Impacts of type II toxin-antitoxin systems on cell physiology and environmental behavior in acetic acid bacteria.

Acetic acid bacteria (AAB) are a group of Gram-negative and strictly aerobic microorganisms widely used in vinegar industry, especially the species belonging to the genera Acetobacter and Komagataeibacter. The environments inhabited by AAB during the vinegar fermentation, in particular those natural traditional bioprocesses, are complex and dynamically changed, usually accompanied by diverse microorganisms, bacteriophages, and the increasing acetic acid concentration. For this reason, how AAB survive to such harsh niches has always been an interesting research field. Previous omic analyses (e.g., genomics, proteomics, and transcriptomics) have provided abundant clues for the metabolic pathways and bioprocesses indispensable for the acid stress adaptation of AAB. Nevertheless, it is far from fully understanding what factors regulate these modular mechanisms overtly and covertly upon shifting environments. Bacterial toxin-antitoxin systems (TAS), usually consisting of a pair of genes encoding a stable toxin and an unstable antitoxin that is capable of counteracting the toxin, have been uncovered to have a variety of biological functions. Recent studies focusing on the role of TAS in Acetobacter pasteurianus suggest that TAS contribute substantially to the acid stress resistance. In this mini review, we discuss the biological functions of type II TAS in the context of AAB with regard to the acid stress resistance, persister formation and resuscitation, genome stability, and phage immunity. KEY POINTS: • Type II TAS act as regulators in the acid stress resistance of AAB. • Type II TAS are implicated in the formation of acid-tolerant persister cells in AAB. • Type II TAS are potential factors responsible for phage immunity and genome stability.

Effectiveness and mechanism of aluminum/iron co-modified calcite capping and amendment for controlling phosphorus release from sediments.

The effectiveness and mechanism of aluminum/iron co-modified calcite (Al/Fe-CA) for the control of phosphorus (P) liberation from sediments was investigated. The results showed that Al/Fe-CA possessed good sorption performance for phosphate, and the maximum phosphate sorption capacity for Al/Fe-CA could reach 27.0 mg/g. The major mechanisms involved the surface adsorption of phosphate on calcite, the precipitation between phosphate and Ca2+ leached from calcite, and the ligand exchange between Al/Fe-bound hydroxyl groups and phosphate to form the Al-O-P and Fe-O-P inner-sphere complexes. The re-releasing risk of Al/Fe-CA-bound P under the circumstances of normal pH (5-9) and reducing environment was very low. Al/Fe-CA addition could significantly reduce the risk of P releasing from sediment to overlying water (OL-water), and the inactivation of mobile P, reactive soluble P (SRP) and diffusive gradient in thin-films (DGT)-labile P in sediment by Al/Fe-CA had a great part in the suppression of sediment-P liberation to OL-water by the Al/Fe-CA amendment. Al/Fe-CA capping and fabric-wrapped Al/Fe-CA capping both could greatly reduce the risk of P releasing from sediment into OL-water, and the formation of a static layer with low concentrations of SRP and DGT-labile P in the upper sediment was the key to sustaining a high P controlling efficiency. When the applied mode of Al/Fe-CA varied from capping to amendment, although the inactivation efficiency of DGT-labile P in the overlying water and upper sediment by Al/Fe-CA would decrease to a certain degree, the inactivation efficiency of DGT-labile P in the lower sediment by Al/Fe-CA would increase. Results of this study suggest that Al/Fe-CA has the high potential to be used as an active capping or amendment material for the management of internal P loading in surface water bodies.

A biomechanical comparison of Kirschner-wire fixation on fracture stability in Salter-Harris type I fractures of the proximal humeral physis in a porcine cadaveric model.

