Efficacy of Trichoderma longibrachiatum in the control of Heterodera avenae

Trichoderma longibrachiatum can be used for the control of Heterodera avenae in crops, but the effectiveness and possible mechanisms are unknown. Here we determined the efficacy and the mechanism responsible for the nematode control in spring wheat (Triticum aestivum L.). Wheat seedlings inoculated with T. longibrachiatum at the concentrations from 1.5 × 10⁴ to 1.5 × 10⁸ spores ml^?1 significantly increased plant height, root length, and plant biomass; decreased H. avenae infection in both rhizospheric soil and roots; and enhanced chlorophyll content, root activity, and the specific activities of resistance-related enzymes (peroxidase, polyphenol oxidase and phenylalanine ammonia lyase), compared to the control. Those reactions occurred soon after T. longibrachiatum inoculation and the effect reached the maximum 7–9 days after inoculation. Promoting competitive plant growth and inducing enzyme-trigged resistance serve as the main mechanism responsible for T. longibrachiatum against H. avenae. T. longibrachiatum can be considered an effective biocontrol agent against H. avenae in wheat.     

Myrothecium verrucaria strain X-16, a novel parasitic fungus to Meloidogyne hapla

Options for control of northern root-knot nematode (NRKN, Meloidogyne hapla) on vegetables are very limited currently. In this study, we characterized the parasitism of Myrothecium verrucaria strain X-16, a new nematophagous fungus, on NRKN at the stages of eggs, J2, and adult females and evaluated its biocontrol efficacy in the greenhouse. Strain X-16 produced conidia that geminated and invaded in 80 h after in contact with eggs, causing the shrinkage and depression of egg shell and blastocolysis of the embryo. The strain also attacked 2nd-stage juveniles by producing developing surface networks of hyphae on the nematode body wall. Strain X-16 attacked adult females by producing dense networks of hyphae on the nematode body wall in 120 h. Strain X-16 had lethal effects (22–71% mortality) against NRKN J2 at the concentration as low as 3.1 × 10⁷ conidia/ml and with the incubation treatment time as short as 24 h. The lethal effects linearly increased with the increase of conidial concentration, with the estimated LC₅₀ values as low as 1.0 × 10⁸ conidia/ml. Soil treatments with strain X-16 at 1%, 2% or 4% (wt/wt) induced significant reductions in J2 nematode counts in 100 g of dry soil, Pf/Pi ratios and root-know index in cucumber in the greenhouse evaluations. These studies are the first to demonstrate that M. verrucaria is able to parasitize NRKN and strain X-16 can be a potential biocontrol agent for management of NRKN.     

Can Beauveria bassiana Bals. (Vuill) (Ascomycetes: Hypocreales) and Tamarixia triozae (Burks) (Hymenoptera: Eulophidae) be used together for improved biological control of Bactericera cockerelli (Hemiptera: Triozidae)?

Bactericera cockerelli (Sulc.) is an important pest of solanaceous crops and a vector of the pathogen Candidatus Liberibacter psyllaurous. Biocontrol of this pest has been attempted with either entomopathogenic fungi or the parasitoid Tamarixia triozae (Burks), but prior to this study, their potential impact in combination had not been studied. The aim of the present study was to evaluate T. triozae parasitism rates on B. cockerelli nymphs that were previously infected for different periods of time by three isolates of Beauveria bassiana (Bals.) Vuill. Two native isolates (BB40 and BB42) and one commercial isolate (GHA) were used. The virulence of these isolates was first estimated against B. cockerelli and T. triozae. LC₅₀ values for the native isolates BB40 and BB42 against B. cockerelli were 9.5 × 10⁵ and 2.42 × 10⁶ conidia mL⁻¹ respectively; they were significantly more virulent than isolate GHA with an LC₅₀ of 1.97 × 10⁷ conidia mL⁻¹. However, isolate GHA was significantly more virulent against T. triozae with an LC₅₀ of 1.11 × 10⁷ conidia mL⁻¹ compared with LC₅₀s of 1.49 × 10⁷ and 1.14 × 10⁸ conidia mL⁻¹ for the native isolates BB40 and BB42 respectively. Groups of nymphs were then inoculated with LC₂₀, LC₅₀ or LC₉₀ concentrations of each isolate and presented to T. triozae as hosts either on the day of inoculation or 1, 2, 3, 4, 5, 6 days after inoculation. Subsequent levels of parasitism were recorded. Overall, parasitism rates were similar in inoculated and control nymphs. No parasitism occurred in nymphs 6 days after fungal inoculation. Parasitoids used to parasitize uninoculated B. cockerelli nymphs survived significantly longer (7.8 days) than parasitoids that had been used to parasitize fungus-inoculated nymphs (7.3 days). This suggests an inability of the parasitoid to avoid infection when foraging on inoculated nymphs. In conclusion, although the parasitism rate in control and fungus-treated nymphs was similar, suggesting a combination of both biological control agents is possible, we believe there are also negative implications for the parasitoid because its survival was greatly reduced after attacking infected nymphs.     

