Appropriate chicken sample size for identifying the composition of broiler intestinal microbiota affected by dietary antibiotics, using the polymerase chain reaction-denaturing gradient gel electrophoresis technique

The bacterial microbiota in the broiler gastrointestinal tract are crucial for chicken health and growth. Their composition can vary among individual birds. To evaluate the composition of chicken microbiota in response to environmental disruption accurately, 4 different pools made up of 2, 5, 10, and 15 individuals were used to determine how many individuals in each pool were required to assess the degree of variation when using the PCR-denaturing gradient gel electrophoresis (DGGE) profiling technique. The correlation coefficients among 3 replicates within each pool group indicated that the optimal sample size for comparing PCR-DGGE bacterial profiles and downstream applications (such as identifying treatment effects) was 5 birds per pool for cecal microbiota. Subsequently, digesta from 5 birds was pooled to investigate the effects on the microbiota composition of the 2 most commonly used dietary antibiotics (virginiamycin and bacitracin methylene disalicylate) at 2 different doses by using PCR-DGGE, DNA sequencing, and quantitative PCR techniques. Thirteen DGGE DNA bands were identified, representing bacterial groups that had been affected by the antibiotics. Nine of them were validated. The effect of dietary antibiotics on the microbiota composition appeared to be dose and age dependent. These findings provide a working model for elucidating the mechanisms of antibiotic effects on the chicken intestinal microbiota and for developing alternatives to dietary antibiotics.

Synergistic effect between EGF and TGF-beta1 in inducing oncogenic properties of intestinal epithelial cells

Transforming growth factor (TGF)-beta1 has a biphasic effect on rat intestinal epithelial (RIE) cells. By itself, TGF-beta1 functions as a tumor suppressor by inhibiting the growth, migration and invasion of RIE cells. We show in this study that in conjunction with epidermal growth factor (EGF), TGF-beta1 helped to augment migration, invasion and anchorage-independent growth (AIG) compared to that by EGF alone. EGF plus TGF-beta1 induced a dramatic morphological change characteristic of epithelial-mesenchymal transition (EMT). The mechanism for this enhanced effect of TGF-beta1 and EGF on oncogenic properties was explored by analysis of EGF- and TGF-beta1-mediated signaling pathways and complementary DNA arrays. TGF-beta1 augmented EGF-mediated signaling of mitogen-activated protein kinase (MAPK) and AKT by enhancing and prolonging the activation of the former and prolonging the activation of the latter. Inhibition of MAPK, but not phosphoinositide-3 kinase (PI3K), abolished TGF-beta1 plus EGF-induced EMT and downregulation of E-cadherin at mRNA and protein levels. By contrast, cell migration and invasion were sensitive to inhibition of either MAPK or PI3 kinase. TGF-beta1 plus EGF-induced AIG was significantly more resistant to inhibition of PI3K and MAPK compared to that induced by EGF alone. EGF and TGF-beta1 synergistically induced the expression of a series of proteases including matrix metalloproteinase (MMP) 1 (collagenase), MMP3, MMP9, MMP10, MMP14 and cathepsin. Among them, the expression of MMP1, MMP3, MMP9 and MMP10 was MAPK dependent. Inhibition of the MMPs or cathepsin significantly blocked EGF plus TGF-beta1-induced invasion, but had no effect on colony formation. Phospholipase C (PLC) and Cox2 induced by EGF plus TGF-beta1 also played a significant role in invasion, whereas PLC was also important for colony formation. Our study reveals specific signaling functions and induction of genes differentially required for enhanced effect of EGF- and TGF-beta1-induced oncogenic properties, and helps to explain the tumor-promoting effect of TGF-beta1 in human cancer with elevated expression or activation of TGF-beta1 and receptor protein tyrosine kinases.

In vitro assessment of antimicrobial activity of carvacrol, thymol and cinnamaldehyde towards Salmonella serotype Typhimurium DT104: effects of pig diets and emulsification in hydrocolloids

AIMS

To determine the effect of pig diets in vitro on the antimicrobial activity of carvacrol, thymol and cinnamaldehyde, and to identify an emulsifier/stabilizer that can stabilize the essential oil (EO) components in aqueous solution and retain their antimicrobial activity in the presence of the diets.

