Biofilm development within a larval rearing tank of the tropical rock lobster, Panulirus ornatus

The role of bacterial biofilms in disease processes is becoming increasingly recognised in both clinical and environmental settings. Biofilm development within a rearing tank of the tropical rock lobster Panulirus ornatus was studied to evaluate if the biofilm is a reservoir for potentially pathogenic bacteria that cause mass larval mortalities. Within a 5000 L larval rearing tank, fiberglass microscope slides were systematically distributed during a standard rearing attempt to assess biofilm development. Culture-based counts for two media types, TCBS and Marine Agar (MA), demonstrated increased bacterial densities until days 11 and 13 respectively. For both media types, a drop in the plate counts was followed by a subsequent increase towards the end of the experiment. Scanning electron microscopy (SEM) confirmed that cell densities decreased between days 13 and 17, most likely due to sloughing of the biofilm into the water column. SEM images revealed distinct changes in dominant morphologies reflecting a succession of bacterial populations. A dynamic succession of microbial species during biofilm development was also demonstrated using denaturing gradient gel electrophoresis (DGGE) profiling of bacterial 16S rRNA genes in combination with statistical ordination analysis. Prominent changes in the DGGE profiles coincided with the decrease in bacterial numbers observed by SEM and plating on MA between days 13 and 17. Fluorescence in situ hybridization (FISH) identified -Proteobacteria as being numerically abundant in the biofilm. This was supported by results from DGGE analysis, which retrieved only sequences affiliated with - and γ-Proteobacteria. DGGE bands affiliated with Vibrio became dominant towards the end of the larval run (days 21 to 24). A Vibrio harveyi strain isolated from the biofilm late in the larval rearing trial (day 24) demonstrated increased larval mortality in small scale phyllosoma survival studies. The detection of Vibrionaceae at the end of the larval trial coincided with mass phyllosoma mortality and show that the biofilm is a reservoir for potentially pathogenic bacteria.     

A serological survey for antibodies against foot-and-mouth disease virus (FMDV) in domestic pigs during outbreaks in Kenya

Foot-and-mouth disease (FMD) is endemic in Kenya and has been well studied in cattle, but not in pigs, yet the role of pigs is recognised in FMD-free areas. This study investigated the presence of antibodies against FMD virus (FMDV) in pigs sampled during a countrywide random survey for FMD in cattle coinciding with SAT 1 FMDV outbreaks in cattle. A total of 191 serum samples were collected from clinically healthy pigs in 17 districts. Forty-two of the 191 sera were from pigs vaccinated against serotypes O/A/SAT 2 FMDV. Antibodies against FMDV non-structural proteins were found in sera from 30 vaccinated and 71 non-vaccinated pigs, altogether 101/191 sera (53 %), and 91 % of these (92/101) also had antibodies measurable by serotype-specific ELISAs, predominantly directed against SAT 1 with titres of 10–320. However, only five high titres against SAT 1 in vaccinated pigs were confirmed by virus neutralisation test (VNT). Due to high degree of agreement between the two ELISAs, it was concluded that positive pigs had been infected with FMDV. Implications of these results for the role of pigs in the epidemiology of FMD in Kenya are discussed, and in-depth studies are recommended.     

Changes of the Levels of Blood NO and TNF-α Concentrations in Water Buffaloes and Goats Infected with Fasciola hepatica

Changes of concentrations were studied in water buffaloes and goats infected with Fasciola he-patica on blood NO(nitric oxide) and TNF-α(tumor necrosis factor-α). Twenty healthy male castrated waterbuffaloes of 2 - 3 years old and weighing 300 - 500 kg as well as six goats were confirmed free of fasciolosis byfecal examination and Dot-ELISA. Two studies were conducted using the water buffaloes. In the first experi-ment, 8 water buffaloes were randomly divided into control group (n=3) and infection group (n=5). Eachbuffalo in the infected group received orally 60 metacercariae of F. hepatica per day for 20 days (total 1 200metacercariae) to produce a chronic infection. In the second experiment, 12 water buffaloes were randomly di-vided into infected (n=9) and control group (n=3). Each buffalo in the infected group was given a singleoral dose of 1 600 metacercariae to produce an acute infection. The 6 goats were randomly divided into two in-fected groups and a control group. The sheep in two infections received a single oral dose of 200 and 500 meta-cercariae respectively, the control group remained uninfected. Blood NO and TNF-α concentrations of the testanimals were measured by a reductive enzyme assay and RIA, respectively. Blood NO concentration in bothacutely and chronically infected water buffaloes progressively increased from week 3 post-infection and was sig-nificantly greater than that of the control group (P＜0.05) at the 5th week (acute infection) and 7th week(chronic infection), and remaining at higher concentration for the remaining period of the studies. BloodTNF-αt concentrations in both chronically and acutely infected water buffaloes also increased after infection. Inthe goat experiment, plasma NO concentrations in both infection groups increased from week 3 after infection,and remained higher than that of the control group until the end of the experiment. TNF-α concentrations ingoats in infection group 1 and 2 gradually increased after infection and were significantly greater than those ofthe control group from the 9th to 11th week and from the 11th to 15th week respectively.     

Toward direct measurement of atmospheric nucleation

Atmospheric aerosol formation is known to occur almost all over the world, and the importance of these particles to climate and air quality has been recognized. Although almost all of the processes driving aerosol formation take place below a particle diameter of 3 nanometers, observations cover only larger particles. We introduce an instrumental setup to measure atmospheric concentrations of both neutral and charged nanometer-sized clusters. By applying the instruments in the field, we come to three important conclusions: (i) A pool of numerous neutral clusters in the sub-3 nanometer size range is continuously present; (ii) the processes initiating atmospheric aerosol formation start from particle sizes of approximately 1.5 nanometers; and (iii) neutral nucleation dominates over the ion-induced mechanism, at least in boreal forest conditions.     

Resistance to an herbivore through engineered cyanogenic glucoside synthesis

The entire pathway for synthesis of the tyrosine-derived cyanogenic glucoside dhurrin has been transferred from Sorghum bicolor to Arabidopsis thaliana. Here, we document that genetically engineered plants are able to synthesize and store large amounts of new natural products. The presence of dhurrin in the transgenic A. thaliana plants confers resistance to the flea beetle Phyllotreta nemorum, which is a natural pest of other members of the crucifer group, demonstrating the potential utility of cyanogenic glucosides in plant defense.