De novo venom gland transcriptomics of Calliophis bivirgata flaviceps: uncovering the complexity of toxins from the Malayan blue coral snake

The Malayan blue coral snake, Calliophis bivirgata flaviceps, is a medically important venomous snake in Southeast Asia. However, the complexity and diversity of its venom genes remain little explored. Methods: To address this, we applied high-throughput next-generation sequencing to profile the venom gland cDNA libraries of C. bivirgata flaviceps. The transcriptome was de novo assembled, followed by gene annotation, multiple sequence alignment and analyses of the transcripts. Results: A total of 74 non-redundant toxin-encoding genes from 16 protein families were identified, with 31 full-length toxin transcripts. Three-finger toxins (3FTx), primarily delta-neurotoxins and cardiotoxin-like/cytotoxin-like proteins, were the most diverse and abundantly expressed. The major 3FTx (Cb_FTX01 and Cb_FTX02) are highly similar to calliotoxin, a delta-neurotoxin previously reported in the venom of C. bivirgata. This study also revealed a conserved tyrosine residue at position 4 of the cardiotoxin-like/cytotoxin-like protein genes in the species. These variants, proposed as Y-type CTX-like proteins, are similar to the H-type CTX from cobras. The substitution is conservative though, preserving a less toxic form of elapid CTX-like protein, as indicated by the lack of venom cytotoxicity in previous laboratory and clinical findings. The ecological role of these toxins, however, remains unclear. The study also uncovered unique transcripts that belong to phospholipase A2 of Groups IA and IB, and snake venom metalloproteinases of PIII subclass, which show sequence variations from those of Asiatic elapids. Conclusion: The venom gland transcriptome of C. bivirgata flaviceps from Malaysia was de novo assembled and annotated. The diversity and expression profile of toxin genes provide insights into the biological and medical importance of the species.(AU)

De novo venom gland transcriptomics of Calliophis bivirgata flaviceps: uncovering the complexity of toxins from the Malayan blue coral snake

The Malayan blue coral snake, Calliophis bivirgata flaviceps, is a medically important venomous snake in Southeast Asia. However, the complexity and diversity of its venom genes remain little explored. Methods: To address this, we applied high-throughput next-generation sequencing to profile the venom gland cDNA libraries of C. bivirgata flaviceps. The transcriptome was de novo assembled, followed by gene annotation, multiple sequence alignment and analyses of the transcripts. Results: A total of 74 non-redundant toxin-encoding genes from 16 protein families were identified, with 31 full-length toxin transcripts. Three-finger toxins (3FTx), primarily delta-neurotoxins and cardiotoxin-like/cytotoxin-like proteins, were the most diverse and abundantly expressed. The major 3FTx (Cb_FTX01 and Cb_FTX02) are highly similar to calliotoxin, a delta-neurotoxin previously reported in the venom of C. bivirgata. This study also revealed a conserved tyrosine residue at position 4 of the cardiotoxin-like/cytotoxin-like protein genes in the species. These variants, proposed as Y-type CTX-like proteins, are similar to the H-type CTX from cobras. The substitution is conservative though, preserving a less toxic form of elapid CTX-like protein, as indicated by the lack of venom cytotoxicity in previous laboratory and clinical findings. The ecological role of these toxins, however, remains unclear. The study also uncovered unique transcripts that belong to phospholipase A2 of Groups IA and IB, and snake venom metalloproteinases of PIII subclass, which show sequence variations from those of Asiatic elapids. Conclusion: The venom gland transcriptome of C. bivirgata flaviceps from Malaysia was de novo assembled and annotated. The diversity and expression profile of toxin genes provide insights into the biological and medical importance of the species.(AU)

Bovine abortion associated with Staphylococcus aureus infection: characterization of S. aureus strain isolated from fetal tissues / Aborto bovino associado à infecção por Staphylococcus aureus: caracterização da cepa de S. aureus isolada a partir de tecidos fetais

Staphylococcus aureus is a gram-positive bacterium, commonly found colonizing the skin and mucous membranes of humans and animals. This report describes a case of fetal loss associated with S. aureus infection in a cow. A six-month old, crossbred male bovine fetus from a beef farm was submitted for necropsy. At gross examination fibrinous pleuropneumonia was observed. Histologically, lesions were restricted to the lungs and consisted of marked multifocal to coalescing areas of inflammatory infiltrate of neutrophils, abundant fibrin exudation, necrosis of bronchiolar epithelium and numerous aggregates of coccoid bacteria. Lung and abomasal fluid bacterial culture yielded pure culture of S. aureus, which was characterized as a multidrug resistant strain. Molecular analysis indicated that the studied strain presented several genes of virulence factors including toxic shock syndrome toxin-1 (tst), staphylococcal enterotoxin type A (sea), Panton-Valentine leukocidin (pvl), alpha-hemolysin (hla) and delta-hemolysin (hld). This report documents an infrequent case of fetal loss in cattle due to infection with a highly virulent S. aureus strain.(AU)

