Recent update on the prevalence of Vibrio species among cultured grouper in Peninsular Malaysia

Vibrio infections are common among marine fish and lead to serious problems in the aquaculture sector. This study reports a recent occurrence of Vibrio species (spp.) isolated from cultured groupers in Peninsular Malaysia using the gyrB and pyrH genes. A total of 147 Vibrio strains were successfully isolated from 77 (64%) groupers using culture method and subjected to gyrB and pyrH sequencing for species identification and confirmation. Results showed that 89% of Vibrio strains were identified and clustered to six groups of Vibrio spp., while 11% were not clustered to any Vibrio spp. using the gyrB sequences. Meanwhile, by analysis of the pyrH sequences all the 147 Vibrio strains (100%) were successfully identified and clustered into 11 groups of Vibrio spp., including the gyrB non‐identified strains. The pyrH gene provides a better resolution for identification of Vibrio spp. compared with the gyrB gene. Thus, the pyrH gene was more suitable for a rapid determination of Vibrio spp. distribution in Peninsular Malaysia. Using the pyrH gene, our study found higher prevalence of Vibrio vulnificus (33%), V. alginolyticus (24%) and V. parahaemolyticus (22%), followed by V. rotiferianus (5%), V. harveyi (3%), V. tubiashii (2%), V. campbellii (2%), V. ponticus (1%), V. diabolicus (1%), V. owensii (1%) and others Vibrio sp. (7%). Thus, the results of this study revealed that the occurrence of pathogenic vibrios among grouper fish is still high in Malaysian aquaculture. In addition, the pyrH gene was proved as a suitable marker for rapid identification of Vibrio species compared with the gyrB gene.     

Soil urease activity and kinetics

The activity and kinetic properties of urease in several Malaysian soils were examined. The values for K_m and V_max of the soils computed according to the Hanes equation were in general agreement with other reports as far as magnitudes were concerned. A significant correlation between K_m and V_max was also obtained. The urease activity of the soils was variable, and it was noted that expression of the activity as the time required to hydrolyze half of the applied urea has limited use in soils of low activity. In all soils studied, inhibition of urease activity was effectively achieved using Ag⁺, while Cu²⁺ was only effective in two soils, and marginally effective in the other two soils. Urease inhibitors have potential applications in reducing volatilization losses of ammonia derived from urea applied to soils.     

Studies on plant regeneration and somaclonal variation in Saintpaulia ionantha Wendl. (African violet)

Efficient plant regeneration of Saintpaulia ionantha (African violet) has been obtained in the present study. MS medium supplemented with 1.0 mg L(-1) IAA and 2.0 mg L(-1) Zeatin resulted in 100% shoot regeneration and induced the highest number of shoots (average 15.0 +/- 0.8 shoots per explant) after being cultured for 8 weeks. The above hormone combination was optimum for shoot regeneration. Most of Saintpaulia ionantha plantlets derived from tissue culture system could be hardened and transferred to the greenhouse conditions with 84.0 +/- 1.6% success rate. However, regenerated plantlets of Saintpaulia ionantha (even after 12-months-old) failed to flower. Morphological characters of regenerated plantlets of Saintpaulia ionantha were observed and compared with in vivo (intact) plants. Regenerated plantlets showed some differences in morphological characters, such as height and leaf size, texture and colour, but the plantlets showed no variation in leaf arrangement and leaf margin. However, the morphological characters of the regenerated plantlets were found to be unstable.     

Effects of different organic additives on in vitro shoot regeneration of Celosia sp

Nowadays, many researches were conducted in minimizing tissue culture technology due to the overhead of cost needed. The purpose of this study was to investigate the effects of using five kinds of organic additives at four level concentrations responsive to the number of shoots produced for eight weeks in culture. Stem segment explants of Celosia sp. were cultured on MS medium that have been supplemented with different kinds of extract juice that serve as organic additives which are mature coconut, young coconut, papaya, banana and tomato at 20, 30, 50 and 70 ml L-1. The numbers of shoot on each explant were recorded and the mean of ten replicates explants were calculated. Among the media used, young coconut water at 70 ml L1- induced the highest shoot regeneration (14.21+/-8.26), followed by mature coconut water at 50 ml L-1 (13.14+/-10.33). Banana and tomato juice promote highest shoot regeneration of stem segments at 50 ml L-1 that produced 9.57+/-4.68 and 9.28+/-5.82 shoots per explants, respectively. While the lowest concentration which at 20 ml L-1 of papaya juice showed highest shoot regeneration (10.50+/-3.45) produced among the three other concentration tested. Statistical results showed that there were significant differences interactions effects (p<0.05) in terms of number of shoot regenerated between the types of extracts juices determined by ANOVA test. Comparing number of shoots regenerated that were cultured in control media, it showed higher than all of experimental medium composition. There were no big different in cost required in preparation of control media and the experimental media. Applications of five kinds of local fruit in tissue culture media should be considered since it responsive in shoot regeneration.     