Production of the postharvest biocontrol agent Bacillus subtilis CPA-8 using low cost commercial products and by-products

The aim of this research was to identify a low cost medium based on commercial products and by-products that provided maximum Bacillus subtilis CPA-8 growth and maintained biocontrol efficacy. Low cost media combining economical nitrogen and carbon sources such as yeast extract, peptone, soy products, sucrose, maltose and molasses were tested. Tests were carried out in 250-ml flasks containing 50 ml of each tested medium. Maximum cell growth (>3 × 10⁹ CFU ml^?1) was obtained in defatted soy flour 44% combined with sucrose or molasses media. Second, CPA-8 production was scaled up in a 5-l fermenter and CPA-8 population dynamics, pH and oxygen consumption in the optimized medium (defatted soy flour 44% – molasses) was recorded. In these tests, there was a 5-h lag phase before growth, after which exponential growth occurred and maximum production was 3 × 10⁹ CFU ml^?1 after 20 h. Fruit trials with cells and cell free supernatants from CPA-8 grown in optimized medium maintained biocontrol efficacy against Monilinia fructicola on peaches, resulting in disease reductions up to 95%. CPA-8 populations survived in wounds on inoculated peaches, regardless of the culture media used. The results show that B. subtilis CPA-8 can be produced in a low cost medium combining inexpensive nitrogen and carbon sources (40 g l^?1 defatted soy flour 44%, 5 g l^?1 molasses plus mineral trace supplements) in shake flasks and a laboratory fermenter (5 l). The results could be used to provide a reliable basis for scaling up the fermentation process to an industrial level.     

Assessment of spatial distribution and cysts resources of Artemia in late autumn in Dangxiong Co salt lake

Based on the vertically interval sampling in 25 sampling sites in Dangxiong Co salt lake in 2011, a preliminary investigation on population spatial distribution and cysts resources of Artemia in the lake has been conducted. The study achieves four new progresses. First, the average density of Artemia and Artemia cysts in the lake is 4.157 × 10³ ind. m⁻² and 8.069 × 10⁴ ind. m⁻², respectively. Among Artemia, the adults account for 60.31%; Second, different from other salt lakes in horizontal distribution, the Artemia population mainly distributes in the open water, only a little in the shallow water, and there is no distribution in the longshore area in the north part and the estuary region; Third, in vertical distribution, 44.24% of individuals intensively distribute in the upper water layer within 2.0 m, especially 0–0.2 m, where the average density of Artemia and cysts are maximum (129.488 ind. L⁻¹ and 5.728 ind. L⁻¹, respectively). A decrease of distribution density is accompanied by an increase of water depth basically, the percentage of Artemia and cysts decrease to 0.68% and 4.60%, respectively; Fourth, the cysts resources of 14.96 t in the lake are assessed using contour map. 66.35% of them distributed in 0.0–2.0 m water layer and 49.06% concentrate in the 18.21% areas of the central water; Fifth, quantity of cysts suitable for development in the lake is 2.399 ± 0.320 t, with an upper limit of 0.879 t. The study can provide a reference for the sustainable development and exploitation of Artemia in Dangxiong Co salt lake.     

Germination fluctuation of toxic Alexandrium fundyense and A. pacificum cysts and the relationship with bloom occurrences in Kesennuma Bay,Japan

