Penaeus monodon larvae can be protected from Vibrio harveyi infection by pre‐emptive treatment of a rearing system with antagonistic or non‐antagonistic bacterial probiotics

This study shows that the disease resistance and survival rate of Penaeus monodon in a larval rearing systems can be enhanced by supplementing with antagonistic or non‐antagonistic probiotics. The antagonistic mode of action of Pseudomonas MCCB 102 and MCCB 103 against vibrios was demonstrated in larval mesocosm with cultures having sufficient concentration of antagonistic compounds in their culture supernatant. Investigations on the antagonistic properties of Bacillus MCCB 101, Pseudomonas MCCB 102 and MCCB 103 and Arthrobacter MCCB 104 against Vibrio harveyi MCCB 111 under in vitro conditions revealed that Pseudomonas MCCB 102 and MCCB 103 were inhibitory to the pathogen. These inhibitory properties were further confirmed in the larval rearing systems of P. monodon. All these four probionts significantly improved larval survival in long‐term treatments as well as when challenged with a pathogenic strain of V. harveyi MCCB 111. We could demonstrate that Pseudomonas MCCB 102 and MCCB 103 accorded disease resistance and a higher survival rate in P. monodon larval rearing systems through active antagonism of vibrios, whereas Bacillus MCCB 101 and Arthrobacter MCCB 104 functioned as probiotics through immunostimulatory and digestive enzyme‐supporting modes of action.     

Development of an efficient protocol for plant regeneration from nodal explants of recalcitrant bamboo (Bambusa arundinacea Retz. Willd) and assessment of genetic fidelity by DNA markers

The present study describes an efficient method for in vitro plant regeneration in B. arundinacea through axillary shoot bud proliferation. Nodal explants were excised, cultured on MS medium containing different concentrations of 6-benzylaminopurine (BAP), kinetin (KIN) (0.5–5.0 mg l^?1) alone and/or in combinations with KIN/BAP (0.5 mg l^?1). The highest frequency (91.5 %) of multiple shoot bud induction with maximum number of shoots (85 shoots/explant) was noticed on MS medium + 3.0 mg l^?1 BAP + 0.5 mg l^?1 KIN. The regenerated multiple shoots were elongated on MS medium + 4.0 mg l^?1 KIN + 2.0 mg l^?1 gibberellic acid (GA₃) with maximum shoot length (4.9 cm). The elongated shoots were transferred to MS medium containing indole-3 butyric acid (IBA; 0.5–5.0 mg l^?1) alone and/or in combination with 0.5 mg l^?1 KIN and BAP. Highest frequency of rooting (75 %) was obtained on half-strength MS medium + 2.0 mg l^?1 IBA + 0.5 mg l^?1 KIN. After hardening, the plantlets were shifted to the green house and subsequently established in the field conditions with 90 % survival rate. random amplified polymorphic DNA (RAPD) markers were used to evaluate the genetic stability of the regenerants. RAPD profiles generated from the regenerated plants were found to be monomorphic, similar to the control. Results confirmed that the regenerated plants were true-to-type in nature and the developed micropropagation protocol could be used for large scale plant production of B. arundinacea.     

Properties of the immunosuppressive factor induced by murine cytomegalovirus

Murine cytomegalovirus infection of spleen cultures induced the production of a small (less than 10,000 molecular weight) immunosuppressive factor (VISF), which suppressed concanavalin-A mitogenesis in fresh mouse spleen cells, and in fresh human peripheral blood leukocytes. The factor did not affect the growth of two murine T-cell lines or of mouse fibroblasts. A similar factor was also found in the serum of infected mice, at the time of maximum immune suppression. The properties of VISF indicate that the mechanism of MCMV immune suppression is different from that caused by several other viruses which are important in human and veterinary medicine.     

Transfection of non-susceptible cells with Ovis aries recombinant lymphocyte function-associated antigen 1 renders susceptibility to Mannheimia haemolytica leukotoxin

Mannheimia haemolytica is an important etiological agent of pneumonia in domestic sheep (DS, Ovis aries). Leukotoxin (Lkt) produced by this organism is the principal virulence factor responsible for the acute inflammation and lung injury characteristic of M. haemolytica caused disease. Previously, we have shown that the leukocyte-specific integrins, beta(2) integrins, serve as the receptor for Lkt. Although it is certain that CD18, the beta subunit of beta(2) integrins, mediates Lkt-induced cytolysis of leukocytes, it is not clear whether CD18 of all three beta(2) integrins, LFA-1, Mac-1 and CR4, mediates Lkt-induced cytolysis of DS leukocytes. Since polymorphonuclear leukocytes, which express all three beta(2) integrins, are the leukocyte subset that is most susceptible to Lkt, we hypothesized that all three beta(2) integrins serve as the receptor for Lkt. The objective of this study was to determine whether DS LFA-1 serves as a receptor for M. haemolytica Lkt. We cloned the cDNA for DS CD11a, the alpha subunit of LFA-1, and co-transfected it along with the previously cloned cDNA for DS CD18, into a Lkt-non-suceptible cell line. Transfectants stably expressing DS LFA-1 were bound by Lkt. More importantly, Lkt lysed the DS LFA-1 transfectants in a concentration-dependent manner. Pre-incubation of Lkt with a Lkt-neutralizing monoclonal antibody (MAb), or pre-incubation of transfectants with MAbs specific for DS CD11a or CD18, inhibited Lkt-induced cytolysis of the transfectants. Exposure of LFA-1 transfectants to low concentrations of Lkt resulted in elevation of intracellular [Ca(2+)](i). Taken together, these results indicate that DS LFA-1 serves as a receptor for M. haemolytica Lkt.     