METHODS AND RESULTS

Emulsification of essential oil components with hydrocolloid solution was achieved by blending with a Polytron. Antimicrobial activity was measured through in vitro assays to determine the inhibition of bacterial growth by measuring the optical density at 600 nm or plating on nutrition agar after incubation of the mixtures of an EO component with the culture of Salmonella serotype Typhimurium DT104 in the presence or absence of pig diets. The results generated through the in vitro assays indicated that pig diets were able to abolish the antimicrobial activity of EOs. Xanthan, fenugreek and yellow mustard gums were the best in forming stable emulsions of five different EO components among ten different plant polysaccharides and surfactants examined. Emulsification of all the EO components in the fenugreek gum solution did not alter their antimicrobial activity. However, the antimicrobial activity of geraniol was significantly reduced when emulsified with other polysaccharides and surfactants. Both fenugreek and xanthan gum solutions were unable to protect the antimicrobial activity of carvacrol and thymol when mixed with the diets. Although cinnamaldehyde required no emulsification, but a high concentration (equivalent to at least three times of minimum bactericidal concentration for cinnamon oil) to inhibit Salmonella growth significantly in the presence of the diets, emulsification in fenugreek gum appeared to be essential for cinnamaldehyde solution to retain its antimicrobial activity during storage.

CONCLUSIONS

The diets for newly weaned pigs were a significant factor limiting the antimicrobial activity of EOs and their components. Cinnamaldehyde required a high concentration to retain its antimicrobial activity in the diets, in addition to its requirement for emulsification to stabilize its activity during the storage.

SIGNIFICANCE AND IMPACT OF THE STUDY

The assay with the diets used in this study for measuring the antimicrobial activity can be used in vitro for rapid and effective screening of potential antimicrobials for swine production. This study has identified polysaccharides that are able to stabilize EO component solutions. It has also identified cinnamaldehyde for further in vivo studies that may have potential in future application in controlling Salmonella and possibly other enteric pathogens in swine production.

Influence on intestinal mucous permeation of paclitaxel of absorption enhancers and dosage forms based on electron spin resonance spectroscopy

The aim of this paper is to investigate the permeation mechanism of the hydrophobic drug, paclitaxel in intestinal membranes of mice in relation to enhancers and preparation factors. The alteration fluidity of lipid and protein in mucous membrane were determined using electron spin resonance (ESR) when the membrane was treated with several enhancers including Pluronic F68, polyethylene glycol (PEG), Brij78 and lecithin. At the same time, the enhanced permeation of paclitaxel across the intestinal intercellular membrane of stratum corneum was studied for three formulations: inclusion complex, microemulsion and injection. The results showed that use of paclitaxel-hydroxypropyl-beta-cyclodextrin inclusion complexation and of paclitaxel microemulsion as vehicle and PEG 1500 as enhancer could significantly increase the permeation kinetics of paclitaxel in a fluid diffusion study. The effect on absorption characteristics of enhancing permeation of this hydrophobic drug in the intestinal mucosa was considered in the light of the change in membrane fluid.

Molecular epidemiologic analysis of group A rotaviruses in adults and children with diarrhea in Wuhan city, China, 2000-2006

To compare epidemiologic features and genetic characteristics of group A rotaviruses causing diarrhea in children and adults, a survey was conducted in Wuhan, China, during the period of Dec. 2000-May 2006. A total of 3839 stool specimens from diarrheal patients from eight hospitals were analyzed. Winter seasonality was observed for rotavirus diarrhea in both adults and children, showing overall rotavirus-positive rates of 9.0 and 23.9%, respectively. Throughout the study period, G3 was the most frequent G serotype in both adults and children (detection rates 86.2 and 87.8%, respectively), and was mostly associated with VP4 genotype P[8], VP 6 genotype II (subgroup II), and NSP4 genotype B. G3 rotaviruses were differentiated into eight electropherotypes, among which seven types were found in specimens from both adults and children. VP7 gene sequences of G3 rotaviruses from adults and children (6 and 4 strains, respectively), detected in different years and different hospitals, showed extremely high sequence identities (99-100%) to each other and to a few G3 rotavirus strains reported in Asia. However, lower sequence identities (82-96%) were observed to most of the human and animal G3 rotaviruses reported so far, including some Chinese strains. These findings indicate that in Wuhan, China, epidemic and genetic features of rotaviruses are similar in adults and children, and it has been suggested that G3 rotaviruses that might have originated from the same rotavirus were circulating among children and adults as prevailing viruses. In this study, two rotavirus strains, G9P[8] strain L169, derived from an adult, and G4P[6] strain R479, derived from a child, were isolated and genetically analyzed. The VP7 gene of L169 belongs to a major lineage of G9 rotaviruses that are globally widespread, but is distinct from G9 rotaviruses reported previously in China. The strain R479 had a VP7 gene which was divergent from most G4 human rotaviruses and showed an unusual dual subgroup specificity, I + II. The R479 VP6 gene does not belong to the main clusters of subgroup I and II rotaviruses phylogenetically, but is related to those of the porcine rotaviruses and some unusual human rotaviruses represented by the RMC321 strain isolated in eastern India.