BACKGROUND: The physis is the weakest component of immature long bones, and physeal fractures constitute about 30% of fractures in growing dogs. Fractures of the proximal humeral physis typically have a Salter Harris type I or II configuration. These fractures require accurate reduction and adequate stabilization to allow for any potential continued longitudinal bone growth, in conjunction with physeal fracture healing. Conventional internal fixation of these fractures involves insertion of two parallel Kirschner wires, although other methods described include tension band wiring, Rush pinning, and lag screws. However these recommendations are based on anecdotal evidence, and information about the biomechanical stability of physeal fracture repair is sparse. The unique anatomical structure of the epiphyseal-metaphyseal complex makes the gripping of the epiphysis for ex vivo biomechanical testing of physeal fracture repair very challenging. The objective of our study was to biomechanically assess the optimal number (three, two or one) of implanted Kirschner wires in a porcine Salter Harris I proximal humeral physeal fracture model, using motion analysis tracking of peri-fragmental retro-reflective markers while constructs were subjected to a constant axial compression and a sinusoidal torque of +/- 2 Nm at 0.5 Hz for 250 cycles. RESULTS: There were significant differences between the three constructs (three, two or one Kirschner wire repair) for gross angular displacement (p < 0.001). The difference between three pins and two pins on toggle was not significant (p = 0.053), but both three-pin and two-pin fixation significantly reduced rotational toggle compared to one-pin fixation. Construct stiffness was not significantly different between any of the pin groups (p > 0.33). CONCLUSIONS: Motion analysis tracking using peri-fragmental markers in this porcine model of physeal fracture repair found that the stability at the fracture site of one-pin fixation was significantly less than two-pin and three-pin fixation. Whether there was increased stabilization of these fractures with three-pin fixation compared to two-pin fixation was not conclusive in this porcine model.

Human infective potential of Cryptosporidium spp., Giardia duodenalis and Enterocytozoon bieneusi in urban wastewater treatment plant effluents.

Cryptosporidiosis, giardiasis, and microsporidiosis are important waterborne diseases. In the standard for wastewater treatment plant (WWTP) effluents in China and other countries, the fecal coliform count is the only microbial indicator, raising concerns about the potential for pathogen transmission through WWTP effluent reuse. In this study, we collected 50 effluent samples (30 L/sample) from three municipal WWTPs in Shanghai, China, and analyzed for Cryptosporidium spp., Giardia duodenalis and Enterocytozoon bieneusi by microscopy and/or polymerase chain reaction (PCR). Moreover, propidium monoazide (PMA)-PCR was used to assess the viability of oocysts/cysts. The microscopy and PCR-positive rates for Cryptosporidium spp. were 62% and 40%, respectively. The occurrence rates of G. duodenalis were 96% by microscopy and 92-100% by PCR analysis of three genetic loci. Furthermore, E. bieneusi was detected in 70% (35/50) of samples by PCR. Altogether, 10 Cryptosporidium species or genotypes, two G. duodenalis genotypes, and 11 E. bieneusi genotypes were found, most of which were human-pathogenic. The chlorine dioxide disinfection employed in WWTP1 and WWTP3 failed to inactivate the residual pathogens; 93% of the samples from WWTP1 and 83% from WWTP3 did not meet the national standard on fecal coliform levels. Thus, urban WWTP effluents often contain residual waterborne human pathogens.

Enterocytozoon bieneusi genotypes in yaks (Bos grunniens) and their public health potential.

Enterocytozoon bieneusi, the most frequently diagnosed microsporidian species in humans, is also identified in a wide range of animals. To date, few data are available on E. bieneusi in yaks (Bos grunniens). In this study, we examined the occurrence and genotype identity of E. bieneusi in yaks in four counties in Qinghai Province of China. Of 327 fecal specimens examined by nested PCR analysis of the ribosomal internal transcribed spacer, 23 (7.0%) were E. bieneusi-positive. DNA sequence analysis of the PCR products revealed the presence of five distinct genotypes: three Group 2 genotypes previously reported in cattle as well as humans (BEB4, I and J) and two novel genotypes (CHN11 and CHN12) belonging to the large zoonotic group (Group 1). Data of the study suggest that these animals could be potential reservoirs for human E. bieneusi infection.