Molecular fingerprinting of Riemerella anatipestifer by repetitive sequence PCR.

Riemerella anatipestifer is a gram-negative rod-shaped bacterium associated with epizootic infections in poultry. A total of 35 R. anatipestifer isolates including the type strain ATCC11845T, reference and field strains for 18 different serotypes were characterized by repetitive sequence based-PCR (rep-PCR) with outwardly-directed primers based on the repetitive extragenic palindromic (REP) consensus sequence. This technique was applied by using either extracted genomic DNA or preparation of whole bacterial cells harvested directly from plate cultures. Rep-PCR discriminated the R. anatipestifer isolates into 19 electrophoretic types. DNA fingerprints obtained from rep-PCR of extracted genomic DNA or from preparations of whole cells yielded comparable patterns. Substantial variation was seen among the rep-PCR fingerprints of different serotypes. Moreover, different polymorphisms of the rep-PCR fingerprints were evident among epidemiologically unrelated isolates of the same serotype. These results suggest the presence of repetitive extragenic palindromic-like elements within the genome of R. anatipestifer that can be used in some isolates to discriminate between different strains belonging to the same serotype. Rep-PCR may serve as a useful molecular tool for subtyping R. anatipestifer isolates for epidemiologic investigations. The whole cell procedure offers the advantage of ease of performance requiring only small quantities of cells.     

Evaluation of bermuda and paspalum grass types for urban landscapes under saline water irrigation

In the arid regions, turfgrass cover is an integral part of landscape to protect the soil from erosion, enhance the aesthetic value, and improve the microclimate. The salinity and the scarcity of fresh water of the arid region are the major challenging factors in turfgrass production. Therefore, the need for salt tolerant turfgrass with functional quality is necessary to improve the turf performance. The detrimental effects of salinity include growth suppression, and lowered osmotic potential ultimately leading to firing of the leaf blades. In this context, the study was undertaken to determine the relative salt tolerance and growth response of turfgrass genotypes in order to recommend turfgrass cultivars that can tolerate high salinity irrigation and maintain excellent visual and functional qualities under United Arab Emirates (UAE) condition. The paspalum cultivars maintained the highest succulence percentage compared to the bermudagrass cultivars under enhanced salinity levels. The shoots count, fresh weight (FW), and dry weight (DW) were found highest in paspalum types. The chlorophyll a, chlorophyll b and the total chlorophyll content was found higher in bermuda grass types under high salinity levels. The bermudagrass cultivars showed significantly higher carotenoids, anthocyanins and proline compared to the paspalum types under salt stress condition. In the case of princess 77 and Yukon, an inherently high amount of proline was recorded which confirmed an increase up to 10,000 ppm and drastically declined beyond this concentration. Sea Dwarf paspalum and Sea Isle 2000 maintained uniformity in the proline level at all levels of salinity without significant variation. These findings point to the fact that both paspalum and bermuda types exhibited varied responses to different physiological and biochemical parameters under the saline conditions. Paspalum types have an edge over the bermudagrass in terms of shoot density, which is a potential factor in determining the high-quality turfs. Bermudagrass types can be applied in lower salinity conditions based on the responses as evidenced from the present results.     

Dynamics of Clay Particles in Non-vegetated Stormwater Biofilters

Stormwater biofilters manage quantity and quality of urban stormwater runoff. Particulate solids from natural and anthropogenic sources accumulate on paved surfaces and eventually reach receiving waters. Retention of suspended solids in stormwater management systems ensures the quality of stormwater runoff to water resources. Stormwater biofilters are similar in most of design parameters to sand filters employed in water treatment systems. The understanding and design of stormwater biofilters are often based on generic models of sand filters. Unlike water treatment sand filters, which are continuously fed, stormwater biofilters operate intermittently with spontaneously alternating wetting and drying cycles. This results in dynamic pollutant removal pattern that employs different mechanisms during and across rainfall events. As such, pilot scale biofilter columns fabricated with a layer of organic material were operated. Removal of suspended solids was very dynamic, where impact of age of filter, antecedent dry days, and inflow quality varied during and across events. Flush of retained solids and filter material occurred during the stabilisation period during each event while very high removal percentages (more than 90%) were observed after stabilisation, during an event. Clogging was not observed due to re-entrainment, re-distribution, and flush of retained solids during intermittent wetting and drying cycles.     

Cytochrome oxidase gene sequencing reveals channel catfish ovary cell line is contaminated with brown bullhead cells

The channel catfish (Ictalurus punctatus, Rafinesque) ovary (CCO) cell line is the standard cell line used for channel catfish diagnostics. Next‐gen sequencing studies of a virus cultured in the CCO cells revealed mitochondrial sequences matching those of brown bullhead (Ameiurus nebulosus, Lesueur). Therefore, we systematically performed partial cytochrome oxidase 1 gene sequencing of several sources of the CCO cell line and all matched the brown bullhead and not the channel catfish.