Staphylococcus aureus é uma bactéria gram-positiva, comumente encontrada colonizando a pele e as membranas mucosas de humanos e animais. O presente relato descreve um caso de aborto bovino associado à infecção por S. aureus. Um feto bovino, macho, cruzado, com seis meses de idade gestacional proveniente de uma fazenda de gado de corte foi submetido para a necropsia. Pleuropneumonia supurativa foi observada na avaliação macroscópica. Histologicamente as lesões encontravam-se restritas aos pulmões e eram representadas por infiltrado inflamatório acentuado, multifocal a coalescente de neutrófilos, acentuada exsudação de fibrina, necrose do epitélio bronquiolar e numerosos agregados bacterianos cocoides. A cultura bacteriana de fragmento de pulmão e líquido do abomaso revelou o crescimento puro de S. aureus, que foi caracterizado como uma cepa multirresistente a drogas. Análises moleculares indicaram que a cepa estudada apresentava vários fatores de virulência, incluindo toxina 1 da síndrome do choque tóxico (TSST-1), enterotoxina estafilocócica tipo A (sea), leucocidina Panton-Valentine (pvl), hemolisina alfa (hla) e hemolisina delta (hld). O presente relato documenta um caso infrequente de aborto bovino devido à infecção por uma cepa altamente virulenta de S. aureus.(AU)

Phytotoxicity associated to microcystins: a review / Fitotocixidade associada às microcistinas: uma revisão

Microcystins (MC) are the most studied toxins of cyanobacteria since they are widely distributed and account for several cases of human and animal poisoning, being potent inhibitors of the serine/threonine protein phosphatases 1 (PP1) and 2A (PP2A). The phosphatases PP1 and PP2A are also present in plants, which may also suffer adverse effects due to the inhibition of these enzymes. In aquatic plants, biomass reduction is usually observed after absorption of cyanotoxins, which can bioaccumulate in its tissues. In terrestrial plants, the effects caused by microcystins vary from inhibition to stimulation as the individuals develop from seedling to adult, and include reduction of protein phosphatases 1 and 2A, oxidative stress, decreased photosynthetic activity and even cell apoptosis, as well as bioaccumulation in plant tissues. Thus, the irrigation of crop plants by water contaminated with microcystins is not only an economic problem but becomes a public health issue because of the possibility of food contamination, and this route of exposure requires careful monitoring by the responsible authorities.(AU)

Microcistinas (MC) são as toxinas de cianobactérias mais estudadas, uma vez que são amplamente distribuídas e responsáveis por vários casos de intoxicação humana e animal. São potentes inibidoras das proteínas fosfatases serina/treonina 1 (PP1) e 2A (PP2A). As fosfatases PP1 e PP2A também estão presentes em plantas, as quais podem sofrer efeitos adversos devido à inibição dessas enzimas. Em plantas aquáticas, a redução da biomassa é geralmente observada após absorção de cianotoxinas que podem bioacumular em seus tecidos. Em plantas terrestres, os efeitos causados pelas microcistinas variam de inibição ao estímulo, como no desenvolvimento de plântulas ao estádio adulto, e incluem a redução de proteínas fosfatases 1 e 2A, estresse oxidativo, diminuição da atividade fotossintética e até mesmo apoptose celular, bem como a bioacumulação em tecidos de plantas. Assim, a irrigação de plantas cultivadas com água contaminada com microcistina não é apenas um problema econômico, mas torna-se um problema de saúde pública, devido à possibilidade de contaminação dos alimento, sendo uma via de exposição que requer um monitoramento cuidadoso por parte das autoridades responsáveis.(AU)

Application of statistical experimental design for optimisation of bioinsecticides production by sporeless Bacillus thuringiensis strain on cheap medium

