Sub-lethal effects of off-road vehicles (ORVs) on surf clams on sandy beaches

Ecological impacts of vehicle traffic are a significant environmental management issue on many sandy shores. Impacts usually focus on lethal effects of vehicles to organisms, but sub-lethal effects which could reduce the fitness of macrofauna populations are equally possible but unknown. Consequently, we measured changes in body condition and burrowing performance of the beach clam Donax deltoides subjected to vehicle traffic on sandy shores in eastern Australia. Body mass index of clams on beaches open to traffic was 16% lower, but gonadosomatic index and relative valve thickness were not consistently linked to vehicle access to beaches. By contrast, off-road vehicles significantly impaired the burrowing performance of clams. After experimental exposure to ORV traffic (30 passes) and dislodgement from the sediment, the time taken for clams to re-bury into the sand doubled irrespective of the vehicle weight used. Because burrowing is such a critical function in the behavioural repertoire of sandy beach animals, the traffic-induced changes to organisms' performance found in this study may increase mortality by causing displacement to less favourable habitats by swash, and by intensifying the risk of predation and desiccation. When assessing the ecological impacts of vehicles on beach fauna, it is thus important to consider both lethal and sub-lethal effects.     

Colonization and substratum preference of an introduced burrowing crustacean in a temperate estuary

Habitat use in marine invertebrates is often influenced by multiple abiotic and biotic factors. Substratum composition is one factor known to have a dramatic effect on habitat selection. The Australasian burrowing isopod (Sphaeroma quoianum, H. Milne Edwards 1840) is a common introduced species in many estuaries on the Pacific coast of North America. S. quoianum burrows into a variety of firm substrata including marsh banks (composed of peat, clay, and/or mud), wood, friable rock, and Styrofoam floats. In some areas, isopods achieve high densities and may accelerate the rate of shoreline erosion and damage marine structures; thus, understanding the substratum preference of this species may be important for conservation and management efforts. Field experiments were conducted in Coos Bay, Oregon to examine substratum preference, burrowing rates, and the life stage of colonizers. In three experimental trials (Fall 2005, Spring 2006, Fall 2006), replicates of four intertidal substrata (marsh banks, decayed wood, sandstone, Styrofoam) were deployed near intertidal populations of S. quoianum. The numbers of burrows created in each substratum were enumerated weekly or daily (depending on trial). After the trials were completed, the total numbers of isopods inhabiting each substratum were counted. In weeks, S. quoianum extensively burrowed the substrata but exhibited a distinct preference for decayed wood. Significantly more isopods were present in wood than the other substrata at the end of the experiments and rates of burrowing were greatest in wood, although significance varied across time in one trial. Nearly 90% of colonizing isopods were under 5 mm in length suggesting that juvenile isopods primarily colonize intertidal substrata. Differences between burrow densities measured in the field and the results from these preference trials may indicate other factors, such as relative availability of substrata, recruitment and dispersal limitations, and possible gregarious behavior also influence local isopod densities.     

Activity patterns, feeding and burrowing behaviour of the crab Ucides cordatus (Ucididae) in a high intertidal mangrove forest in North Brazil

Activity patterns, feeding and burrowing behaviour of the economically important semi-terrestrial mangrove crab Ucides cordatus (Ucididae, L. 1763) was studied in a high intertidal Rhizophora mangle forest stand in Bragança, North Brazil. Video observations in the rainy and dry season were conducted over 24 h cycles at different lunar phases to investigate the behaviour of these litter-feeding crabs outside their burrows. During the rainy season, crabs stayed inside their burrows for 79% and 92% of the time during day and night, respectively. Time spent for feeding, burrowing and other activities outside their burrows was significantly longer during the day with 9.9% (night: 1.7%) and at waning and waxing moon with 9% (full and new moon: 0.9%). At neap tides (no tidal inundation) foraging and feeding activities outside burrows were clearly light-dependent, increasing at dawn and decreasing at dusk. Highest activities during daytime relate to the visual localisation of food. During the dry season, crabs spent less time inside burrows at neap tides than during the rainy season (80% and 91%, respectively). However, time spent for feeding activities was similar during both seasons. During almost all observation periods crabs collected leaf litter, but rarely fed on it outside burrows. At neap tides nearly all available litter was collected, suggesting that the U. cordatus population is litter-limited during these times. At spring tides (regular tidal inundation) the surface activity of U. cordatus was tide-dependent. Crabs closed their burrow entrances 2-3 h before flooding and re-emerged as soon as the tide retreated. During the day, burrow maintenance was the second most frequent behaviour after feeding. Agonistic interactions were regularly observed and were mainly related to burrow defence. The mean foraging radius of the crabs was only 19 cm (max: 1 m) underneath high Rhizophora mangle trees where crab densities were high. The results point to a high competition for burrows and show that U. cordatus is territorial. It is concluded that several exogenous factors, in particular light, leaf litter availability, flooding of burrows and the presence of conspecifics are important in controlling the crabs' activity patterns.     