A Burkholderia pseudomallei toxin inhibits helicase activity of translation factor eIF4A

The structure of BPSL1549, a protein of unknown function from Burkholderia pseudomallei, reveals a similarity to Escherichia coli cytotoxic necrotizing factor 1. We found that BPSL1549 acted as a potent cytotoxin against eukaryotic cells and was lethal when administered to mice. Expression levels of bpsl1549 correlate with conditions expected to promote or suppress pathogenicity. BPSL1549 promotes deamidation of glutamine-339 of the translation initiation factor eIF4A, abolishing its helicase activity and inhibiting translation. We propose to name BPSL1549 Burkholderia lethal factor 1.     

Effectiveness of single and combined use of selected dietary probiotic and prebiotics on growth and intestinal conditions of striped catfish (Pangasianodon hypophthalmus,Sauvage, 1978) juvenile

Aquaculture International - Single or combined effect of yeast, galactooligosaccharide (GOS), mannanoligosaccharide (MOS), and β-glucan was evaluated on the growth performance, nutrient...     

Effect of Lactobacillus acidophilussupplementation on growth performances,digestive enzyme activities and gut histomorphology of striped catfish (Pangasianodon hypophthalmusSauvage, 1878) juveniles

The influence of dietary supplementation of Lactobacillus acidophilus, on growth performance, digestive enzyme activities, gut histomorphology and gut microflora were evaluated in juveniles striped catfish (Pangasianodon hypophthalmus). Five experimental diets were formulated by supplementing 0, 10³, 10⁵, 10⁷ and 10⁹ CFU/g L. acidophilus in fishmeal and casein‐based semi‐purified diet. Triplicate groups of striped catfish (21.69 ± 0.18 g) were stocked in 15 fiberglass tanks with stocking density of 25 individuals per tank and fed twice daily at 2.5% of the fish body weight for 12 weeks. Weight gain, specific growth rate, feed conversion ratio and the protein efficiency ratio were significantly higher in fish fed with 10⁵ and 10⁷CFU/g L. acidophilussupplemented diets compared with the other treatment groups. Compared with the control and fish fed low (10³ CFU/g) L. acidophilus supplementation, those fed with 10⁵ and 10⁷ CFU/g had significantly higher (p < 0.05) apparent protein digestibility. Inclusion of L. acidophilus at 10⁷ CFU/g diet significantly increased amylase, protease and lipase activities. Microscopic analysis showed that the villi length in both the anterior and posterior gut and microvilli length in the posterior gut increased significantly in fish fed L. acidophilus supplementation at 10⁵ and 10⁷ CFU/g of diet. The fish fed L. acidophilus supplemented diets significantly increased the total lactic acid bacteria counts in the gut of striped catfish compared with the control‐fed group. Based on gut histomorphology and growth performance, inclusion of L. acidophilus at 10⁵ CFU/g appears to have the most positive effect on striped catfish farming.     

1973—2017年藏北高寒牧区主要气象要素变化特征分析

为分析全球气候变化下藏北高原主要气象要素的变化特征,采用趋势分析、小波分析、突变点分析等研究方法,利用逐月站点气象数据,分析了1973—2017年藏北高原地区的主要气象要素的多尺度时间变化特征。结果表明：在全球气候变化下藏北高寒牧区的各主要气象要素变化显著,其中气温以0.45℃/10 a速率显著的升高,风速以-0.27 m/(s·10 a)速率呈极显著减小趋势,降水以6.48 mm/10 a速率呈不显著增加趋势;从季节变化来看,春季较为特殊,表现为增温缓慢、风速减幅最大、降水增加最为显著等特点,其他季节在各要素上变化较为均匀;周期变化上在去除显著的全球变暖的线性趋势后气温和降水都存在显著的准3年周期变化,且在发生时域上有互补特征。