of Triatoma nigromaculata was recorded for the first time in Colombia in the rural village La Playa in the province of Cauca. A single female was captured from an outdoor area near a household. The presence of Trypanosoma parasites in the specimen was not established due to the poor condition of the specimen. The epidemiological importance of this finding is discussed with respect to the potential for transmission of Chagas disease in the province of Cauca and, more broadly, in Colombia.  相似文献   

12.
The structure of the ovipositor sclerites and muscles was investigated in Spaziphora hydromyzina (Diptera, Scathophagidae).  相似文献   

13.
Nesticuscitrinus, a species originally placed in Theridion is redescribed based on the syntype series composed by 7 females and a lectotype is designated. All syntypes have broken emboli in their epigynes. Taxonomic position of “Nesticuscitrinus is briefly discussed and its belonging to Nesticidae is doubted.  相似文献   

14.
The adult of Macrelmis pubescens (Grouvelle, 1889) is redescribed, illustrated, a lectotype designated, and new locality information provided. The lectotype is housed in the Grouvelle’s collection in the Muséum national d’Histoire naturelle, Paris, France. The larva of M. pubescens is described, illustrated and compared with the known larvae of the genus. A diagnosis for Macrelmis Motschulsky, 1860 larvae is provided.  相似文献   

15.
A new species of Kritskyia inhabits the urinary bladder of the "curimba", Prochilodus lineatus in the floodplain of the high Paraná river. The new species resembles others members of Kritskyia in the following features: haptor lacking anchors and with 14 hooks marginal, posterior male copulatory organ non articulated with the accessory piece and vagina a sclerotized tube. However, it differs from the known species mainly by the shape of the copulatory complex. This is the third endoparasitic monogenean species reported from freshwater Neotropical fish.  相似文献   

16.
Galactosomum lacteum (J?gerski?ld, 1896) Looss, 1899 metacercariae, encysted on the optic nerve, on the brain and/or on the muscle and the connective of the pharynx and oesophagus, were found in Spicara maena L., S. flexuosa Rafinesque, 1810, S. smaris L. (Centracanthidae), Gobius cruentatus Gmelin, 1789 (Gobiidae), Symphodus tinca L., S. mediterraneus L. (Labridae), Serranus cabrilla L. (Serranidae), Diplodus sargus L. and D. annularis L. (Sparidae) caught in the Gulf of Cagliari (southern Sardinia, Italy). Excysted specimens were identified by some distinctive morphological features: more or less expanded forebody, depending on whether the specimens were living or fixed; tubular excretory bladder extending to the posterior border of the ovary; two-chambered seminal vesicle; asymmetrical and parenchymatous ventral sucker with lines of spines within its cavity; and unarmed gonotyle. Comparison has been made with the congeneric species metacercaria, G. timondavidi Pearson & Prévot, 1971, also registered in the Mediterranean Sea.  相似文献   

17.
The seasonal distribution of Acanthocephalus tumescens (Acanthocephala : Echinorhynchidae) among Galaxias maculatus (Pisces : Galaxiidae) in Lake Gutiérrez was studied from March 1994 to June 1996. Acanthocephalus tumescens always occurs in the intestine, has an overdispersed frequency distribution, a similar proportion of sexes, and females are larger than males. Mean intensity and prevalence are low and increase with host length. The pattern of the infection shows seasonality, with recruitment in winter and a reproductive period during spring-summer.  相似文献   

18.
The present work aims at comparing the life cycle and estimating, based on life tables, the patterns of fertility of populations of A. aegypti (L.). The life cycles were studied at the temperature of 26 +/- 2 degrees C, and 12h photophase. The development period, egg viability and larval and pupal survival were evaluated daily as well as adult longevity and fecundity. Tables of fertility life were built. The durations of egg, larva and pupa stages varied from 3,9 to 4,5 days, from 6,4 to 8,3 days and from 2,0 to 2,5 days, respectively. The life table parameters for A. aegypti from Brejo dos Santos, Boqueir?o, Itaporanga and Remígio, being, respectively, Ro = 104,03, 84,58, 113,37 and 91,18; rm = 0,92, 0,78, 0,89 and 0,88; and lambda = 2,50, 2,18, 2,43 and 2,41. The populations of Brejo dos Santos and Itaporanga had the biggest potential of growth in relation to the other populations. The results showed a differentiated pattern of growth and a biotical potential in the populations of A. aegypti originated from different municipal districts of the state of Paraíba.  相似文献   

19.
Insects have several types of sensilla, the characterization of which has been fundamental to understanding the mechanisms of sensory perception in different species. This study aimed to describe the ultrastructure of the sensilla present on the antennae of Alabama argillacea (Hübner, 1823) (Lepidoptera: Erebidae), an important pest of cotton (Gossypium hirsutum L.) crops, as well as their possible variation between sexes. To do this, the antennae of males and females of A. argillacea were analyzed using scanning electron microscopy. Sensilla morphometry was assessed using photomicrographs, from which the lengths and basal and apical diameters of sensilla were measured using the ImageJ program. Seven types of sensilla were identified on the antennae of A. argillacea: sensilla trichodea, sensilla chaetica, sensilla auricillica, sensilla coeloconica, sensilla styloconica, sensilla basiconica, and sensilla Böhm bristles. Differences between the sensilla of males and females were found in their lengths and basal diameters in the distal and proximal regions. This suggests that sensilla functionality may not only vary from one species to another, but also between sexes within the same species. Thus, further transmission electron microscopy and single sensillum recording studies may provide more detailed information on the sensilla of A. argillacea and their functions.  相似文献   

20.
Three species that Navás described - Leucochrysa (Nodita) azevedoi Navás, 1913, Leucochrysa (Nodita) camposi (Navás, 1933) and Leucochrysa (Nodita) morenoi (Navás, 1934) - have received recent taxonomic attention. All three have many similar external features; indeed Navás himself, as well as subsequent authors, have confused the species with each other. Here, (a) misidentifications are corrected; (b) a neotype of Leucochrysa azevedoi is designated; (c) Leucochrysa (Nodita) morenoi, previously synonymized with Leucochrysa (Nodita) camposi, is recognized as a valid species [Reinstated status] All three species are redescribed and illustrated, with special emphasis on the types. Leucochrysa (Nodita) azevedoi was found to be relatively common in agricultural areas along Brazil's Atlantic coast. The two other species are known only from their type localities: Leucochrysa (Nodita) camposi - coastal Ecuador, and Leucochrysa (Nodita) morenoi - Quito, Ecuador.  相似文献   

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