While cyst germination may be an important factor for the initiation of harmful/toxic blooms, assessments of the fluctuation in phytoplankton cyst germination, from bottom sediments to water columns, are rare in situ due to lack of technology that can detect germinated cells in natural bottom sediments. This study introduces a simple mesocosm method, modeled after previous in situ methods, to measure the germination of plankton resting stage cells. Using this method, seasonal changes in germination fluxes of toxic dinoflagellates resting cysts, specifically Alexandrium fundyense (A. tamarense species complex Group I) and A. pacificum (A. tamarense species complex Group IV), were investigated at a fixed station in Kesennuma Bay, northeast Japan, from April 2014 to April 2015. This investigation was conducted in addition to the typical samplings of seawater and bottom sediments to detect the dinoflagellates vegetative cells and resting cysts. Bloom occurrences of A. fundyense were observed June 2014 and February 2015 with maximum cell densities reaching 3.6 × 10⁶ cells m⁻² and 1.4 × 10⁷ cells m⁻², respectively. The maximum germination fluxes of A. fundyense cysts occurred in April 2014 and December 2014 and were 9.3 × 10³ cells m⁻² day⁻¹ and 1.4 × 10⁴ cells m⁻² day⁻¹, respectively. For A. pacificum, the highest cell density was 7.3 × 10⁷ cells m⁻² during the month of August, and the maximum germination fluxes occurred in July and August, reaching 5.8 × 10² cells m⁻² day⁻¹. Thus, this study revealed the seasonal dynamics of A. fundyense and A. pacificum cyst germination and their bloom occurrences in the water column. Blooms occurred one to two months after peak germination, which strongly suggests that both the formation of the initial population by cyst germination and its continuous growth in the water column most likely contributed to toxic bloom occurrences of A. fundyense and A. pacificum in the bay.     

Bench-scale fermentation of Trichoderma viride on wastewater sludge: Rheology,lytic enzymes and biocontrol activity

Conidiation and lytic enzyme production by Trichoderma viride at different solids concentration of pre-treated municipal wastewater sludge was examined in a 15-L fermenter. The maximum conidia concentration (5.94 × 10⁷ CFU mL⁻¹ at 96 h) was obtained at 30 g L⁻¹ suspended solids. The maximum lytic enzyme activities were achieved around 12–30 h of fermentation. Bioassay against a fungal phytopathogen, Fusarium sp. showed maximum activity in the sample drawn around 96 h of fermentation at 30 g L⁻¹ suspended solids concentration. Entomotoxicity against spruce budworm larvae showed maximum value ≈17290 SBU μL⁻¹ at 30 g L⁻¹ suspended solids concentration at the end of fermentation (96 h). Plant bioassay showed dual action of T. viride, i.e., disease prevention and growth promotion. The rheological analyses of fermentation sludges showed the pseudoplastic behaviour. In order to maintain required dissolved oxygen concentration ≥30%, the agitation and aeration requirements significantly increased at 35 g L⁻¹ compared to 30 and 25 g L⁻¹. The oxygen uptake rate and volumetric oxygen mass transfer coefficient, k_La at 35 g L⁻¹ did not increase in comparison to 30 g L⁻¹ due to rheological complexity of the broth during fermentation. Thus, the successful fermentation operation of the biocontrol fungus T. viride is a rational indication of its potential for mass-scale production for agriculture and forest sector as a biocontrol agent.     

Tradescantia fluminensis,an exotic weed affecting native forest regeneration in New Zealand: Ecological surveys,safety tests and releases of four biocontrol agents from Brazil

In the native range of Tradescantia fluminensis in SE Brazil surveys revealed a natural enemy biota attacking the plant that was rich in potential biocontrol agents for New Zealand (NZ), including nine fungi and 10 herbivorous insect species. Similar surveys in NZ, where T. fluminensis is an invasive exotic weed, revealed no specialist insect herbivores or pathogens. The Brazilian insect herbivores included leafmining, stemboring and gall-forming feeding guilds that were absent in NZ. Mean foliar damage levels per site on T. fluminensis were 7.8× higher for folivores in Brazil cf. NZ, and 21.2× higher for pathogens. The presence of rust pustules, or ‘brown lesions’, on leaves in Brazil was negatively associated with damage by folivores, perhaps indicating an antagonistic interaction. In contrast, damage by the white smut fungus, Kordyana sp., was not negatively associated with folivore damage. Mean dry biomass of T. fluminensis was significantly lower in Brazil (164 g m^?2) cf. NZ (455 g m^?2). In NZ, 85% of sites had biomass measures >200 g m^?2 (the previously determined threshold above which native forest regeneration fails). In Brazil, only 27% of sites had biomass measures >200 g m^?2. Among the insect herbivores, three chrysomelid beetles, Neolema ogloblini, Neolema abbreviata and Lema basicostata were prioritised as potential biocontrol agents. Their larvae cause potentially complementary damage to leaves, shoot-tips and mature stems, respectively. Several pathogens, including a rust, were rejected before we selected the Kordyana species. Host range testing of all four agents showed sufficient host-specificity for consideration for release in NZ. Neolema ogloblini and L. basicostata were field-released in NZ in 2011 and 2012, with the field-release of N. abbreviata due late 2012. An application to release Kordyana sp. in NZ has been made.     