Swimming in the sea hare Aplysia brasiliana: Cost of transport, parapodial morphometry, and swimming behavior

The energetics and behavior of the parapodial-swimming Aplysia brasiliana were investigated in order to compare net cost of transport (COT_net) between swimming and crawling, and to compare transport costs with other swimmers. Oxygen consumption (V_O2) increased with increasing animal mass for resting, crawling, and swimming animals. Slopes of the regressions of log V_O2 on log mass were 0.90, 0.91, and 0.89 for resting, crawling, and swimming, respectively. The regression for resting V_O2 on mass was significantly lower than regressions of crawling and swimming on mass, which fell into a statistically homogenous subgroup. During 4-h swimming bouts, parapodial beat frequency dropped by less than 10% of starting values after 2 h and then stabilized for the remainder of the trial, whereas velocity steadily decreased to about 70% of starting values over the 4-h period. Initial beat frequency (at the start of a swimming bout) was negatively related to body mass, varying from 1.1 beat s^− 1 for a 34 g individual to 0.7 beats s^− 1 for a 500 g individual. Final beat frequency (at the end of a swimming bout) was also negatively related to body mass, but had a significantly lower intercept than initial beat frequency. Neither initial swimming velocity nor final swimming velocity was related to mass, but final velocity was significantly lower than initial velocity. A 250 g A. brasiliana swam at 345 m h^− 1 and crawled at 7 m h^− 1. Swimming COT_net (0.1 ml O₂ kg^− 1 m^− 1) for a 250 g A. brasiliana was 50 times less than crawling COT_net (5.3 ml O₂ kg^− 1 m^− 1). While the crawling COT_net for A. brasiliana fell within the range of other marine gastropods, swimming COT_net was less than that of swimming crustaceans, and much less than another gastropod, Melibe leonina, that uses lateral bending to swim.     

Patterns of intermediate host use and levels of association between two conflicting manipulative parasites.

For many parasites with complex life cycles, manipulation of intermediate host phenotypes is often regarded as an adaptation to increase the probability of successful transmission. This phenomenon creates opportunities for either synergistic or conflicting interests between different parasite species sharing the same intermediate host. When more than one manipulative parasite infect the same intermediate host, but differ in their definitive host, selection should favour the establishment of a negative association between these manipulators. Both Polymorphus minutus and Pomphorhynchus laevis exploit the amphipod Gammarus pulex as intermediate host but differ markedly in their final host, a fish for P. laevis and a bird for P. minutus. The pattern of host use by these two conflicting manipulative parasites was studied. Their incidence and intensity of infection and their distribution among G. pulex were first examined by analysing three large samples of gammarids collected from the river Tille, Eastern France. Both parasites had low prevalence in the host population. However, temporal fluctuation in the level of parasitic infection was observed. Overall, prevalence of both parasite species was higher in male than in female G. pulex. We then assessed the degree of association between the two parasites among their intermediate hosts, using two different methods: a host-centred measure and a parasite-centred measure. Both measures gave similar results; showing random association between the two acanthocephalan species in their intermediate hosts. We discuss our results in relation to the selective forces and ecological constraints that may determine the pattern of association between conflicting manipulative parasites.     

