Advances on the mechanisms regulating the formation of the biofilm of Listeria monocytogenes / 生物工程学报

Listeria monocytogenes is an important food-borne pathogen. The distribution and survival of L. monocytogenes are related to its ability to form biofilms. Biofilms are resistant to adverse environments, and bacteria separated from the biofilms may lead to persistent food contaminations. The formation, maturation and structure of biofilms depend on a variety of external and internal factors, among which a variety of regulatory mechanisms play important roles. This review summarizes the regulatory mechanisms (including intracellular, intercellular and interspecific interactions) involved in the biofilm formation of L. monocytogenes in order to control the biofilm formation in food processing environments, thus providing new intervention strategy for food safety.

Sobre a relação humano-cão / Concerning the human-dog relationship / La relation homme-chien / Sobre la relación humano-perro

Resumo Neste artigo são discutidos aspectos concernentes ao início do convívio entre cães e humanos e às diferenças culturais que afetam as relações entre as duas espécies. O estudo das interações entre humanos e cães precisa trazer à tona a pluralidade de fenômenos interconectados: o processo de domesticação iniciado há milhares de anos, os efeitos evolutivos da relação entre as duas espécies e os aspectos culturais que influenciam a convivência entre nós. Considerando essa visão holística, enxergamos de maneira ampla o cenário interacionista, estabelecendo paralelos muitas vezes ignorados por estudos pontuais e/ou enviesados por paradigmas experimentais de baixa relevância ecológica para os animais.

Abstract This article discusses the beginning of the relationship between dogs and humans and the cultural differences that affect the relationships between the two species. The study of interactions between humans and dogs needs to bring to light its plurality of interconnected phenomena: the domestication process that began thousands of years ago, the evolutionary effects of their relationship and the cultural aspects that influence such coexistence. Given this holistic view, we perceive this interaction scenario broadly, establishing parallels often ignored by one-off studies and/or biased by experimental paradigms of low ecological relevance to animals.

Résumé Dans cet article sont discutés des aspects liés au début de la cohabitation entre les chiens et les humains et les différences culturelles qui affectent ces relations interspécifiques. L'étude des interactions entre humains et chiens doit faire apparaître la pluralité des phénomènes reliés entre eux : le processus de domestication qui a commencé il y a milliers d'années, les effets évolutifs de cette relation et les aspects culturels qui influencent la coexistence entre nous. Compte tenu de cette vision holistique, c'est possible de voir largement le scénario interactionniste, et d'établir des parallèles souvent ignorés par les études individuelles ou biaisé par des paradigmes expérimentaux d'importance écologique négligeable pour les animaux.

Resumen Este artículo analiza los aspectos relacionados con el comienzo de la relación entre perros y humanos, y las diferencias culturales que afectan las relaciones entre las dos especies. El estudio de las interacciones entre humanos y perros necesita sacar a la luz la pluralidad de fenómenos interconectados: el proceso de domesticación que comenzó hace miles de años, los efectos evolutivos de la relación entre las dos especies y los aspectos culturales que influyen en la convivencia entre nosotros. Teniendo en cuenta esta visión holística, vemos el panorama interaccionista de manera general, estableciendo paralelos a menudo ignorados por estudios específicos y/o sesgados por paradigmas experimentales de baja relevancia ecológica para los animales.

In vitro development and chimeric efficiency of mouse-porcine interspecies chimeric embryos in different culture systems / 生物工程学报

With the advancements of stem cells and regenerative medicine, interspecies chimera has become a hot topic and will pave a new way of providing donor sources in organ transplantation. However, the interspecies chimera is confronted with a number of scientific questions and technical obstacles, including selections of appropriate embryonic stage and appropriate culture medium; those factors will deeply influence the developmental balance between donor cells and receptor embryos. Due to its relatively rapid reproductive cycle and similar organ size to human's, porcine is a very potential donor candidate to study these questions. To compare the development and chimeric efficiency of interspecies embryos, we tested and evaluated three different culture systems, PZM-3 (Porcine zygotic medium), culture medium for iPSCs (N2B27) and 3.5 h of N2B27 before PZM-3 (N2B27(3.5 h)), and two different embryonic stages, 8-cell and blastocyst in mouse-porcine chimeric embryos using parthenogenetically activated porcine embryos and mouse induced pluripotent stem cells (miPS). The results showed that, PZM-3 was beneficial for both development of chimeric embryos and miPSCs proliferation in porcine embryos in the 8-cell injection group. After early blastocyst injection, the chimeric efficiency did not appear significantly different among the three culture systems but was lower than 8-cell injection. In summary, the results suggest that 8-cell injection and PZM-3 culture medium are more beneficial to the in vitro development and chimeric efficiency of mouse-porcine chimeric embryos.