Biocontrol of major postharvest pathogens on apple using Rhodotorula glutinis and its effects on postharvest quality parameters

The biocontrol activity of Rhodotorula glutinis on gray mold decay and blue mold decay of apple caused by Botrytis cinerea and Penicillium expansum, respectively, was investigated, as well as its effects on postharvest quality of apple fruits. The results show there was a significant negative correlation between concentrations of the yeast cells and the disease incidence of the pathogens. The higher concentration of the R. glutinis, the better effect of the biocontrol capacity. At concentrations of R. glutinis 1 × 10⁸ CFU ml^?1, the amount of gray mold decay was completely inhibited after 5 days incubation at 20 °C, after challenge with B. cinerea spores suspension of 1 × 10⁵ spores ml^?1; While the blue mold decay was completely inhibited at concentrations of 5 × 10⁸ CFU ml^?1, at challenged with P. expansum spores suspension of 5 × 10⁴ spores ml^?1_. These results demonstrated that the efficacy of R. glutinis in controlling of gray mold decay of apples was better than the efficacy of controlling blue mold. R. glutinis within inoculated wounds on apples increased in numbers at 20 °C from an initial level of 9.5 × 10⁵ CFU per wound to 2.24 × 10⁷ CFU at 20 °C after 1 day. The highest population of the yeast was recovered 4 days after inoculation, the yeast population in wounds increased by 56.9 times. After that, the population of the yeast began to decline very slowly. R. glutinis significantly reduced the incidence of natural infections on intact fruit from 75% in the control fruit to 28.3% after 5 days at 20 °C, and from 58.3 to 6.7% after 30 days at 4 °C followed by 4 days at 20 °C. R. glutinis treatment had no deleterious effect on quality parameters after 5 days at 20 °C or after 30 days at 4 °C followed by 4 days at 20 °C.     

Spore production in solid-state fermentation of rice by Clonostachys rosea,a biopesticide for gray mold of strawberries

Gray mold caused by Botrytis cinerea is an important disease of strawberry. Clonostachys rosea is a mycoparasite of B. cinerea that reduces fruit losses when used as a biocontrol agent. Since spore production by C. rosea has not been optimized, we investigated factors affecting sporulation under aseptic conditions on white rice grains. The greatest spore production in glass flasks, 3.4 × 10⁹ spores/g-dry-matter (gDM), occurred with an initial moisture content of 46% (w/w wet basis), inoculated with 1 × 10⁶ spores/gDM and hand shaken every 15 days. However, a lower inoculum density (9 × 10³ spores/gDM) and no shaking also gave acceptable sporulation. In plastic bags 1.1 × 10⁸ spores/gDM were produced in 15 days, suggesting that larger scale production may be feasible: with this spore content, 24 m² of incubator space would produce sufficient spores for the continued treatment of 1 ha of strawberry plants.     

Trichoderma from Aceh Sumatra reduce Phytophthora lesions on pods and cacao seedlings

The cocoa tree, Theobroma cacao L., suffers large yield losses in Aceh Indonesia due to the disease black pod rot, caused by Phytophthora spp. Despite having the largest area under cacao production in Sumatra, farmers in the Aceh region have low overall production because of losses to insect pests and black pod rot. Trichoderma spp. were isolated from the roots and leaves of cacao trees and screened as potential biological control agents. Isolates used in the study were Trichoderma asperellum isolates T2 and T4, Trichoderma longibrachiatum isolates T15 and T16, and Trichoderma virens isolates T1 and Tv. T1, T2, T4, and Tv completely colonized and destroyed Phytophthora tropicalis and Phytophthora palmivora mycelium in precolonized plate assays. All six isolates reduced P. tropicalis, but none reduced the growth of P. palmivora in dual plate assays. Phytophthora growth was suppressed on MIN media amended with sterile heat inactivated Trichoderma culture filtrates, with Tv best suppressing growth of both Phytophthora spp. T. virens isolate Tv was the only isolate observed coiling around P. tropicalis mycelium and disrupted the formation of P. palmivora sporangia. Of all six isolates, only Tv reduced P. palmivora lesion expansion in a detached pod assay, reducing severity by 71%. Tv also reduced P. palmivora infection on seedlings when applied aerially at 1 × 10⁶ and 1 × 10⁸ conidia/ml, by 19% and 59%, respectively. T. virens isolate Tv is a mycoparasite, antagonizes Phytophthora in a dual plate assay, and shows antibiosis against Phytophthora spp., suggesting that multiple modes of action contribute to its ability to limit Phytophthora lesion expansion on cacao pods and seedlings.     