Effect of pharmacological intakes of zinc and copper on growth performance, circulating cytokines and gut microbiota of newly weaned piglets challenged with coliform lipopolysaccharides

The effect of feeding pharmacological levels of zinc (Zn) and copper (Cu) to newly weaned piglets on growth performance, circulating cytokines levels and gut microbiota was investigated. One hundred eighty piglets [5.90 ± 0.18 kg body weight (BW); six pigs per pen] weaned at 16 to 19 d of age were fed diets containing 3000 ppm additional Zn, 250 ppm additional Cu or a control diet (150 ppm Zn, 15 ppm Cu) for 14 d post-weaning (weeks 1 and 2). Pigs were fed a control diet for an additional 2 wk. Pigs were injected intramuscularly on days 13 and 19 with either 75 μg kg-1 BW of coliform lipopolysaccharide (LPS) or an equivalent amount of saline. Blood samples were collected 3 h after LPS injection to measure plasma levels of cytokines and cortisol. Digesta of ileum and colon were collected from non-challenged pigs on days 14 and 28 to evaluate microbiota using conventional culturing methods and polymerase chain reaction and denaturing gradient gel electrophoresis (PCRDGGE) analysis of the 16S rRNA genes. There were no interactive effects of diet and LPS challenge on growth performance (P > 0.10). Compared with the control, high dietary Zn and Cu increased (P < 0.01) average daily gain (ADG) during weeks 1 (0.125, 0.091 vs. 0.074 kg; P < 0.05) and 2 (0.240, 0.270 vs. 0.155 kg; P < 0.01) only. LPS injection reduced ADG during weeks 2 and 4 (P < 0.01). Dietary treatment did not affect feed efficiency (P > 0.10). Challenging pigs with LPS reduced (P < 0.01) feed efficiency during week 2, but increased (P < 0.05) feed efficiency during week 3. There were no interactive effects between diet and LPS on plasma cytokines levels, except for cortisol (P < 0.05). Plasma levels of cytokines (interleukin-1β, interferon-γ, tumour necrosis factor-α) and cortisol increased (P < 0.01) in pigs challenged with LPS. The high levels of dietary Zn and Cu reduced (P < 0.05) the increases in plasma cortisol level in LPS-challenged pigs at days 9 and 19. There were no differences among the dietary treatments in counts of coliforms and lactobacillus in the digesta from ileum and colon (P > 0.10). PCR-DGGE analysis showed that high levels of dietary Zn and particularly Cu significantly reduced the diversity of ileal microbiota. The effect on microbiota diversity was reversible when dietary Zn and Cu were removed. Enhanced growth performance of the newly weaned piglets fed high dietary Zn and Cu appears mediated via changes in gut microbiota as well as a reduced cortisol response following an immune challenge. Key words: Piglets, zinc, copper, lipopolysaccharide, gut microbiota, cytokines

Unscheduled CDK1 activity in G1 phase of the cell cycle triggers apoptosis in X-irradiated lymphocytic leukemia cells

Cyclin-dependent kinase 1 (CDK1) is a major component of the cell cycle progression engine. Recently, several investigations provided evidence demonstrating that unscheduled CDK1 activation may also be involved in apoptosis in cancerous cells. In this article, we demonstrate that X-ray irradiation induced G1 arrest in MOLT-4 lymphocytic leukemia cells, the arrest being accompanied by reduction in the activity of CDK2, but increased CDK1 activity and cell apoptosis in the G1 phase. Interestingly, this increase in CDK1 and apoptosis by ionizing radiation was prevented by pretreatment with the CDK1 inhibitor, roscovitine, suggesting that CDK1 kinase activity is required for radiation-induced apoptotic cell death in this model system. Furthermore, cyclin B1 and CDK1 were detected co-localizing and associating in G1 phase MOLT-4 cells, with the cellular lysates from these cells revealing a genotoxic stress-induced increase in CDK1 phosphorylation (Thr-161) and dephosphorylation (Tyr-15), as analyzed by postsorting immunoprecipitation and immunoblotting. Finally, X-irradiation was found to increase Bcl-2 phosphorylation in G1 phase cells. Taken together, these novel findings suggest that CDK1 is activated by unscheduled accumulation of cyclin B1 in G1 phase cells exposed to X-ray, and that CDK1 activation, at the wrong time and in the wrong phase, may directly or indirectly trigger a Bcl-2-dependent signaling pathway leading to apoptotic cell death in MOLT-4 cells.