Influence of two different diets on fluid and particle retention time Javan langur (Trachypithecus auratus auratus)

In captivity, langurs (foregut fermenting primates) often suffer from digestive disorders, and in particular display soft stools on diets with a high proportion of fruits, vegetables, and grain products. In this study, we tested whether the improvement in feces consistency expected after an omission of vegetables from a conventional diet was also accompanied by a change in the excretion pattern as measured by the mean retention time (MRT). Two adult Javan langurs were kept together and offered a conventional diet of pellets, browse, vegetables, or a diet consisting of pellets and browse only. MRT were measured with cobalt-EDTA as the fluid and chromium oxide as the particle marker before, during, and after the test diet, collecting the feces of both animals together. MRTs of fluids and particles were longer (47/49 h) on the test diet as compared to the usual diet (42/43 h). Feces consistency improved during the test period. The test period was marked by an increased fiber intake; however, on the conventional diet, dietary water intake exceeded the calculated water flux for these animals distinctively, due to the high proportion of vegetables. Therefore, it cannot be decided whether the increase of fiber level alone or also a reduction of the excessive water intake was responsible for the changes observed. Comparing the results of this study to other studies on ingesta retention in foregut fermenting primates, no correlation between the body mass of the animals and the MRTs measured is evident, which is in accordance with observations in other groups of foregut fermenters.     

Identification and comparison of natural rubber from two Lactuca species

Renewed interest in the identification of alternative sources of natural rubber to Hevea brasiliensis has focused on the Compositae family. In our search for Compositae models for rubber synthesis, we extracted latex from stems of two lettuce species: Lactuca serriola, prickly lettuce, and Lactuca sativa cv. Salinas, crisphead lettuce. Both species contained cis-1,4-polyisoprene rubber in the dichloromethane-soluble portions of their latex, and sesquiterpene lactones in their acetone-soluble portions. The rubber from both species and their progeny had molecular weights in excess of 1,000,000g/mol, and polydispersity values of 1.1. Rubber transferase activity was detected across a range of farnesyl diphosphate initiator concentrations, with decreased activity as initiator concentrations exceeded putative saturation. These results add lettuce to the short list of plant species that produce high molecular weight rubber in their latex. Due to the genomic and agronomic resources available in lettuce species, they provide the opportunity for further dissection of natural rubber biosynthesis in plants.     

Molecular characterization and enzymatic activity of laccases in two Pleurotus spp. with different pathogenic behaviour

Pleurotus eryngii and P. ferulae, two species belonging to the P. eryngii complex, synthesize laccases, ligninolytic enzymes that play a role in the host-pathogen interaction in the first step of infection. Ecological studies have shown that although both fungi have been recognized as saprophytes, P. eryngii weakly pathogenic when colonizing the roots and stems of Eryngium campestre, whereas P. ferulae is mostly pathogenic to Ferula communis. The paper describes the genomic organization of four putative laccase genes (lac1, lac2, lac3, and lac5-like gene; gene names were assigned on the basis of sequence homologies) of P. eryngii and P. ferulae. The mRNA expression and enzymatic activity of the laccases were analysed under culture conditions where a source of lignin (wheat bran) or lyophilized roots of E. campestre or F. communis were present. These experiments indicated that the four lac-like genes were differentially regulated in the two mushrooms. Specifically, the addition of the lyophilized roots of the respective host plant to the culture media induced an advance in the mRNA expression of the four lac-like genes and a seven-fold higher total laccase activity in P. ferulae than in P. eryngii. The results obtained are discussed in relation to the possible role of laccases in the interaction of P. eryngii and P. ferulae with their respective host.     

A new species and record of branchial parasitic isopods (Crustacea: Isopoda: Bopyridae: Pseudioninae) of porcellanid crabs from the Philippines

Branchial bopyrids infesting porcellanid crabs from the Philippines were investigated based on intertidal collections made in 1999-2000. Crabs of the genus Petrolisthes collected from sites in the northern Philippines were examined and two parasite species were found. One new pseudionine species found infesting Petrolisthes sp. [cf. Petrolisthes asiaticus (Leach)] is described as Aporobopyrus galleonus (prevalence 6.1%); this species is distinguished from other members of the genus by a setose palp on the maxilliped of the females, barbula morphology, and male characters including the possession of pleopods. This represents the second described species of Aporobopyrus from the Philippines, and the first from porcellanid crabs. In addition, Pleurocrypta macrocephalaNierstrasz and Brender à Brandis, 1923 (originally described from Indonesia) was found infesting the same unidentified Petrolisthes sp. (prevalence 2.6%); this is the first report of the species from the Philippines.     