Changes in abundances of Alexandrium tamarense resting cysts after the tsunami caused by the Great East Japan Earthquake in Funka Bay,Hokkaido, Japan

The 2011 Great East Japan Earthquake and the subsequent huge tsunami greatly affected both human activity and the coastal marine ecosystem along the Pacific coast of Japan. The tsunami also reached Funka Bay in northern Japan and caused serious damage to the scallop cultures there, and this tsunami was believed to have affected the coastal environments in the bay. Therefore, we investigated the changes in the spatial abundance and distribution of the toxic dinoflagellates Alexandrium tamarense cysts before the tsunami (August 2010) and after the tsunami (May 2011, August 2011, May 2012 and August 2012) in the bay. Further, monthly sampling was conducted after the tsunami to identify seasonal changes of Alexandrium catenella/tamarense cysts and vegetative cells. Significant increases were observed in the populations of A. catenella/tamarense cysts, comparing the abundances before the tsunami (in August 2010; 70 ± 61 cysts g⁻¹ wet sediment) to those just after it (in May 2011; 108 ± 84 cysts g⁻¹ wet sediment), and both A. tamarense bloom (a maximum density was 1.3 × 10³ cells L⁻¹) and PSP (Paralytic Shellfish Poisoning) toxin contamination of scallops (9.4 mouse unit g⁻¹ was recorded) occurred in the bay. Seasonal sampling also revealed that the encystment of A. tamarense and the supply of the cysts to bottom sediments did not occur in the bay from September to April. These results strongly suggested that the mixing of the bottom sediments by the tsunami caused the accumulation of the toxic A. tamarense cysts in the surface of bottom sediment through the process of redeposition in Funka Bay. Moreover, this cyst deposition may have contributed to the toxic bloom formation as a seed population in the spring of 2011.     

An LED-based UV-B irradiation system for tiny organisms: System description and demonstration experiment to determine the hatchability of eggs from four Tetranychus spider mite species from Okinawa

We developed a computer-based system for controlling the photoperiod and irradiance of UV-B and white light from a 5 × 5 light-emitting diode (LED) matrix (100 × 100 mm). In this system, the LED matrix was installed in each of four irradiation boxes and controlled by pulse-width modulators so that each box can independently emit UV-B and white light at irradiances of up to 1.5 and 4.0 W m⁻², respectively, or a combination of both light types. We used this system to examine the hatchabilities of the eggs of four Tetranychus spider mite species (T. urticae, T. kanzawai, T. piercei and T. okinawanus) collected from Okinawa Island under UV-B irradiation alone or simultaneous irradiation with white light for 12 h d⁻¹ at 25 °C. Although no eggs of any species hatched under the UV-B irradiation, even when the irradiance was as low as 0.02 W m⁻², the hatchabilities increased to >90% under simultaneous irradiation with 4.0 W m⁻² white light. At 0.06 W m⁻² UV-B, T. okinawanus eggs hatched (15% hatchability) under simultaneous irradiation with white light, whereas other species showed hatchabilities <1%. These results suggest that photolyases activated by white light may reduce UV-B–induced DNA damage in spider mite eggs and that the greater UV-B tolerance of T. okinawanus may explain its dominance on plants in seashore environments, which have a higher risk of exposure to reflected UV-B even on the undersurface of leaves. Our system will be useful for further examination of photophysiological responses of tiny organisms because of its ability to precisely control radiation conditions.     