Influenza A virus infection of healthy piglets in an abattoir in Brazil: animal-human interface and risk for interspecies transmission

Asymptomatic influenza virus infections in pigs are frequent and the lack of measures for controlling viral spread facilitates the circulation of different virus strains between pigs. The goal of this study was to demonstrate the circulation of influenza A virus strains among asymptomatic piglets in an abattoir in Brazil and discuss the potential public health impacts. Tracheal samples (n = 330) were collected from asymptomatic animals by a veterinarian that also performed visual lung tissue examinations. No slaughtered animals presented with any noticeable macroscopic signs of influenza infection following examination of lung tissues. Samples were then analysed by reverse transcription-polymerase chain reaction that resulted in the identification of 30 (9%) influenza A positive samples. The presence of asymptomatic pig infections suggested that these animals could facilitate virus dissemination and act as a source of infection for the herd, thereby enabling the emergence of influenza outbreaks associated with significant economic losses. Furthermore, the continuous exposure of the farm and abattoir workers to the virus increases the risk for interspecies transmission. Monitoring measures of swine influenza virus infections and vaccination and monitoring of employees for influenza infection should also be considered. In addition regulatory agencies should consider the public health ramifications regarding the potential zoonotic viral transmission between humans and pigs.

Quorum Sensing and Interspecies Interactions in Stenotrophomonas maltophilia.

Stenotrophomonas maltophilia is a gram-negative bacterium that is widespread in the environment and that has become important in the last years as an emerging opportunistic pathogen. Quorum sensing (QS) is a bacterial cell–cell communication process that involves the production, detection, and response to extracellular signalling molecules called autoinducers. S. maltophilia has a diffusible signal factor (DSF) that controls cell–cell communication and many functions such as motility, extracellular protease production and microcolonies formation in artificial sputum medium. This DSF signalling mediates also interspecies interactions between S. maltophilia and Pseudomonas aeruginosa such as susceptibility to polymixin and its influence on biofilm formation. The traditional approach for the treatment of infectious diseases is to kill or inhibit the growth of bacteria using antibiotics. In response to the rise in antibiotic resistance, the development and use of QS inhibition based drugs to attenuate bacterial pathogenicity is now highly required in the microbiological and clinical fields.

Formation of aerobic granular sludge under adverse conditions: Low DO and high ammonia.

In this study, two adverse environments: low dissolved oxygen (DO) and high ammonia concentration, were employed to investigate the morphology, interspecies quorum sensing, extracellular polymers (EPS) characterization and microbial communities in the formation of aerobic granular sludge. Results showed that low DO could promote filamentous bacterial outgrowth. Under high ammonia concentration aerobic granular sludge (AGS) could still be cultivated, although it was looser and lighter than the control group. During the early stage of the AGS cultivation process, AI-2 activity reached a peak value in all three reactors, and ultrasonic pre-treatment was not beneficial to the release of AI-2. During AGS formation, the production of polysaccharide exhibited increases from 12.2 % to 40.3 %, 49.6 %, and 29.3 %. And PS in R2 was the highest as the result of sludge bulking. PS/PN was 1.5~8 in the three reactors. Three-dimensional EEM fuorescence spectroscopy variation indicated the change of protein in EPS, and the highest intensity of Peak T1 was obtained. The location shift of Peak T1 was not obvious, and Peaks A, C, and T2 shifted toward longer wavelengths (red shift) of 5~60 nm, or shorter wavelengths (blue shift) of 10~25 nm on the emission scale and / or excitation scale in all three reactors. This provided spectral information on the chemical structure changes. Bacteria in R3 had the highest species diversity, and all bacteria in b-Proteobacteria were identified as genus Thauera, which suggested that simultaneous nitrification and denitrification occurred in R3. The filamentous bacteria in seed sludge and R2 were species-richer. There was a low abundance of filamentous bacteria in R1 and R3, which contributed to the granule structure stability.

