Movement of Xanthomonas campestris pv. vitians in the stems of lettuce and seed contamination

Xanthomonas campestris pv. vitians , the causal agent of bacterial leaf spot of lettuce (BLS), can be seedborne, but the mechanism by which the bacteria contaminates and/or infects lettuce seed is not known. In this study, the capacity of X. campestris pv. vitians to enter and translocate within the vascular system of lettuce plants was examined. The stems of 8- to 11-week-old lettuce plants were stab-inoculated, and movement of X. campestris pv. vitians was monitored at various intervals. At 4, 8, 12 and 16 h post-inoculation (hpi), X. campestris pv. vitians was recovered from 2 to 10 cm above (depending on stem length) and 2 cm below the inoculation site. Xanthomonas campestris pv. vitians was also recovered from surface-disinfested stem sections of spray-inoculated plants. Together, these results are consistent with X. campestris pv. vitians invading and moving systemically within the vascular system of lettuce plants. To investigate the mechanism of seed contamination, lettuce plants at the vegetative stage of growth were spray-inoculated with X. campestris pv. vitians and allowed to develop BLS. Seed collected from these plants had a 2% incidence of X. campestris pv. vitians external colonization, but no bacteria were recovered from within the seed.     

Growth and morphologic response of rumen methanogenic archaea and bacteria to cashew nut shell liquid and its alkylphenol components

The growth and morphology of rumen methanogenic archaea (15 strains of 10 species in 5 genera, including 7 strains newly isolated in the present study) and bacteria (14 species in 12 genera) were investigated using unsupplemented in vitro pure cultures and cultures supplemented with cashew nut shell liquid (CNSL) and its phenolic compound components, anti-methanogenic agents for ruminant animals. Growth of most of the methanogens tested was inhibited by CNSL and alkylphenols at different concentrations ranging from 1.56 to 12.5 μg/ml. Of the alkylphenols tested, anacardic acid exhibited the most potent growth inhibition. Three gram-negative bacterial species involved in propionate production were resistant to CNSL and alkylphenols (>50 μg/ml). All the methanogens and bacteria that were sensitive to CNSL and alkylphenols exhibited altered morphology; disruption of the cell surface was notable, possibly due to surfactant activity of the tested materials. Cells division was inhibited in some organisms, with cell elongation and unclear septum formation observed. These results indicate that CNSL and alkylphenols, particularly anacardic acid, inhibit both rumen bacteria and methanogens in a selective manner, which could help mitigate rumen methane generation.     

Identification of the core rumen bacterial taxa and their population dynamics during the fattening period in Japanese Black cattle

The rumen microbiota comprises a vast range of bacterial taxa, which may affect the production of high-quality meat in Japanese Black cattle. The aim of this study was to identify core rumen microbiota in rumen fluid samples collected from 74 Japanese Black cattle raised under different dietary conditions using 16S rRNA gene amplicon sequencing. In the rumen of fattening Japanese Black cattle, 10 bacterial taxa, showing >1% average relative abundance and >95% prevalence, irrespective of the dietary conditions and the fattening periods, were identified as the core rumen bacterial taxa, which accounted for approximately 80% of the rumen microbiota in Japanese Black cattle. Additionally, population dynamics of the core rumen bacterial taxa revealed two distinct patterns: Prevotella spp. and unclassified Bacteroidales decreased in the mid-fattening period, whereas unclassified Clostridiales, unclassified Ruminococcaceae, Ruminococcus spp., and unclassified Christensenellaceae increased during the same period. Therefore, the present study reports the wide distribution of the core rumen bacterial taxa in Japanese Black cattle, and the complementary nature of the population dynamics of these core taxa, which may ensure stable rumen fermentation during the fattening period.     

Effects of Crop Rotation and Irrigation on Verticillium dahliae Microsclerotia in Soil and Wilt in Cauliflower

ABSTRACT Experiments were conducted in field plots to evaluate the effects of broccoli residue on population dynamics of Verticillium dahliae in soil and on Verticillium wilt development on cauliflower under furrow and subsurface-drip irrigation and three irrigation regimes in 1994 and 1995. Treatments were a factorial combination of three main plots (broccoli crop grown, harvested, and residue incorporated in V.dahliae-infested plots; no broccoli crop or residue in infested plots; and fumigated control plots), two subplots (furrow and subsurface-drip irrigation), and three sub-subplots (deficit, moderate, and excessive irrigation regimes) arranged in a split-split-plot design with three replications. Soil samples collected at various times were assayed for V. dahliae propagules using the modified Anderson sampler technique. Incidence and severity of Verticillium wilt on cauliflower were assessed at 7- to 10-day intervals beginning a month after cauliflower transplanting and continuing until harvest. Number of propagules in all broccoli plots declined significantly (P < 0.05) after residue incorporation and continued to decline throughout the cauliflower season. The overall reduction in the number of propagules after two broccoli crops was approximately 94%, in contrast to the fivefold increase in the number of propagules in infested main plots without broccoli after two cauliflower crops. Disease incidence and severity were both reduced approximately 50% (P < 0.05) in broccoli treatments compared with no broccoli treatments. Differences between furrow and subsurface-drip irrigation were not significant, but incidence and severity were significantly (P < 0.05) lower in the deficit irrigation regime compared with the other two regimes. Abundance of microsclerotia of V. dahliae on cauliflower roots about 8 weeks after cauliflower harvest was significantly (P < 0.05) lower in treatments with broccoli compared with treatments without broccoli. Rotating broccoli with cauliflower and incorporating broccoli residues into the soils is a novel means of managing Verticillium wilt on cauliflower and perhaps on other susceptible crops. This practice would be successful regardless of the irrigation methods or regimes followed on the susceptible crops.     