The bacteriome-coupled phage communities continuously contract and shift to orchestrate the traditional rice vinegar fermentation.

Amounts of microbiome studies have uncovered the microbial communities of traditional food fermentations, while in which the phageome development with time is poorly understood. Here, we conducted a study to decipher both phageome and bacteriome of the traditional rice vinegar fermentation. The vinegar phageomes showed significant differences in the alpha diversity, network density and clustering coefficient over time. Peduoviridae had the highest relative abundance. Moreover, the phageome negatively correlated to the cognate bacteriome in alpha diversity, and undergone constantly contracting and shifting across the temporal scale. Nevertheless, 257 core virial clusters (VCs) persistently occurred with time whatever the significant impacts imposed by the varied physiochemical properties. Glycoside hydrolase (GH) and glycosyltransferase (GT) families genes displayed the higher abundances across all samples. Intriguingly, diversely structuring of toxin-antitoxin systems (TAs) and CRISPR-Cas arrays were frequently harbored by phage genomes. Their divergent organization and encoding attributes underlie the multiple biological roles in modulation of network and/or contest of phage community as well as bacterial host community. This phageome-wide mapping will fuel the current insights of phage community ecology in other traditional fermented ecosystems that are challenging to decipher.

Ningxin-Tongyu-Zishen formula alleviates the senescence of granulosa cells on D-galactose-induced premature ovarian insufficiency mice.

Ningxin-Tongyu-Zishen formula (NTZF) is a clinical experience formula for the treatment of premature ovarian insufficiency (POI) in traditional Chinese medicine (TCM), and the potential mechanism is unknown. For in vivo experiments, POI mouse models (C57BL/6 mice), were constructed by subcutaneous injection of D-galactose (D-gal, 200 mg/kg). After treatment of NTZF (10.14, 20.27, 40.54 g/kg;) or estradiol valerate (0.15 mg/kg), ovarian function, oxidative stress (OS) and protein expression of Sirt1/p53 were evaluated. For in vitro experiments, H2O2 (200 µM) was used to treat KGN to construct ovarian granulosa cells (OGCs) cell senescence model. Pretreatment with NTZF (1.06 mg/mL) or p53 inhibitor (Pifithrin-α, 1 µM) was performed before induction of senescence, and further evaluated the cell senescence, OS, mRNA and protein expression of Sirt1/p53. In vivo, NTZF improved ovarian function, alleviated OS and Sirt1/p53 signaling abnormalities in POI mice. In vitro experiments showed that NTZF reduced the level of OS and alleviated the senescence of H2O2-induced KGN. In addition, NTZF activated the protein expression of Sirt1, inhibited the mRNA transcription and protein expression of p53 and p21. Alleviating OGCs senescence and protecting ovarian function through Sirt1/p53 is one of the potential mechanisms of NTZF in the treatment of POI.

Advances in the structural characterization of complexes of therapeutic antibodies with PD-1 or PD-L1.

Antibody-based immune checkpoint blockade (ICB)-based therapeutics have become effective clinical applications for cancers. Applications of monoclonal antibodies (mAbs) to de-activate the PD-1-PD-L1 pathway could effectively reverse the phenotype of depleted activated thymocytes (T cells) to recover their anti-tumoral activities. High-resolution structures of the complexes of the therapeutic monoclonal antibodies with PD-1 or PD-L1 have revealed the key inter-molecular interactions and provided valuable insights into the fundamental mechanisms by which these antibodies inhibit PD-L1-PD-1 binding. Each anti-PD-1 mAb exhibits a unique blockade mechanism, such as interference with large PD-1-PD-L1 contacting interfaces, steric hindrance by overlapping a small area of this site, or binding to an N-glycosylated site. In contrast, all therapeutic anti-PD-L1 mAbs bind to a similar area of PD-L1. Here, we summarized advances in the structural characterization of the complexes of commercial mAbs that target PD-1 or PD-L1. In particular, we focus on the unique characteristics of those mAb structures, epitopes, and blockade mechanisms. It is well known that the use of antibodies as anti-tumor drugs has increased recently and both PD-1 and PD-L1 have attracted substantial attention as target for antibodies derived from new technologies. By focusing on structural characterization, this review aims to aid the development of novel antibodies targeting PD-1 or PD-L1 in the future.