Expression patterns of influenza virus receptors in the respiratory tracts of four species of poultry

The primary determinant of influenza virus infectivity is the type of linkage between sialic acid and oligosaccharides on the host cells. Hemagglutinin of avian influenza viruses preferentially binds to sialic acids linked to galactose by an alpha-2,3 linkage whereas hemagglutinin of human influenza viruses binds to sialic acids with an alpha-2,6 linkage. The distribution patterns of influenza receptors in the avian respiratory tracts are of particular interest because these are important for initial viral attachment, replication, and transmission to other species. In this study, we examined the distribution patterns of influenza receptors in the respiratory tract of chickens, ducks, pheasants, and quails because these species have been known to act as intermediate hosts in interspecies transmission. Lectin histochemistry was performed to detect receptor-bearing cells. Cell-specific distribution of the receptors was determined and expression densities were compared. We observed species-, site-, and cell-specific variations in receptor expression. In general, receptor expression was the highest in quails and lowest in ducks. Pheasants and quails had abundant expression of both types of receptors throughout the respiratory tract. These results indicate that pheasants and quails may play important roles as intermediate hosts for the generation of influenza viruses with pandemic potential.

Strain diversity within Mycobacterium avium subspecies paratuberculosis — A review.

Mycobacterium avium subspecies paratuberculosis (MAP), is the etiological agent of Johne’s disease (or paratuberculosis) in animals and has also been linked with Crohn’s disease of human beings. Extreme fastidious nature of the organism (MAP) has hampered studies on diversity within the organism. Studies based on phenotypic properties like growth rate, pigmentation, lipid profile etc., are unable to provide complete information on diversity of MAP organism in nature. However, with the advent of molecular assays (IS900 RFLP, PFGE, IS1311 PCR-REA, SSR typing, VNTR typing etc.) in last 2 decades, progress has been made to differentiate MAP strains. MAP isolates have been classified into various types and subtypes using these molecular tools. Optimization of these typing assays has led to generation of new information about MAP strains, subtypes, their comparative genomics, relative evolution, comparative virulence etc. Knowledge of strain diversity is important for better understanding of molecular and sero-epidemiology, infection and patho-biology, vaccine development and planning control strategies. The present review provides available information on MAP strains, host adaptations, their virulence, comparative genomics, relative genetic evolution and differentiation.

In vitro comparison of thienorphine metabolism in liver microsomes of human,Beagle dog and rat / 药学学报

The inter-species differences of thienorphine metabolism were investigated in human, Beagle dog and rat liver microsomes, by comparing enzyme kinetics of the parent drug and the formation of its major metabolites. The incubation systems of thienorphine with liver microsomes of the three species were optimized in terms of thienorphine concentration, microsomal protein content and incubation time. The concentrations of thienorphine and its metabolites in incubates were measured by a LC-MS/MS method. The biotransformation of thienorphine by human liver microsomes was the lowest among the three species. The Km, Vmax, CLint and T1/2 of thienorphine obtained from human liver microsomes were (4.00 ? 0.59) ?mol?L-1, (0.21 ? 0.06) ?mol?L-1?min-1, (117 ? 3.19) mL?min-1?kg-1 and (223 ? 6.10) min, respectively. The corresponding kinetic parameters for dog and rat liver microsomes were (3.57 ? 0.69) and (3.28 ? 0.50) ?mol?L-1, (0.18 ? 0.04) and (0.14 ? 0.04) ?mol?L-1?min-1, (213 ? 1.06) and (527 ? 7.79) mL?min-1?kg-1, (244 ? 1.21) and (70.7 ? 1.05) min, respectively. A total of six phase I metabolites were observed in liver microsomes, including one N-dealkylated metabolite, three oxidative metabolites and two N-dealkylated oxidation metabolites. All these six metabolites were detected in the liver microsomes of the three species. However, the relative amounts of the metabolites generated were different in three species. The results indicated that the major phase I metabolic pathway of thienorphine was similar in the liver microsomes from all three species. However, the inter-species differencesobserved were relative amounts of the metabolites as well as the metabolic characteristics of thienorphine in liver microsomal incubates.