The effect of natural populations of the burrowing and grazing soldier crab (Mictyris longicarpus) on sediment irrigation, benthic metabolism and nitrogen fluxes

The aim of this study was to determine the effect of sediment grazing and burrowing activities of natural populations of Mictyris longicarpus on benthic metabolism, nitrogen flux and irrigation rates by comparing sediments taken from minimum disturbance exclusion cages and adjacent sediments subject to M. longicarpus activities. M. longicarpus reduced sediment surface chlorophyll a (approximately 77%), organic carbon (approximately 95%) and total nitrogen concentrations (approximately 99%) in comparison to ungrazed sediments. Consequently, they significantly reduced gross benthic O₂ production (about 71%) and sediment O₂ consumption (approximately 46%). Mean N₂ fluxes showed net effluxes (276-430 μmol m⁻² day⁻¹) in the presences of M. longicarpus and net uptakes (194.09-449.21 μmol m⁻² day⁻¹) where they were excluded. The net uptake of N₂ was most likely due to cyanobacteria fixing of N₂, as dense microbial mats became established over the sediment surface in the absence of M. longicarpus grazing activity. Sediment irrigation/transport rates calculated from CsCl tracer dilution indicated greater irrigation rates in the exclusions (12.12-16.22 l m⁻² h⁻¹) compared to inhabited sediments (6.33-11.73 l m⁻² h⁻¹) and this was again was most likely due to the lack of grazing pressure which allowed large populations of small burrowing polychaetes to inhabit the organic matter rich exclusion sediments. As such, the main influence of M. longicarpus was the interception and consumption of transported organic material, benthic microalgae and other small infaunal organisms resulting in the removal of approximately 0.06 g m⁻² day⁻¹ of nitrogen and 12.12 g m⁻² day⁻¹ of organic carbon. This “cleansing” of the sediments reduced sediment metabolism and the flux of solutes across the sediment water interface and ultimately the heavy predation of M. longicarpus by transient species such as stingrays, results in a net loss of carbon and nitrogen from the system.     

饲料中糖水平对不同食性海水鱼类PEPCK基因表达和酶活性的影响

磷酸烯醇式丙酮酸羧激酶(Phosphoenolpyruvate carboxykinase, PEPCK, E.C.4.1.1.32)是水生生物糖异生代谢的关键限速酶. 实验以杂食性罗非鱼(Oreochromis niloticus)、温和肉食性卵形鲳鲹(Trachinotus ovatus)、凶猛肉食性军曹鱼(Rachycentron canadum)三种不同食性海水养殖鱼类为研究对象, 以糊精为饲料糖源, 分别设置不同饲料糖添加水平(低糖组LD、中糖组MD、高糖组HD)等氮等能饲料, 每种鱼分别随机选取60尾体格均匀的幼鱼进行为期8周的饲养实验, 同时克隆卵形鲳鲹胞质型PEPCK基因cDNA全长序列, 以期探讨不同饲料糖水平对不同食性鱼类PEPCK活性及其mRNA表达的影响. 结果显示: 卵形鲳鲹PEPCK基因cDNA共2652 bp, 含1个编码624个氨基酸的开放阅读框, 三种不同食性海水鱼类PEPCK的生物信息学比较分析显示相似度达90%以上, 在结构和功能上具有较高的保守和同源性. 养殖实验结果显示: 随着饲料糖水平的增加, 三种鱼肝脏中PEPCK酶活性均降低, 其中卵形鲳鲹、军曹鱼HD组PEPCK活性比LD组分别显著降低28.05%和26.03% (P0.05). 而其肝脏中PEPCK mRNA表达水平同样均随饲料碳水化合物水平增加而受到抑制, 其中罗非鱼、卵形鲳鲹、军曹鱼中LD组PEPCK的mRNA分别是HD组的100倍、4.3倍和4.77倍. 结果表明鱼类的糖异生能力可能与其食性有关, 三种鱼PEPCK酶活性与基因表达量随着饲料糖水平的增加而受到显著抑制, 且mRNA表达抑制程度随食性不同而具有较大差异, 以杂食性罗非鱼受抑制程度最高, 凶猛肉食性军曹鱼受抑制程度最低.       