Comprehensive deciphering prophages in genus Acetobacter on the ecology, genomic features, toxin-antitoxin system, and linkage with CRISPR-Cas system.

Acetobacter is the predominant microbe in vinegar production, particularly in those natural fermentations that are achieved by complex microbial communities. Co-evolution of prophages with Acetobacter, including integration, release, and dissemination, heavily affects the genome stability and production performance of industrial strains. However, little has been discussed yet about prophages in Acetobacter. Here, prophage prediction analysis using 148 available genomes from 34 Acetobacter species was carried out. In addition, the type II toxin-antitoxin systems (TAs) and CRISPR-Cas systems encoded by prophages or the chromosome were analyzed. Totally, 12,000 prophage fragments were found, of which 350 putatively active prophages were identified in 86.5% of the selected genomes. Most of the active prophages (83.4%) belonged to the order Caudovirales dominated by the families Siphoviridae and Myroviridae prophages (71.4%). Notably, Acetobacter strains survived in complex environments that frequently carried multiple prophages compared with that in restricted habits. Acetobacter prophages showed high genome diversity and horizontal gene transfer across different bacterial species by genomic feature characterization, average nucleotide identity (ANI), and gene structure visualization analyses. About 31.14% of prophages carry type II TAS, suggesting its important role in addiction, bacterial defense, and growth-associated bioprocesses to prophages and hosts. Intriguingly, the genes coding for Cse1, Cse2, Cse3, Cse4, and Cas5e involved in type I-E and Csy4 involved in type I-F CRISPR arrays were firstly found in two prophages. Type II-C CRISPR-Cas system existed only in Acetobacter aceti, while the other Acetobacter species harbored the intact or eroded type I CRISPR-Cas systems. Totally, the results of this study provide fundamental clues for future studies on the role of prophages in the cell physiology and environmental behavior of Acetobacter.

Atomically dispersed Ru catalysts for polychlorinated aromatic hydrocarbon oxidation.

The development of cost-efficient catalysts with good catalytic activity is an urgent task for polychlorinated aromatic hydrocarbon (PCAH) oxidation. Herein, atomically dispersed Ru catalysts (denoted as Ru ADCs) proved by aberration corrected high-angle annular dark-field scanning transmission electron microscopy and X-ray absorption spectroscopy were synthesized for PCAH oxidation. The oxidation results showed that 0.2 Ru ADCs exhibited enhanced catalytic activity (T50% < 250 °C, T90% < 300 °C) compared with the T90% > 300 °C on 0.2 Ru nanoparticles (NPs). Besides, 0.2 Ru ADCs demonstrated high CO2 yield with >60% CO2 ratio, along with good stability (>80% conversion for 800 mins). The better performance of 0.2 Ru ADCs was verified by kinetic experiments, in which, the apparent activation energy associated with 0.2 Ru ADCs (50.8 kJ mol-1) was significantly lower compared with that with 0.2 Ru NPs (80.0 kJ mol-1). The superior oxidation activity of 0.2 Ru ADCs was also applied to toluene oxidation. H2 temperature-programmed reduction ensured the stronger interaction of Ru species with the supports in Ru ADCs than that in Ru NPs, thus inhibiting Ru species aggregation and favoring their higher dispersion ensured by CO temperature-programmed desorption. The present work provides a potential strategy to maximize the usage of noble metal catalysts for PCAH oxidation.