In order to overproduce bioinsecticides production by a sporeless Bacillus thuringiensis strain, an optimal composition of a cheap medium was defined using a response surface methodology. In a first step, a Plackett-Burman design used to evaluate the effects of eight medium components on delta-endotoxin production showed that starch, soya bean and sodium chloride exhibited significant effects on bioinsecticides production. In a second step, these parameters were selected for further optimisation by central composite design. The obtained results revealed that the optimum culture medium for delta-endotoxin production consists of 30 g L-1 starch, 30 g L-1 soya bean and 9g L-1 sodium chloride. When compared to the basal production medium, an improvement in delta-endotoxin production up to 50% was noted. Moreover, relative toxin yield of sporeless Bacillus thuringiensis S22 was improved markedly by using optimised cheap medium (148.5 mg delta-endotoxins per g starch) when compared to the yield obtained in the basal medium (94.46 mg delta-endotoxins per g starch). Therefore, the use of optimised culture cheap medium appeared to be a good alternative for a low cost production of sporeless Bacillus thuringiensis bioinsecticides at industrial scale which is of great importance in practical point of view.(AU)

Produção de hemolisinas por Staphylococcus aureus isolados de casos de mastite bovina subclínica / Production of hemolysins by Staphylococcus aureus isolated from bovine subclinical mastitis

Com o objetivo de avaliar a produção das hemolisinas alfa, beta e delta, foram analisadas 78 amostras de Staphylococcus aureusisoladas de casos de mastite bovinasubclínica. Em ágar sangue de ovino e/ouequino,100% das amostras apresentaram atividade hemolítica, com 58 amostras produzindo a toxina alfa; 73 a delta e 76 a beta, correspondendo a 74,4, 93,6 e 97,4% das amostras, respectivamente. A análise da produção combinada mostrou que em 70,5% das amostras houve co-produção de alfa+beta+delta; em 20,5% beta+delta; em 2,6% alfa+beta; e em 1,3% alfa+delta. A produção de um único tipo de toxina foi observada em apenas quatro amostras, sendo três (3,8%) produtoras datoxina beta e uma (1,3%) amostra da toxina delta. A mensuração do diâmetro dos halos hemolíticos indicou produção de uma grande quantidade de toxina. Além disso, a maioria das amostras (70,5%) demonstrou atividade hemolítica às 24 horas de incubação. Estes resultados demonstraram que vacas com mastite subclínica são um importante reservatório de Staphylococcus aureuscom habilidade de produzir hemolisinas.

Alpha, beta and delta hemolysins were evaluated in 78 samples of Staphylococcus aureusisolated from bovine subclinical mastitis. On sheep and/or horse blood agar,100% of the isolates produced hemolytic activity and 58 were positive for alfa-toxin; 73 for delta-toxin and 76 for beta-toxin, which accounted for 74.4, 93.6 and 97.4% of the isolates, respectively. The production of alpha+beta+deltatoxins was observed in 70.5% of the isolates; beta+deltain 20.5%; alpha+betain 2.6%; and alpha+deltain 1.3%. Four isolates produced one toxin type alone with three (3.8%) of them producing beta-toxin and one (1.3%) delta-toxin. The measurementof the hemolytic area showed a high amount of toxin production. Also, the majority of isolates (70.5%) produced hemolysis at 24 hours after incubation. Theseresultsdemonstrated thatcows with a subclinical mastitis are an important reservoir of hemolytic Staphylococcus aureus.

Standardization of the PCR technique for the detection of delta toxin in Staphylococcus spp.

Coagulase-negative staphylococci (CNS), components of the normal flora of neonates, have emerged as important opportunistic pathogens of nosocomial infections that occur in neonatal intensive care units. Some authors have reported the ability of some CNS strains, particularly Staphylococcus epidermidis, to produce a toxin similar to S. aureus delta toxin. This toxin is an exoprotein that has a detergent action on the membranes of various cell types resulting in rapid cell lysis. The objectives of the present study were to standardize the Polymerase Chain Reaction (PCR) technique for the detection of the gene responsible for the production of delta toxin (hld gene) in staphylococcal species isolated from catheters and blood cultures obtained from neonates, and to compare the results to those obtained with the phenotypic synergistic hemolysis method. Detection of delta toxin by the phenotypic and genotypic method yielded similar results for the S. aureus isolates. However, in S. epidermidis, a higher positivity was observed for PCR (97.4%) compared to the synergistic hemolysis method (86.8%). Among CNS, S. epidermidis was the most frequent isolate and was a delta toxin producer. Staphylococcus simulans and S. warneri tested positive by the phenotypic method, but their positivity was not confirmed by PCR for the hld gene detection. These results indicate that different genes might be responsible for the production of this toxin in different CNS species, requiring highly specific primers for their detection. PCR was found to be a rapid and reliable method for the detection of the hld gene in S. aureus and S. epidermidis.