Three new species and two new combinations in the Aizoaceae from the Western and Northern Cape of South Africa

Three new species of Aizoaceae from the Western Cape are described. Octopoma tanquanum Klak and Vlokia montana Klak are dwarf shrubby or mat-forming succulents which belong to the Ruschieae in the Ruschioideae. Mesembryanthemum knolfonteinense Klak of the Mesembryanthemoideae is a geophyte. Octopoma tanquanum inhabits relatively low lying arid areas within the Tanqua Karoo and the Little Karoo and is thought to be closely allied to the two species of Octopoma found in the Little Karoo. Both V. montana and M. knolfonteinense grow at relatively high altitudes within the fynbos biome. In addition, Ruschia littlewoodii L.Bolus is transferred to Phiambolia, and two new combinations are made in Antimima for Ruschia hexamera L.Bolus and Ruschia radicans L.Bolus.     

Biochemical compositions of two dominant bloom- forming species isolated from the Yangtze River Estuary in response to different nutrient conditions

Variations of cellular total lipid, total carbohydrate and total protein content of two dominant bloom-forming species (Skeletonema costatum and Prorocentrum donghaiense) isolated from the Yangtze River Estuary were examined under six different nutrient conditions in batch cultures. Daily samples were collected to estimate the cell growth, nutrient concentration and three biochemical compositions content during 7 days for S. costatum and the same sampling procedure was done every other day during 10 days for P. donghaiense. Results showed that for S. costatum, cellular total lipid content increased under phosphorus (P) limitation, but not for nitrogen (N) limitation; cellular carbohydrate were accumulated under both N and P limitation; cellular total protein content of low nutrient concentration treatments were significantly lower than that of high nutrient concentration treatments. For P. donghaiense, both cellular total lipid content and total carbohydrate content were greatly elevated as a result of N and P exhaustion, but cellular total protein content had no significant changes under nutrient limitation. In addition, the capability of accumulation of three biochemical constituents of P. donghaiense was much stronger than that of S. costatum. Pearson correlation showed that for both species, the biochemical composition of three constituents (lipid, carbohydrate and protein) had no significant relationship with extracellular N concentration, but had positive correlation with extracellular and intracellular P concentration. The capability of two species to accumulate cellular total lipid and carbohydrate under nutrient limitation may help them accommodate the fluctuating nutrient condition of the Yangtze River Estuary. The different responses of two species of cellular biochemical compositions content under different nutrient conditions may provide some evidence to explain the temporal characteristic of blooms caused by two species in the Yangtze River Estuary.     

Lipid composition of the red alga Tichocarpus crinitus exposed to different levels of photon irradiance

We examined variations in the lipid composition of the marine red alga Tichocarpus crinitus exposed to different levels of photon irradiance: 70-80% and 8-10% of the incident photosynthetically active radiation (PAR). The content of storage and structural lipids was significantly affected by the light intensity. Exposure of T. crinitus to low light conditions induced an increase in the abundance of structural components of the cell membranes, especially sulfoquinovosyldiacylglycerol, phosphatidylglycerol (PG) and phosphatidylcholine, while growth of algae at high light intensity resulted in a 1.5-folder increase in the level of storage lipids, i.e. triacylglycerols. There were no significant differences in the fatty acid composition of the total lipid pool in algae grown under different light conditions. However, the content of the most unsaturated acid, 20:5n-3, was slightly higher in T. crinitus under 8-10% PAR compared to those at 70-80% PAR. Each lipid class was found to have a characteristic fatty acid composition. The relative proportions of fatty acids esterifying monogalactosyldiacylglycerol (MGDG) and PG were significantly affected by irradiance conditions. Exposure of algae to low light resulted in increase in the content of 20:5n-3 in MGDG and in decrease in the level of this acid in PG. The concentration of trans-16:1 acid in PG increased in algae grown under high light intensity. Light conditions influenced on total lipid content, which made up 4.2+/-0.5 and 3.4+/-0.3 mg g-1 fresh weight in algae exposed to 8-10% PAR and 70-80% PAR, respectively. We suggest that variations in the lipid composition of T. crinitus exposed to different levels of light intensity may be a response of alga to light conditions and it can be considered as one of the mechanisms of adaptation of T. crinitus to varying incident light intensity.     