Restoring mammary gland structures and functions with autogenous cell therapy.

In somatic cell reprogramming, cells must escape the somatic cell-specific gene expression program to adopt other cell fates. Here, in vitro chemical induction with RepSox generated chemically induced mammary epithelial cells (CiMECs) with milk secreting functions from goat ear fibroblasts (GEFs). Transplanted CiMECs regenerated the normal mammary gland structure with milk-secreting functions in nude mice. Single-cell RNA sequencing revealed that during the reprogramming process, GEFs may sequentially undergo embryonic ectoderm (EE)-like and different MEC developmental states and finally achieve milk secreting functions, bypassing the pluripotent state. Mechanistically, Smad3 upregulation induced by transforming growth factor ß (TGFß) receptor 1 (TGFßR1) downregulation led to GEF reprogramming into CiMECs without other reprogramming factors. The TGFßR1-Smad3 regulatory effects will provide new insight into the TGFß signaling pathway regulation of somatic cell reprogramming. These findings suggest an innovative strategy for autogenous cell therapy for mammary gland defects and the production of transgenic mammary gland bioreactors.

Serum MyomiRs as Biomarkers for Female Carriers of Duchenne/Becker Muscular Dystrophy.

Background: Duchenne/Becker muscular dystrophy (DMD/BMD) is an X-linked recessive lethal neuromuscular disease. MicroRNAs expressed in striated muscle, myomiRs, have been proposed as its potential biomarkers. Serum creatine kinase (CK) is commonly used as a biomarker in clinical practice, but it is not reliable. The aim of this study was to assess whether serum levels of myomiRs has diagnostic value for detection of female DMD/BMD carriers with normal or elevated CK. Methods: Thirty four female carriers and 33 age-matched healthy female controls were enrolled. Peripheral blood samples were collected and serum miRNAs were extracted for measurement of miR-1, miR-133a, miR-133b, miR-206, miR-208a, miR-208b, and miR-499 by quantitative real-time polymerase chain reaction. Results: MiR-1, miR-133a, miR-133b, miR-206, miR-208a, miR-208b, and miR-499 were upregulated in all female carriers in comparison to healthy controls. MiR-1 (Spearman's rho = +0.406, p = 0.017) was correlated with CK in the female carrier group. Receiver operating characteristic curve analysis of all seven myomiRs showed that the area under the curve (AUC) for miR-499, miR-133b, miR-1, miR-208b, and miR-133a exceeded 70.0%, and for miR-206 and miR-208a exceeded 60.0%. MiR-133b and miR-499 were significantly increased in all female carriers, even those with normal CK. AUC for the combination of all seven miRNAs was 87.2%. CK (OR 0.406, 95% CI 0.000-0.001, p < 0.0001) and miR-499 (OR 0.323, 95% CI 0.023-0.106, p = 0.003) were considered to be independent predictors for female carriers presence in the multivariable regression analysis model. Conclusions: MiR-133b and miR-499 are potentially useful biomarkers for female carriers with DMD/BMD (including those with normal CK). The combination of all seven serum miRNAs and their respective combinations with CK have better diagnostic value for female carriers than either CK or any separate miRNA.

Corrigendum: Serum MyomiRs as Biomarkers for Female Carriers of Duchenne/Becker Muscular Dystrophy.

[This corrects the article DOI: 10.3389/fneur.2020.563609.].

Improved Risk Prediction Calculator for Sentinel Node Positivity in Patients With Melanoma: The Melanoma Institute Australia Nomogram.