Production of cloned sei whale (Balaenoptera borealis) embryos by interspecies somatic cell nuclear transfer using enucleated pig oocytes

In this study, we examined the feasibility of using subzonal cell injection with electrofusion for interspecies somatic cell nuclear transfer (iSCNT) to produce sei whale embryos and to improve their developmental capacity by investigating the effect of osmolarity and macromolecules in the culture medium on the in vitro developmental capacity. Hybrid embryos produced by the electrofusion of fetal whale fibroblasts with enucleated porcine oocytes were cultured in modified porcine zygote medium-3 to examine the effects of osmolarity and fetal serum on their in vitro developmental capacity. More than 66% of the whale somatic cells successfully fused with the porcine oocytes following electrofusion. A portion (60~81%) of the iSCNT whale embryos developed to the two- to four-cell stages, but no embryos were able to reach the blastocyst stage. This developmental arrest was not overcome by increasing the osmolarity of the medium to 360 mOsm or by the addition of fetal bovine or fetal whale serum. Our results demonstrate that sei whale-porcine hybrid embryos may be produced by SCNT using subzonal injection and electrofusion. The pig oocytes partly supported the remodeling and reprogramming of the sei whale somatic cell nuclei, but they were unable to support the development of iSCNT whale embryos to the blastocyst stage.

Competição entre larvas de Aedes aegypti e Aedes albopictus em laboratório / Competition between Aedes aegypti and Aedes albopictus larvae in the laboratory

Este estudo teve como objetivo avaliar os efeitos da competição larval intra e interespecífica entre Aedes aegypti e Aedes albopictus, sobre sobrevivência de larvas, tempo de desenvolvimento e comprimento de asa. O experimento foi realizado em três densidades com 5 proporções das espécies. A sobrevivência de Aedes aegypti apresentou-se superior a de Aedes albopictus em densidade intermediária e inferior em densidade alta. Somente Aedes albopictus teve seu tempo de desenvolvimento afetado. Diferenças encontradas nas comparações das combinações das espécies demonstraram que o comprimento médio de asas de Aedes aegypti, no geral, foi maior que Aedes albopictus. Nas duas espécies, a competição afetou mais o comprimento de asa e a sobrevivência que o tempo de desenvolvimento. Aedes aegypti parece apresentar maior capacidade competitiva em relação a Aedes albopictus em densidade intermediária.

This study had the aim of evaluating the effects of intra and interspecies larval competition between Aedes aegypti and Aedes albopictus, survival of larvae time taken to develop and wing length. The experiment was carried out with three densities and five proportions of the species. Aedes aegypti survival was greater than Aedes albopictus survival at intermediate density, while it was lower at high density. Only the time taken for Aedes albopictus to develop was affected. The differences found in comparing the species combinations demonstrated that the mean wing length of Aedes aegypti was generally greater than that of Aedes albopictus. For both species, competition had greater effect on wing length and survival than on the time taken to develop. Aedes aegypti seems to present better competitive capacity than does Aedes albopictus, at intermediate density.

Investigation of Chigger Mites on the Rat Eothenomys miletus in Yunnan / 中国寄生虫学与寄生虫病杂志

Objective To understand the species,species distribution,the dominant species and their interspecies interaction of chigger mites on Eothenomys miletus(a dominant species of rats)in Yunnan.Method The rats were captured with mouse traps in 16 counties(or cities)during 2000-2004.All mites on the surface of two auricles of the hosts were collected and identified.The patch index(m*/m)and the coefficient of association(V)were adopted to judge the spatial distribution patterns and interspecies interaction of the dominant chigger mite species among different individuals of the rats(E.miletus).Results 1157 individuals of E.miletus were captured from 16 counties(citys).37613 chigger mites(belonging to 3 subfamily,9 genus and 80 species)were collected from the auricles(body surface)of 1157 rat hosts with a high “overall mite infestation rate”(68.2%)and “overall mite index”(32.5).Six species of mites were found dominant on E.miletus:Leptotrombidium scutellare,Leptotrombidium sinicum,Helenicula simena,Leptotrombidium eothenomydis,Herpetacarus hastoclavus and Leptotrombidium hiemalis.The distribution of the chigger mites among different individuals of E.miletus showed an aggregation pattern.Both positive and negative association existed between each two dominant species of chigger mites.Conclusion The species composition of chigger mites on Eothenomys miletus is complex with abundant individuals,which reflects a high species diversity of the mites.The main species of chigger mites tend to an aggregation on the body surface of E.miletus.

Advance in Research into the Infection of Avian Influenza Virus in Humans Crossing the Species Barrier / 微生物学通报

avian influenza virus (AIV) can not only infect avian and cause pandemics,but also result infection and initiate pandemics in humans and other mammal animals,crossing the species barrier.There have been some advance in research into the nonspecific species barrier of human respiratory tract against AIV infection and the mechanism of the infection of AIV in humans in recent years.