Beta-carotene supplementation increases antioxidant capacity of plasma in older women

The antioxidant effect of dietary beta-carotene supplementation on the peroxidation potential of plasma was investigated in a randomized double-blind, placebo-controlled study. Twelve healthy women (62-80 y) supplemented their usual daily diet with 90 mg of beta-carotene (n = 6) or placebo (n = 6) capsules for 3 wk. Plasma concentrations of beta-carotene, alpha- and gamma-tocopherol, ascorbate, urate, bilirubin and in vitro production of phosphatidylcholine hydroperoxides (PC-OOH) and utilization of plasma antioxidants in the presence of 50 mmol/L 2,2'-azobis (2-aminopropane) hydrochloride (AAPH), a free radical generator, at 37 degrees C were measured before and after dietary treatment. Plasma beta-carotene increased from 0.76 +/- 0.16 to 6.45 +/- 1.16 micromol/L (P < 0.05) in supplemented but not placebo-treated subjects. The plasma concentrations of other antioxidants did not change significantly in either group. beta-Carotene supplementation did not affect basal levels of plasma PC-OOH as measured by HPLC post-column chemiluminescence but did affect AAPH-induced production of PC-OOH. Before supplementation, the induction period of plasma PC-OOH production was 2.4 +/- 0.4 h, with levels reaching 5.39 +/- 1.50 micromol/L after 6 h of incubation. After supplementation, the induction period increased significantly to 4.2 +/- 0.4 h (P < 0.01), with a lower PC-OOH production of 2.16 +/- 0.90 micromol/L after 6 h (P < 0.05). In this system, plasma ascorbate concentrations were depleted first, followed by loss of bilirubin and alpha-tocopherol and then by the sequential loss of gamma-tocopherol, urate and beta-carotene. These results indicate that beta-carotene supplementation increases the plasma antioxidant capacity of older women.

Are private school students more likely to smoke than public school students in China?

BACKGROUND

Tobacco use is prevalent among adolescents in China in general, however, little is known about tobacco use among students in private schools with an enrollment of 1.5 million.

METHOD

In 2001, cross-sectional survey data from 2725 students in grades seven and eight (1307 sampled from private schools and 1418 sampled from public schools) were included. Smoking measures (risk of susceptibility to smoking, smoking onset, ever smoking, smoking in the past 7 days and past 30 days, established smoking) were compared between private and public school students using chi-square test, logistic regression, and survival analysis.

RESULTS

Cigarette smoking was more prevalent among private school students than among public school students (private vs. public: 21.9% vs. 12.3% for susceptibility to smoking, 53.9% vs. 38.2% for ever smoking, 22% vs. 12.0% for 30-day smoking, 15.9% vs. 4.0% for 7-day smoking, 4.5% vs. 1.2% for established smoking). Students in private schools are 3.4 to 3.8 times more likely to smoke than students in public schools after the adjustment of important covariates (gender, grade, peer smoking, parental smoking, and parents' occupation). Risk of smoking onset by age was also greater for private school students than for public school students.

CONCLUSIONS

Being in private schools was associated with three to four times increases in the likelihood of current cigarette smoking and heightened risk of smoking onset by age. Findings from this study suggest the urgent need to collect additional data on risk and protective factors as well as the willingness to participate in effective tobacco use intervention prevention among private school students.

Activation of p300 histone acetyltransferase activity and acetylation of the androgen receptor by bombesin in prostate cancer cells