Neuromuscular activity of Bothrops neuwiedi pauloensis snake venom in mouse nerve-muscle preparations

The pharmacological effects of Bothrops neuwiedi pauloensis venom on mouse phrenic nerve-diaphragm (PND) preparations were studied. Venom (20 mug/ml) irreversibly inhibited indirectly evoked twitches in PND preparations (60 ± 10 percent inhibition, mean ± SEM; p<0.05; n=6). At 50 mug/ml, the venom blocked indirectly and directly (curarized preparations) evoked twitches in mouse hemidiaphragms. In the absence of Ca2+, venom (50 mug/ml), produced partial blockade only after an 80 min incubation, which reached 40.3 ± 7.8 percent (p<0.05; n=3) after 120 min. Venom (20 mug/ml) increased (25 ± 2 percent, p< 0.05) the frequency of giant miniature end-plate potentials in 9 of 10 end-plates after 30 min and the number of miniature end-plate potentials which was maximum (562 ± 3 percent, p<0.05) after 120 min. During the same period, the resting membrane potential decreased from - 81 ± 1.4 mV to - 41.3 ± 3.6 mV 24 fibers; p<0.01; n=4) in the end-plate region and from - 77.4 ± 1.4 to -44.6 ± 3.9 mV (24 fibers; p<0.01; n=4) in regions distant from the end-plate. These results indicate that B. n. pauloensis venom acts primarily at presynaptic sites. They also suggest that enzymatic activity may be involved in this pharmacological action.(AU)

Use of endophytic diazotrophic bacteria as a vector to express the cry3A gene from Bacillus thuringiensis

The goal of this study was to evaluate the potential of endophytic diazotrophic bacteria as a vector to express a cry gene from Bacillus thuringiensis, envisaging the control of pests that attack sugarcane plants. The endophytic nitrogen-fixing bacteria Gluconacetobacter diazotrophicus strain BR11281 and Herbaspirillum seropedicae strain BR11335 were used as models. The cry3A gene was transferred by conjugation using a suicide plasmid and the recombinant strains were selected by their ability to fix nitrogen in semi-solid N-free medium. The presence of the cry gene was detected by Southern-blot using an internal fragment of 1.0 kb as a probe. The production of delta-endotoxin by the recombinant H. seropedicae strain was detected by dot blot while for G. diazotrophicus the Western-blot technique was used. In both cases, a specific antibody raised against the B. thuringiensis toxin was applied. The delta-endotoxin production showed by the G. diazotrophicus recombinant strain was dependent on the nitrogen fixing conditions since the cry3A gene was fused to a nif promoter. In the case of H. seropedicae the delta-endotoxin expression was not affected by the promoter (rhi) used. These results suggest that endophytic diazotrophic bacteria can be used as vectors to express entomopathogenic genes envisaging control of sugarcane pests.

Este estudo teve como objetivo avaliar o potencial de uso de bactérias diazotróficas endofíticas como vetores para a expressão de genes cry de Bacillus thuringiensis. As bactérias diazotróficas endofíticas Gluconacetobacter diazotrophicus estirpe BR11281 e Herbaspirillum seropedicae estirpe BR11335 foram usadas como modelo. O gene cry3A foi transferido através de um plasmídeo suicída por conjugação e os recombinantes foram selecionados pela sua capacidade de fixar nitrogênio em meio semi-sólido sem N. A presença do gene cry3A no genoma dos transconjugantes foi detectada através da técnica de "Southern blot" utilizando como sonda um fragmento de 1,0 kb, interno ao gene cry3A. A produção de delta-endotoxina pelos transconjugantes foi detectada por "Dot blot" em de H. seropedicae e por "Western blot" em G. diazotrophicus, usando-se o anticorpo específico para a toxina de B. thuringiensis. A avaliação da produção da delta-endotoxina mostrou que a expressão do gene cry3A em G. diazotrophicus é dependente do processo de fixação de nitrogênio por estar fusionado a um promotor nif nesta bactéria. No caso de H. seropedicae a expressão não foi influenciada pelo promotor de rizosfera (rhi) usado. Os resultados obtidos sugerem que estas bactérias diazotróficas endofíticas podem ser usadas como vetores para expressar genes com atividade entomopatogênica, visando o controle de pragas de cana-de-açúcar ou outras plantas de interesse econômico.