Development of a real time PCR Taqman assay based on the TPI gene for simultaneous identification of Clostridium chauvoei and Clostridium septicum

In the present study, a Taqman allelic discrimination assay based on three SNPs of the TPI gene is described. It was used as a differential diagnostic tool to detect blackleg and malignant edema. Sudden deaths of grazing ruminants, such as cattle, sheep and goats, which show clinical signs related to hyperacute infective processes, encouraged the development of a rapid and precise diagnostic molecular method. Specific primers and probes for Clostridium septicum and Clostridium chauvoei were designed on the basis of the TPI gene sequence. The multiplex PCR was tested on the DNA of a total of 57 strains, including 24 Clostridium chauvoei, 20 Clostridium septicum, 1 Bacillus anthracis and 12 other Clostridium spp. The DNA samples from Clostridium chauvoei and Clostridium septicum strains were amplified. Amplification of other DNA samples was not observed, with the exception of Clostridium tertium, which showed a weak positive signal. To avoid misdiagnosis, a confirmatory assay based on a Sybr green real time PCR was proposed. The authors confirmed the efficacy and the specificity of the test used in this study, which proved to be a useful tool for the diagnosis of clostridiosis that are often diagnosed using only traditional tools.     

Identification of microRNAs from different tissues of chicken embryo and adult chicken

We report for the first time the identification of 25 microRNAs from tissues originating from chicken embryo and adult chicken. Most of the cloned microRNAs are expressed in both adult chickens and chicken embryos. Fourteen were identified without any prior prediction. One microRNA, miR-757, is thought to be chicken-specific. Three of the microRNAs appear to be extremely tissue specific.     

Distribution and diversity of cry genes in native strains of Bacillus thuringiensis obtained from different ecosystems from Colombia

Colombia is a tropical country located at the north of South America. It is considered to be one of the most important countries in terms of its biodiversity worldwide. One hundred and eight soil samples obtained from agricultural crops and wild ecosystems were evaluated in terms of the presence of Bacillus thuringiensis (Bt) native strains. One hundred and eight different Bt strains were isolated and characterized by the presence of crystal proteins by SDS-PAGE and a multiplex PCR with general and specific primers for cry1 and cry3, cry7, and cry8 gene detection. Most of the Bt strains (73%) reacted with the cry1 general primers; 27.8% of the Bt strains reacted with cry3, cry7, and cry8 general primers and 17.8% of strains did not react with any of these two sets of primers. Thirty different PCR profiles were found in the strains with cry1 genes when they were analyzed with specific primers (cry1A to cry1F). A high frequency of joint occurrence was observed for cry1Aa/cry1Ab, cry1Aa/cry1Ac, cry1Ab/cry1Ac, and cry1C/cry1D genes with a Pearson coefficient of 0.88, 0.74, 0.76, and 0.87, respectively. Other distinctive characteristics were found in the Colombian collection as the presence of 22.2% of native strains which presented, at the same time, lepidopteran and coleopteran active genes. Interesting relations were found as well between the cry gene distribution and the geographical areas sampled. Finally, some strains with moderate to high biopesticide activity against Spodoptera frugiperda (Lepidoptera) and Premnotrypes vorax (Coleoptera) insects were identified, this being important to explore future microbial strategies for the control of these crop pests in the region.     

Time-course for attainment and reversal of acclimation to constant temperature in two Ceratitis species