PURPOSE: For patients with primary cutaneous melanoma, the risk of sentinel node (SN) metastasis varies according to several clinicopathologic parameters. Patient selection for SN biopsy can be assisted by National Comprehensive Cancer Network (NCCN) and ASCO/Society of Surgical Oncology (SSO) guidelines and the Memorial Sloan Kettering Cancer Center (MSKCC) online nomogram. We sought to develop an improved online risk calculator using alternative clinicopathologic parameters to more accurately predict SN positivity. PATIENTS AND METHODS: Data from 3,477 patients with melanoma who underwent SN biopsy at Melanoma Institute Australia (MIA) were analyzed. A new nomogram was developed by replacing body site and Clark level from the MSKCC model with mitotic rate, melanoma subtype, and lymphovascular invasion. The predictive performance of the new nomogram was externally validated using data from The University of Texas MD Anderson Cancer Center (n = 3,496). RESULTS: The MSKCC model receiver operating characteristic curve had a predictive accuracy of 67.7% (95% CI, 65.3% to 70.0%). The MIA model had a predictive accuracy of 73.9% (95% CI, 71.9% to 75.9%), a 9.2% increase in accuracy over the MSKCC model (P < .001). Among the 2,748 SN-negative patients, SN biopsy would not have been offered to 22.1%, 13.4%, and 12.4% based on the MIA model, the MSKCC model, and NCCN or ASCO/SSO criteria, respectively. External validation generated a C-statistic of 75.0% (95% CI, 73.2% to 76.7%). CONCLUSION: A robust nomogram was developed that more accurately estimates the risk of SN positivity in patients with melanoma than currently available methods. The model only requires the input of 6 widely available clinicopathologic parameters. Importantly, the number of patients undergoing unnecessary SN biopsy would be significantly reduced compared with use of the MSKCC nomogram or the NCCN or ASCO/SSO guidelines, without losing sensitivity. An online calculator is available at www.melanomarisk.org.au.

Dominant genera of cyanobacteria in Lake Taihu and their relationships with environmental factors.

Cyanobacterial blooms in freshwaters have become one of the most widespread of environmental problems and threaten water resources worldwide. Previous studies on cyanobacteria in Lake Taihu often collected samples from one site (like Meiliang Bay or Zhushan Bay) and focused on the variation in patterns or abundance of Microcystis during the blooming season. However, the distribution of cyanobacteria in Lake Taihu shows differing pattern in various seasons. In this study, water samples were collected monthly for one year at five sites in Lake Taihu with different trophic status and a physicochemical analysis and denaturing gradient gel electrophoresis (DGGE) were conducted. DGGE fingerprint analysis showed that Microcystis (7/35 bands) and Synechococcus (12/35 bands) were the two most dominant genera present during the study period at all five sites. Cyanobium (3/35 bands) was the third most common genus which has seldom been previously reported in Lake Taihu. Redundancy analysis (RDA) indicated that the cyanobacterial community structure was significantly correlated with NO3 (-)-N, CODMn, and NH4 (+)-N in the winter and spring, whereas it was correlated with water temperature in the summer and autumn. Limiting the nutrient input (especially of N and C loading) in Lake Taihu would be a key factor in controlling the growth of different genera of cyanobacteria.

Distribution of Cryptosporidium species in Tibetan sheep and yaks in Qinghai, China.

Few data are available on the distribution of Cryptosporidium species in Tibetan sheep and yaks, which are free-range animals living in a cold, low oxygen, and high ultraviolet radiation habitat. In this study, 904 fecal specimens were collected from 350 Tibetan sheep and 554 yaks in six counties. Cryptosporidium spp. were detected and differentiated by PCR and sequence analyses. Altogether, 43 (12.3%) Tibetan sheep and 158 (28.5%) yaks were positive for Cryptosporidium spp. In Tibetan sheep, Cryptosporidium xiaoi (39/43, 90.7%) was the dominant species, with the remaining cases (4/43, 9.3%) by Cryptosporidium ubiquitum. All C. ubiquitum specimens belonged to the subtype family XIIa. In contrast, Cryptosporidium andersoni (72/158, 45.6%), Cryptosporidium bovis (47/158, 29.7%), Cryptosporidium ryanae cattle type (35/158, 22.2%), C. ryanae buffalo type (2/158, 1.3%), and Cryptosporidium suis-like (2/158, 1.3%) were identified in yaks. Contradictory to previous observations, C. andersoni was one of the dominant Cryptosporidium species in yaks in this study. Despite sharing habitats, Tibetan sheep and yaks are evidently infected with different Cryptosporidium species.