Induction of Systemic Resistance in Cucumber against Several Diseases by Plant Growth-promoting Fungi: lignification and Superoxide Generation

Five fungal isolates (Trichoderma, Fusarium, Penicillium, Phoma and a sterile fungus) from zoysiagrass rhizosphere that promote plant growth were tested for their ability to induce systemic resistance in cucumber plants against Colletotrichum orbiculare. Roots of cucumber plants were treated with these fungal isolates using barley grain inocula (BGI), mycelial inocula (MI) or culture filtrate (CF). Most isolate/inoculum form combinations significantly reduced the disease except BGI of Trichoderma. These fungal isolates were also evaluated for induction of systemic resistance against bacterial angular leaf spot and Fusarium wilt by treatment with BGI. Penicillium, Phoma and the sterile fungus significantly reduced the disease incidence of bacterial angular leaf spot. Phoma and sterile fungus protected plants significantly against Fusarium wilt. Roots treated with CFs of these fungal isolates induced lignification at Colletotrichum penetration points indicating the presence of an elicitor in the CFs. The elicitor activity of CFs was evaluated by the chemiluminescence assay using tobacco callus and cucumber fruit disks. The CFs of all isolates elicited conspicuous superoxide generation. The chemiluminescence activity of the CF of Penicillium was extremely high, and its intensity was almost 100-fold higher than that of other isolates. The chemiluminescence activity was not lost following treatment with protease or autoclaving or after removal of lipid. The MW 12,000 dialyzed CF fraction was highly effective in eliciting chemiluminescence activity. Chemiluminescence emission from cucumber fruit disks treated with Penicillium was the same as that obtained from tobacco callus, except that the lipid fraction also showed a high activity. Both the MW 12,000 fraction and the lipid fraction induced lignification in the epidermal tissues of cucumber hypocotyls.     

Effects of sex and gonadal steroids on arginine vasotocin and mesotocin in the pineal gland and neurohypophysis of White Leghorn fowls

1. Pineal and neurohypophysial arginine vasotocin (AVT) and mesotocin (MT) were measured in White Leghorn hens, cockerels and castrated males treated with either testosterone propionate (TP) or oestradiol benzoate (EB) (n = 10/group). The lighting regimen was 14 h light: 10 h dark, supplied by natural diffused sunlight and incandescent bulbs. 2. Both AVT and MT were detected in the pineal gland of all the chickens. 3. There was no significant effect of either sex or treatments on pineal MT. 4. Females had about 4 times more pineal AVT than males, regardless of their treatment. There was no effect of the treatments on pineal AVT in the males. 5. No sexual difference in neurohypophysial AVT was detected, but the neurohypophysis of the castrated males treated with EB contained less AVT than the neurohypophysis of the intact males. 6. Intact males had about twice as much MT in the neurohypophysis as females. Castrated males treated with either TP or EB had similar concentrations of neurohypophysial MT, which were lower than that of the intact males, but higher than that of the females.     

Determination of bacteria constituting ruminal fibrolytic consortia developed on orchard grass hay stem

To determine the relationship between Fibrobacter succinogenes and other rumen bacteria, the bacterial community structure on fiber was analyzed by using two different materials. These were ruminally incubated orchard grass hay stems without and with preincubation with F. succinogenes (natural and artificial consortia, respectively). The natural consortium mainly consisted of Firmicutes (56.6%) and Bacteroidetes (33.1%), while the artificial consortium showed a significantly higher proportion of Firmicutes (85.5%) and a lower proportion of Bacteroidetes (4.6%). At species or genus level, Butyrivibrio fibrisolvens, the U2 group, Ruminococcus albus and Lachnospiraceae incertae sedis made up a higher proportion in the artificial consortium. The most dominant bacterial group was the Butyrivibrio‐Pseudobutyrivibrio‐Lachnospiraceae incertae sedis group, which accounted for 19.7% in the natural and 29.5% in the artificial consortium. Within the genus Butyrivibrio, the phylogenetic groups SA and VA2 and phylogeny‐undefined Butyribivrio, but not VA1, were detected at high frequency in the artificial consortium. These results suggest that ecological and possibly functional relationships exist in the rumen among F. succinogenes, a subset of B. fibrisolvens, the U2 group, R. albus and Lachnospiraceae incertae sedis.     

