;hycomyces: Interference Between the Light Growth Response nd the Avoidance Response

Phycomyces sporangiophores showl a growth response to a light stimus and an avoidance bending response to a physical barrier. A bluie-light stimnlluts Imninisteredl in conjunction with a barrier interferes with the avoidance bending sponse. This interference begins ifter a latency of abotit 3 minultes atndt continues a period of 4 to 5 minutes.     

Top 20 environmental weeds for classical biological control in Europe: a review of opportunities, regulations and other barriers to adoption

Classical biological control remains the only tool available for permanent ecological and economic management of invasive alien species that flourish through absence of their co‐evolved natural enemies. As such, this approach is recognized as a key tool for alien species management by the Convention on Biological Diversity (CBD), the European and Mediterranean Plant Protection Organization (EPPO) and the European Strategy on Invasive Alien Species (ESIAS). Successful classical biological control programmes abound around the world, despite disproportionate attention being given to occasional and predictable non‐target impacts. Despite more than 130 case histories in Europe against insect pests, no exotic classical biological control agent has been released in the EU against an alien invasive weed. This dearth has occurred in the face of increasing numbers of exotic invasive plants being imported and taking over National Parks, forests and amenity areas in this region, as well as a global increase in the use of classical biological control around the world. This paper reviews potential European weed targets for classical biological control from ecological and socioeconomic perspectives using the criteria of historical biological control success, taxonomic isolation from European native flora, likely availability of biological control agents, invasiveness outside Europe and value to primary industry and horticulture (potential for conflicts of interest). We also review why classical biological control of European exotic plants remains untested, considering problems of funding and public perception. Finally, we consider the regulatory framework that surrounds such biological control activities within constituent countries of the EU to suggest how this approach may be adopted in the future for managing invasive exotic weeds in Europe.     

The efficiency and condition of oysters and macroalgae used as biological filters of shrimp pond effluent

Current shrimp pond management practices generally result in elevated concentrations of nutrients, suspended solids, bacteria and phytoplankton compared with the influent water. Concerns about adverse environmental impacts caused by discharging pond effluent directly into adjacent waterways have prompted the search for cost‐effective methods of effluent treatment. One potential method of effluent treatment is the use of ponds or raceways stocked with plants or animals that act as natural biofilters by removing waste nutrients. In addition to improving effluent water quality prior to discharge, the use of natural biofilters provides a method for capturing otherwise wasted nutrients. This study examined the potential of the native oyster, Saccostrea commercialis (Iredale and Roughley) and macroalgae, Gracilaria edulis (Gmelin) Silva to improve effluent water quality from a commercial Penaeus japonicus (Bate) shrimp farm. A system of raceways was constructed to permit recirculation of the effluent through the oysters to maximize the filtration of bacteria, phytoplankton and total suspended solids. A series of experiments was conducted to test the ability of oysters and macroalgae to improve effluent water quality in a flow‐through system compared with a recirculating system. In the flow‐through system, oysters reduced the concentration of bacteria to 35% of the initial concentration, chlorophyll a to 39%, total particulates (2.28–35.2 µm) to 29%, total nitrogen to 66% and total phosphorus to 56%. Under the recirculating flow regime, the ability of the oysters to improve water quality was significantly enhanced. After four circuits, total bacterial numbers were reduced to 12%, chlorophyll a to 4%, and total suspended solids to 16%. Efforts to increase biofiltration by adding additional layers of oyster trays and macroalgae‐filled mesh bags resulted in fouling of the lower layers causing the death of oysters and senescence of macroalgae. Supplementary laboratory experiments were designed to examine the effects of high effluent concentrations of suspended particulates on the growth and condition of oysters and macroalgae. The results demonstrated that high concentrations of particulates inhibited growth and reduced the condition of oysters and macroalgae. Allowing the effluent to settle before biofiltration improved growth and reduced signs of stress in the oysters and macroalgae. A settling time of 6 h reduced particulates to a level that prevented fouling of the oysters and macroalgae.     

Conception rates in European fallow does (Dama dama dama) following intrauterine insemination with frozen-thawed semen from Mesopotamian fallow (Dama dama mesopotamica) and crossbred (Dama dama dama x Dama dama mesopotamica) bucks

Ninety eight parous fallow does received laparoscopic intrauterine insemination of frozen-thawed semen at one of 2 fixed intervals following oestrus synchronisation treatment. Semen was collected from a Mesopotamian (Dama dama mesopotamica) and a crossbred (F1) (Dama dama dama x Dama dama mesopotamica) fallow buck. Does were inseminated at either 56 or 66 hours after the removal of an intravaginal controlled internal drug releasing device. Eighty eight does received a single straw of frozen-thawed semen containing a total of 50 x 10(6) spermatozoa, while the remaining 10 received split straws containing 25 x 10(6) spermatozoa. Overall, the use of F1 semen containing 50 x 10(6) spermatozoa resulted in a 68% (17/25) conception rate compared with the Mesopotamian semen, which resulted in a 41% (26/63) conception rate. Conceptions were also achieved using 25 x 10(6) spermatozoa of either Mesopotamian or F1 semen (3/8 versus 2/2, respectively). Overall, the conception rate was higher for F1 than Mesopotamian semen (P less than 0.025) and there was a significant interaction with time of insemination (P less than 0.05); for F1 semen there was no difference in conception rate at the 2 insemination times, but for Mesopotamian semen conception was significantly higher (P less than 0.005) following insemination at 66 hours than at 56 hours.     

Comparison of the odds of isolation, genotypes, and in vivo production of major toxins by Clostridium perfringens obtained from the gastrointestinal tract of dairy cows with hemorrhagic bowel syndrome or left-displaced abomasum

OBJECTIVE: To compare the frequency of isolation, genotypes, and in vivo production of major lethal toxins of Clostridium perfringens in adult dairy cows affected with hemorrhagic bowel syndrome (HBS) versus left-displaced abomasum (LDA). DESIGN: Case-control study. ANIMALS: 10 adult dairy cattle with HBS (cases) and 10 adult dairy cattle with LDA matched with cases by herd of origin (controls). PROCEDURE: Samples of gastrointestinal contents were obtained from multiple sites during surgery or necropsy examination. Each sample underwent testing for anaerobic bacteria by use of 3 culture methods. The genotype of isolates of C. perfringens was determined via multiplex polymerase chain reaction assay. Major lethal toxins were detected by use of an ELISA. Data were analyzed with multivariable logistic regression and chi2 analysis. RESULTS: C. perfringens type A and type A with the beta2 gene (A + beta2) were the only genotypes isolated. Isolation of C. perfringens type A and type A + beta2 was 6.56 and 3.3 times as likely, respectively, to occur in samples from cattle with HBS than in cattle with LDA. Alpha toxin was detected in 7 of 36 samples from cases and in 0 of 32 samples from controls. Beta2 toxin was detected in 9 of 36 samples from cases and 0 of 36 samples from controls. CONCLUSIONS AND CLINICAL RELEVANCE: C. perfringens type A and type A + beta2 can be isolated from the gastrointestinal tract with significantly greater odds in cattle with HBS than in herdmates with LDA. Alpha and beta2 toxins were detected in samples from cows with HBS but not from cows with LDA.