Acclimation in the thermal tolerance range of insects occurs when they are exposed to novel temperatures in the laboratory. In contrast to the large number of studies that have tested for the ability of insects to acclimate, relatively few have sought to determine the time-course for attainment and reversal of thermal acclimation. In this study the time required for the Mediterranean fruit fly, Ceratitis capitata Wiedemann, and the Natal fruit fly, Ceratitis rosa Karsch, to acclimate to a range of constant temperatures was tested by determining the chill-coma recovery time and heat knock-down time of flies that had been exposed to novel benign temperatures for different durations. The time required for reversal of acclimation for both Ceratitis species was also determined after flies had been returned to the control temperature. Acclimation to 31 °C for only one day significantly improved the heat knock-down time of C. capitata, but also led to slower recovery from chill-coma. Heat knock-down time indicated that acclimation was achieved after only one day in C. rosa, but it took three days for C. rosa to exhibit a significant acclimation response to a novel temperature of 33 °C when measured using chill-coma recovery time. Reversal of acclimation after return to initial temperature conditions was achieved after only one day in both C. capitata and C. rosa. Adult C. capitata held at 31.5 °C initially exhibited improved heat knock-down times but after 9 days the heat knock-down time of these flies had declined to levels not significantly different from that of control flies held at the baseline temperature of 24 °C. In both Ceratitis species, heat knock-down time declined with age whereas chill-coma recovery time increased with age, indicating an increased susceptibility to high and low temperatures, respectively.     

Hypoglycemic activities of A- and B-type procyanidin oligomer-rich extracts from different Cinnamon barks

Procyanidin oligomers in Cinnamon are thought to be responsible for the biological activity in the treatment of diabetes mellitus (DM). To clarify types of procyanidin oligomers in different Cinnamon species and investigate their different effects, the present study investigated procyanidin oligomers in polyphenolic oligomer-rich extracts of three Cinnamon samples by LC-MS methods, and their hypoglycemic activities were detected in vivo and in vitro. The results showed that two of the three samples from Cinnamomum cassia were rich in B-type procyanidin oligomers, and the other sample was rich in A-type procyanidin oligomers. The Cinnamon extracts were administered at doses of 200 and 300 mg/kg body wt. in high-fat diet-fed and low-dose streptozotocin (STZ)-induced diabetic mice for 14 days. The results showed that blood glucose concentrations were significantly decreased in all Cinnamon extract groups compared with the control group (p < 0.05). Administration of the Cinnamon extracts significantly increased the consumption of extracellular glucose in insulin-resistant HepG2 cells and normal HepG2 cells compared with the control group. These results suggest that both A- and B-type procyanidin oligomers in different Cinnamon species have hypoglycemic activities and may improve insulin sensitivity in type 2 DM.     

Biomass allocation, relative competitive ability and water use efficiency of two dominant species in semiarid Loess Plateau under water stress

A better understanding of the growth and interspecific competition of native dominant species under water stress should aid in prediction of succession in plant communities. In addition, such research would guide the selection of appropriate conservation and agricultural utilization of plants in semiarid environments that have not been very well characterized. Biomass production and allocation, relative competitive ability and water use efficiency of one C₄ herbaceous grass (Bothriochloa ischaemum) and one C₃ leguminous subshrub (Lespedeza davurica), both important species from the semiarid Loess Plateau of China, were investigated in a pot-cultivation experiment. The experiment was conducted using a replacement series design in which B. ischaemum and L. davurica were grown with twelve plants per pot, in seven combinations of the two species (12:0, 10:2, 8:4, 6:6, 4:8, 2:10, and 0:12). Three levels of water treatments included sufficient water supply (HW), moderate water stress (MW) and severe water stress (LW). These treatments were applied after seedling establishment and remained until the end of the experiment. Biomass production and its partitioning, and transpiration water use efficiency (TWUE) were determined at the end of the experiment. Interspecific competitive indices (competitive ratio (CR), aggressiveness (A) and relative yield total (RYT)) were calculated from the dry weight for shoots, roots and total biomass. Water stress decreased biomass production of both species in monoculture and mixture. The growth of L. davurica was restrained in their mixtures for each water treatment. L. davurica had significantly (P < 0.05) greater root:shoot allocation than B. ischaemum for each water treatment and proportion within the replacement series. Aggressiveness (A) values for B. ischaemum with respect to L. davurica were negative only at the proportions of B. ischaemum to L. davurica being 8:4 and 10:2 in LW treatment. B. ischaemum had a significantly (P < 0.05) higher CR value under each water treatment, and water stress considerably reduced its relative CR while increased that of L. davurica. RYT values of the two species indicated some degree of resource complimentarity under both water sufficient and deficit conditions. The results suggest that it is advantageous for growing the two species together to maximize biomass production, and the suggested ratio was 10:2 of B. ischaemum to L. davurica because of significantly higher (P < 0.05) RYT and TWUE under low water availability condition.