Effect of soybean husk supplementation on the fecal fermentation metabolites and microbiota of dogs

In vitro fermentation and in vivo feeding experiments were conducted to characterize the effects of soybean (Glycine max) husk on the fecal fermentation metabolites and microbiota of dogs. An in vitro fermentation study using feces from three Toy Poodle dogs (6.5 ± 3.5 months in age and 2.9 ± 0.4 kg in body weight) revealed that the fecal inoculum was able to ferment soybean husk (supplemented at 0.01 g/mL culture) and increased levels of short chain fatty acids (SCFA) and Bifidobacterium, irrespective of pre‐digestion of the husk by pepsin and pancreatin. In a feeding experiment, four Shiba dogs (7–48 months in age and 7.5 ± 1.7 kg in body weight) fed a commercial diet supplemented with 5.6% soybean husk showed an increase in SCFA, such as acetate and butyrate, and lactate, and a decrease in indole and skatole in the feces compared to those fed a 5.6% cellulose diet. Real‐time PCR assay showed that soybean husk supplementation stimulated the growth of lactobacilli, Clostridium cluster IV including Faecalibacterium prausnitzii, Clostridium cluster XIVa, Bacteroides‐Prevotella‐Porphyromonas group but inhibited the growth of Clostridium cluster XI. Both in vitro and in vivo experiments indicated that soybean husk supplementation improves gastrointestinal health through optimization of beneficial organic acid production and increase of beneficial bacteria. Therefore, soybean husk is suggested to be applicable as a functional fiber in the formulation of canine diets.     

Phytoplankton surveys off the southern Myanmar coast of the Andaman Sea: an emphasis on dinoflagellates including potentially harmful species

A detailed list of dinoflagellate species for the Mergui Archipelago, off southern Myanmar, was compiled for the first time. This was based on surveys conducted in two seasons in pre- and post-monsoons, and on observations for both plankton and cyst assemblages. In the plankton samples, 57 and 26 dinoflagellate species were recorded, respectively, in the pre- and post-monsoons. Among the list from plankton and cyst samples, harmful species were found: red-tide species including Prorocentrum spp. and Alexandrium affine, and causative species of paralytic shellfish poisoning, e.g., Alexandrium tamiyavanichii and Gymnodinium catenatum, and of diarrhetic shellfish poisoning, e.g., Dinophysis spp. Therefore, although no incidences have been reported yet, attention must be paid to these harmful algal bloom (HAB) events in Myanmar where exploitation of fishery resources is drastically increasing. Other dinoflagellate compositions were also unique and may relate to the oceanographic system in this region. In the pre-monsoon, rather rare oceanic species of Ornithocercus spp. were found concurrently with neritic species, probably due to the extensive southwesterly current from the Indian Ocean. Throughout the seasons, diverse species of Protoperidinium were predominately recorded in both planktonic and sediment samples, indicating richness of prey organisms probably sustained by upwelling systems.     

Physiological effects of arginine vasotocin and mesotocin in cockerels

1. The effects of continuous infusion of 0.1, 1.0 and 10.0 mU/min/kg body weight of arginine vasotocin (AVT) or mesotocin (MT) on cardiovascular and thermoregulatory responses, on plasma osmolality and ionic composition and on plasma concentrations of AVT, MT, prolactin and aldosterone, were investigated in conscious White Leghorn cockerels.

2. Neither of the peptides, at any dose, affected cardiovascular functions, plasma ions and osmolality. Infusion of MT at the rate of 10 mU/min/kg body weight increased respiratory rate. Both peptides at doses of 1 and 10 mU/min/kg reduced the temperatures of the comb and shank but had no effect on the skin and cloaca.

3. Doses of 0.1 and 1.0 mU MT/mu/kg reduced plasma aldosterone and at 10 mU/min/kg increased plasma AVT. At any given dose MT had no effect on plasma prolactin. AVT at 0.1 and 1.0 mU/min/kg of AVT reduced plasma MT. AVT at 1.0 mU/min/kg increased plasma prolactin and at 10 mU/min/kg reduced plasma aldosterone.

4. During saline infusion, plasma MT was positively correlated with plasma AVT and negatively correlated with respiratory rate and cloacal temperature. Plasma AVT showed a positive correlation with plasma MT and aldosterone and a negative correlation with respiratory rate and skin temperature.

5. During saline infusion, there was no significant correlation between cardiovascular functions, or plasma osmolality and ionic composition and plasma MT or AVT.

6. The present study suggests that interrelationships between circulating concentrations of AVT and MT do exist and that AVT affects