Clinical significance of serum transforming growth factor-β1 in lung cancer

Background: Transforming growth factor-β1 (TGF-β1) plays a critical role in human cancer development. Present study aimed to explore the clinical significance of serum TGF-β1 levels in patients with lung cancer and analyze the relationship between TGF-β1 and existing tumor markers for lung cancer. Methods: Serum was collected from 118 patients with lung cancer and 40 healthy volunteers. Serum TGF-β1 levels were measured by enzyme-linked immunosorbent assay (ELISA), and the association with various clinical characteristics was analyzed. The diagnostic value of TGF-β1 was assessed alone and in combination with existing tumor markers for lung cancer. Results: Serum TGF-β1 levels were significantly higher in patients with lung cancer compared to healthy volunteers [0.6 × 10⁵ (0.4 × 10⁵, 0.9 × 10⁵) pg/ml vs 0.5 × 10⁵ (0.3 × 10⁵, 0.7 × 10⁵) pg/ml, P = 0.040]. Although there was a positive correlation between serum TGF-β1 levels and advanced stages, the significant difference was not found between early stages and advanced stages (P = 0.116). The ability of serum TGF-β1 to discriminate lung cancer at a cutoff value of 79,168 pg/ml exhibited sensitivity of 30.6% and specificity of 97.5%. Serum TGF-β1 levels were correlated to cytokeratin fragment 21-1 (CYFRA21-1; R = 0.308, P = 0.020) and neuron-specific enolase (NSE; R = 0.558, P = 0.003). The diagnostic accuracy rates for the existing lung-tumor markers, as SCC, CYFRA21-1, and NSE, were increased from 20.0%, 34.6%, and 45.9% to 48.9%, 51.7%, and 54.5%, respectively by the inclusion of serum TGF-β1 levels. Conclusion: Quantification of serum TGF-β1 levels by ELISA may provide a novel complementary tool for the clinical diagnosis of lung cancer.     

Comparative studies on dry matter intake,digestibility and nitrogen metabolism between Thai native (TN) and Anglo Nubian × TN bucks

Metabolic experiments were conducted for each Thai native (TN) and Anglo Nubian–TN 50% (AN × TN) bucks, 26.5–38 kg BW and 35–52 months of age, by assigning the following concentrate diets, which had four levels of CP concentrations, T1: 14%, T2: 21%, T3: 28% and T4: 35%, on a DM basis. The animals were fed the concentrates at a rate of 1% of their BW and had ad libitum access to Paspalum plicatulum hay. As the CP level increased, digestibility of CP, N excretion in urine and N retention increased (P < 0.01). No significant differences of DM digestibility among the CP levels of diet and between the breeds of bucks were observed. The AN × TN had higher DM intake than TN (P < 0.05, 40.9 g/(kg BW^0.75 day) versus 36.0 g/(kg BW^0.75 day)), thus N intake of AN × TN was higher than that of TN (P < 0.01, 0.99 g/(kg BW^0.75 day) versus 0.90 g/(kg BW^0.75 day)). Digestibility of CP and blood urea N concentrations of TN were higher than those of AN × TN (P < 0.05, 69.8% versus 64.0% and 32.2 mg/dl versus 26.7 mg/dl, respectively). The AN × TN tended to retain more N than TN in the higher CP feeding condition of T3 (0.19 g/(kg BW^0.75 day) versus 0.11 g/(kg BW^0.75 day)) and T4 (0.25 g/(kg BW^0.75 day) versus 0.17 g/(kg BW^0.75 day)). Digestibility of NDF and ADF, and TDN of TN were higher than those of AN × TN (P < 0.05, 61.1% versus 55.9%, 49.6% versus 43.5% and 65.8% versus 62.4%, respectively). The overall mean DE was 109 kcal/(kg BW^0.75 day), and no significant difference of DE among CP levels nor breeds of bucks was observed. Thai native was superior to AN × TN in digestibility of N and fiber fractions at the maintenance level of DE, which might have overcome inferiority of TN to AN × TN in amount of N and energy intake caused by the lower DMI. It is likely that TN goats are well adapted to fodder shortage condition due to their efficient utilization of nutrients.     

Algicidal and growth-inhibiting bacteria associated with seagrass and macroalgae beds in Puget Sound,WA, USA