Biosorption and biodegradation of triphenyltin by Stenotrophomonas maltophilia and their influence on cellular metabolism.

Triphenyltin (TPT), an endocrine disruptor, is polluting the global environment through its worldwide use. However, information concerning the mechanisms of TPT biodegradation and cellular metabolism is severely limited. Therefore, these processes were elucidated through experiments involving TPT biosorption and degradation, intracellular metabolite analysis, nutrient use, ion and monosaccharide release, cellular membrane permeability and protein concentration quantification. The results verified that TPT was initially adsorbed by the cell surface of Stenotrophomonas maltophilia and was subsequently transported and degraded intracellularly with diphenyltin and monophenyltin production. Cl(-), Na(+), arabinose and glucose release, membrane permeability and the extracellular protein concentration increased during TPT treatment, whereas K(+) and PO4(3-) utilization and intracellular protein concentration declined. The biosorption, degradation and removal efficiencies of TPT at 0.5mgL(-1) by 0.3gL(-1) viable cells at 10 d were 3.8, 77.8 and 86.2%, respectively, and the adsorption efficiency by inactivated cells was 72.6%.

Occurrence and molecular characterization of Cryptosporidium spp. in yaks (Bos grunniens) in China.

Compared with dairy and beef cattle, few data are available on the occurrence and distribution of Cryptosporidium species in yaks, which live in a very different habitat. In this study, 327 fecal specimens were collected from yaks in 4 counties in Qinghai Province of China and screened for Cryptosporidium by nested PCR analysis of the 18S rRNA gene. A total of 98 (30.0%) specimens were positive for Cryptosporidium. The occurrence of Cryptosporidium varied significantly among age groups; infection rates were 49.3% in weaned calves, 31.7% in yearlings, and 17.4% in adults. PCR products of all Cryptosporidium-positive specimens were successfully sequenced, with 56 specimens (57.1%) having C. bovis, 33 (33.7%) having C. ryanae, 2 (2.0%) having C. andersoni, 1 (1.0%) having C. ubiquitum, 1 (1.0%) having C. xiaoi, 2 (2.0%) having a novel genotype, and 3 (3.1%) having mixed infections of C. bovis and C. ryanae. There were some age-related differences in the distribution of Cryptosporidium species in post-weaned yaks examined. To our knowledge, this is the first report of C. andersoni, C. ubiquitum, C. xiaoi and a novel Cryptosporidium genotype in yaks.

[Enhancing effect of Tween 80 on degradation of triphenyltin by Bacillus thuringiensis].

So far, the information regarding enhanced degradation and biodegradation mechanisms of TPhT, an endocrine disruptor, is severely limited. Whether dearylation during TPhT degradation occurs successively or synchronously is not revealed clearly. To deal with these problems, this study focused on the biodegradation of TPhT and its metabolites by Bacillus thuringiensis through the acceleration of Tween 80. The results showed that Tween 80 obviously increased the TPhT solubility. After degradation by cells in the presence of 80 mg L-1 Tween 80 for 2 d, the residual TPhT at 1 mg L-1 initially was decreased to 48.4%. During the biodegradation process, Tween 80 significantly reduced intracellular Na+, NH+4: and Mg2+ release, and increased extracellular Cl- , PO(3-)4 and K+ utilization. Metabolites analysis revealed that phenyltin biodegradation initially proceeded by cleaving the aromatic ring, not by splitting the covalent bonds between the benzene rings and tin atom. Ring-cleavage reactions in the benzenes of TPhT occurred individually and synchronously, producing diphenyltin, monophenyltin and tin accordingly.