The algicidal and growth-inhibiting bacteria associated with seagrasses and macroalgae were characterized during the summer of 2012 and 2013 throughout Puget Sound, WA, USA. In 2012, Heterosigma akashiwo-killing bacteria were observed in concentrations of 2.8 × 10⁶ CFU g⁻¹ wet in the outer organic layer (biofilm) on the common eelgrass (Zostera marina) in north Padilla Bay. Bacteria that inhibited the growth of Alexandrium tamarense were detected within the biofilm formed on the eelgrass canopy at Dumas Bay and North Bay at densities of ∼10⁸ CFU g⁻¹ wet weight. Additionally, up to 4100 CFU mL⁻¹ of algicidal and growth-inhibiting bacteria affecting both A. tamarense and H. akashiwo were detected in seawater adjacent to seven different eelgrass beds. In 2013, H. akashiwo-killing bacteria were found on Z. marina and Ulva lactuca with the highest densities of ∼10⁸ CFU g⁻¹ wet weight at Shallow Bay, Sucia Island. Bacteria that inhibited the growth of H. akashiwo and A. tamarense were also detected on Z. marina and Z. japonica at central Padilla Bay. Heterosigma akashiwo cysts were detected at a concentration of 3400 cysts g⁻¹ wet weight in the sediment from Westcott Bay (northern San Juan Island), a location where eelgrass disappeared in 2002. These findings provide new insights on the ecology of algicidal and growth-inhibiting bacteria, and suggest that seagrass and macroalgae provide an environment that may influence the abundance of harmful algae in this region. This work highlights the importance of protection and restoration of native seagrasses and macroalgae in nearshore environments, in particular those regions where shellfish restoration initiatives are in place to satisfy a growing demand for seafood.     

Inactivation of IL-6 and soluble IL-6 receptor by neutrophil derived serine proteases in cystic fibrosis

The ability of IL-6 to signal via both membrane bound and soluble receptors is thought to explain the capacity of this cytokine to act in both the initiation and resolution of acute inflammatory responses. In cystic fibrosis (CF), poorly resolved neutrophillic inflammation of the lungs is a primary cause of morbidity and mortality. Expression of IL-6 has been reported to be low in CF lung secretions, despite ongoing inflammation, but the status of soluble IL-6 receptor (sIL-6R) in these patients is unknown. We hypothesised that sIL-6R may be an important potentiator of IL-6 activity in CF associated lung disease. IL-6, sIL-6R and sgp130 (a natural antagonist of responses mediated by the sIL-6R) were analysed by ELISA and Western blot in bronchoalveolar lavage fluid (BALF) from 28 paediatric CF patients and nine non-CF controls. Total cell counts in CF were four fold higher compared to controls (median: 1.4 × 10⁶ cells/ml v. 0.35 × 10⁶ cells/ml in controls) (p < 0.001) and the infiltrate was dominated by neutrophils which were elevated by 89 fold (0.62 × 10⁶ cells/ml v. 0.007 × 10⁶ cells/ml in controls) (p < 0.001). Other markers of inflammation such as IL-8 and MCP-1 were elevated 17.5 and 3.8 fold respectively (IL-8; median: 1122 pg/ml v. 64 pg/ml in controls, p < 0.01 and MCP-1; median: 692 pg/ml v. 182 pg/ml in controls, p < 0.05). IL-6, although present in 23/32 CF BALF specimens compared to 1/9 controls (p < 0.01), was weakly expressed (median: 50 pg/ml). Expression of sIL-6R and sgp130 in CF was no different to control patients. We tested whether weak expression of all three molecules was due to degradation by CF BALF. Degradative activity was observed in association with BALF elastase activity and could be specifically blocked by serine protease inhibitors. Degradation of sIL-6R by purified serine proteases (elastase, cathepsin G and proteinase 3) was also observed leading to a loss of trans-signalling activity. Interestingly, sIL-6R was protected from proteolysis by interaction with IL-6. Our data identify and define a novel protease mediated deficiency of IL-6 signalling in the CF lung.     

Effect of temperature and host species on parasitism,development time and sex ratio of the egg parasitoid Trichogrammatoidea lutea Girault (Hymenoptera: Trichogrammatidae)

The developmental biology of Trichogrammatoidea lutea Girault (Hymenoptera: Trichogrammatidae) was studied at six constant temperatures (18, 21, 24, 27, 30 and 35 °C) on eggs of three lepidopteran host species: Helicoverpa armigera (Hübner) (Noctuidae), Chilo partellus (Swinhoe) (Crambidae) and Cadra cautella (Walker) (Pyralidae). T. lutea did not complete development at 35 °C on any of the three host species. Parasitism levels were highest on H. armigera at 27 °C (58%), C. cautella at 27 and 30 °C (31% and 28%) and C. partellus between 24 and 30 °C (13–17%). Realized progeny of T. lutea per parasitized host egg was influenced by host size. The number of progeny of T. lutea per parasitized host egg was highest on H. armigera, followed by C. partellus and lowest on C. cautella. The sex ratio was female biased on C. partellus, female biased on C. cautella with the exception of 21 °C and close to 1:1 on H. armigera. The rate of development from egg to pupa and egg to adult was fastest on H. armigera and slowest on C. partellus. Lower thresholds for development and degree days (DD) of T. lutea from egg to adult were 12.8 °C and 105.4 DD on H. armigera, 11.3 °C and 141.6 DD on C. partellus and 12.9 °C and 118.2 DD on C. cautella, respectively. Based on these results, H. armigera is the most suitable host for mass rearing of T. lutea for biological control of Lepidoptera pests because of the relatively high parasitism levels, short development time, greater clutch size and balanced sex ratio. C. cautella may also be used although longer exposure times might be required due to lower parasitism levels.     

Isolation and identification of gastrointestinal microbiota from the short-nosed fruit bat Cynopterus brachyotis brachyotis

Studies on the microbial ecology of gut microbiota in bats are limited and such information is necessary in determining the ecological significance of these hosts. Short-nosed fruit bats (Cynopterus brachyotis brachyotis) are good candidates for microbiota studies given their close association with humans in urban areas. Thus, this study explores the gut microbiota of this species from Peninsular Malaysia by means of biochemical tests and 16S rRNA gene sequences analysis. The estimation of viable bacteria present in the stomach and intestine of C. b. brachyotis ranged from 3.06 × 10¹⁰ to 1.36 × 10¹⁵ CFU/ml for stomach fluid and 1.92 × 10¹⁰ to 6.10 × 10¹⁵ CFU/ml for intestinal fluid. A total of 34 isolates from the stomach and intestine of seven C. b. brachyotis were retrieved. A total of 16 species of bacteria from eight genera (Bacillus, Enterobacter, Enterococcus, Escherichia, Klebsiella, Pantoea, Pseudomonas and Serratia) were identified, Enterobacteriaceae being the most prevalent, contributing 12 out of 16 species isolated. Most isolates from the Family Enterobacteriaceae have been reported as pathogens to humans and wildlife. With the possibility of human wildlife transmission, the findings of this study focus on the importance of bats as reservoirs of potential bacterial pathogens.     

Different life cycle strategies of the dinoflagellates Fragilidium duplocampanaeforme and its prey Dinophysis acuminata may explain their different susceptibilities to the infection by the parasite Parvilucifera infectans

Some marine dinoflagellates form ecdysal cyst (=temporary cysts) as part of their life cycle or under unfavorable growth conditions. Whether the dinoflagellates form ecdysal cysts or not may influence susceptibility to parasitism. In this study, parasite prevalence relative to inoculum size of the parasitoid Parvilucifera infectans zoospores for two dinoflagellate hosts (i.e., Fragilidium duplocampanaeforme and Dinophysis acuminata), which have different life cycle strategies, was examined. Further, susceptibility of cysts to parasitism, encystment signal, duration of encystments, and effects of induced encystment on diel periodicity, using ecdysal cyst-forming F. duplocampanaeforme were explored. The percent hosts infected by P. infectans plotted as a function of inoculum size showed a sharp increase to a maximum in D. acuminata, but a gradual linear rise in F. duplocampanaeforme: while the parasite prevalence in D. acuminata increased to a maximum of 78.8 (±2.4%) by a zoospore:host ratio of 20:1, it in F. duplocampanaeforme only reached 8.9 (±0.3%), even at a zoospore:host ratio of 120:1. In F. duplocampanaeforme, infections were observed only in the vegetative cells and not observed in ecdysal cysts. When exposed to live, frozen, and sonicated zoospores and zoospore filtrate, F. duplocampanaeforme formed ecdysal cysts only when exposed to live zoospores, suggesting that temporary cyst formation in the dinoflagellate resulted from direct contact with zoospores. When the Parvilucifera zoospores attacked and struggled to penetrate F. duplocampanaeforme through its flagellar pore, the Fragilidium cell shed all thecal plates, forming a ‘thecal cloud layer’, in which the zoospores were caught and immobilized and thus could not penetrate anymore. The duration (35 ± 1.8 h) of ecdysal cysts induced with addition of zoospores was significantly longer than that (15 ± 0.8 h) of normally formed cysts (i.e., without addition of zoospores), thereby resulting in delayed growth as well as influencing the pattern of diel periodicity. The results from this study suggest that in addition to the classical predator-prey interaction and allelopathic interaction, parasitism and its accompanying defense can make the food web dynamics much more complicated than previously thought.