Androgen receptor signaling in prostate cancer cells is augmented by the androgen receptor (AR) coactivator p300, which transactivates and acetylates the AR in the presence of dihydrotestosterone (DHT). As prostate cancer (PC) cells progress to androgen independence, AR signaling remains intact, indicating that other factors stimulate AR activities in the absence of androgen. We previously reported that neuropeptide growth factors could transactivate the AR in the presence of very low concentrations of DHT. Here, we examine the involvement of p300 in neuropeptide activation of AR signaling. Transfection of increasing concentrations of p300 in the presence of bombesin into PC-3 cells resulted in a linear increase in AR transactivation, suggesting that p300 acts as a coactivator in neuropeptide-mediated AR transactivation. P300 is endowed with histone acetyltransferase (HAT) activity. Therefore, we examine the effect of bombesin on p300 HAT activity. At 4 h after the addition of bombesin, p300 HAT activity increased 2.0-fold (P<0.01). Incubation with neutral endopeptidase, which degrades bombesin, or bombesin receptor antagonists blocked bombesin-induced p300 HAT activity. To explore the potential signaling pathways involved in bombesin-induced p300 HAT activity, we examined Src and PKCdelta pathways that mediate bombesin signaling. Inhibitors of Src kinase activity or Src kinase siRNA blocked bombesin-induced p300 HAT activity, whereas PKCdelta inhibitors or PKCdelta siRNA significantly increased bombesin-induced p300 HAT activity suggesting that Src kinase and PKCdelta kinase are involved in the regulation of p300 HAT activity. As AR is acetylated in the presence of 100 nM DHT, we next examined whether bombesin-induced p300 HAT activity would result in enhanced AR acetylation. Bombesin-induced AR acetylation at the same motif KLKK observed in DHT-induced acetylation. Elimination of p300 using p300 siRNA reduced AR acetylation, demonstrating that AR acetylation was mediated by p300. AR acetylation results in AR transactivation and the expression of the AR-regulated gene prostate-specific antigen (PSA). Therefore, we examined bombesin-induced AR transactivation and PSA expression in the presence and absence of p300 siRNA and found inhibition of p300 expression reduced bombesin-induced AR transactivation and PSA expression. Together these results demonstrate that bombesin, via Src and PKCdelta signaling pathways, activates p300 HAT activity which leads to enhanced acetylation of AR resulting in increased expression of AR-regulated genes.

Efficacy of radio frequency cooking in the reduction of Escherichia coli and shelf stability of ground beef

The effectiveness of radio frequency (RF) cooking on the inactivation of Escherichia coli in ground beef and its effect on the shelf stability of ground beef were investigated with a comparison to hot water-bath cooking. E. coli K12 was used as a target bacterium instead of E. coli O157:H7. The ground beef samples inoculated with E. coli K12 (ampr) were heated until the centre temperature of each sample reached 72 degrees C. These samples were then stored at 4 degrees C for up to 30 days. The enumeration of E. coli K12, background E. coli and coliform counts in ground beef samples was carried out for shelf-life study. Although both methods significantly reduced E. coli K12 (ampr), E. coli and coliform counts and extended the shelf-life, RF cooking had a shorter cooking time, and more uniform heating. Thus, RF cooking of meat has a high potential as a substitute for the hot water-bath cooking.

Defining spatial parameters for non-linear walking

Current definitions of the spatial and temporal parameters of gait have been based on the premise that walking occurs in a straight line. When the direction of progression (DoP) is not consistent and walking is non-linear, these definitions do not provide meaningful information. An alternative method based on the changing direction of each stride is presented. This method is easy to understand and use, and requires no expensive technology. A comparison of the spatial parameters of the footstep pattern during linear trials and trials incorporating a 60 degrees turn was performed, using output derived from the old and the new definitions. The two methods produced very different results. Spatial output from the old definitions was merely dictated by the change of direction. Output calculated relative to the changing stride direction however, provided useful information about the footstep adjustments made for turning and how these would act to improve stability. This method of establishing spatial parameters during non-linear walking should form a useful tool for further investigation of functional locomotion.

Antimicrobial activity of essential oils and structurally related synthetic food additives towards selected pathogenic and beneficial gut bacteria

AIMS

To assess the potential of essential oils and structurally related synthetic food additives in reducing bacterial pathogens in swine intestinal tract.

METHODS AND RESULTS

The antimicrobial activity of essential oils/compounds was measured by determining the inhibition of bacterial growth. Among 66 essential oils/compounds that exhibited > or =80% inhibition towards Salmonellatyphimurium DT104 and Escherichia coli O157:H7, nine were further studied. Most of the oils/compounds demonstrated high efficacy against S. typhimurium DT104, E. coli O157:H7, and E. coli with K88 pili with little inhibition towards lactobacilli and bifidobacteria. They were also tolerant to the low pH. When mixed with pig cecal digesta, these oils/compounds retained their efficacy against E. coli O157:H7. In addition, they significantly inhibited E. coli and coliform bacteria in the digesta, but had little effect on the total number of lactobacilli and anaerobic bacteria.

CONCLUSIONS

Some essential oils/compounds demonstrated good potential, including efficacy, tolerance to low pH, and selectivity towards bacterial pathogens, in reducing human and animal bacterial pathogens in swine intestinal tract.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study has identified candidates of essential oils/compounds for in vivo studies to develop antibiotic substitutes for the reduction of human and animal bacterial pathogens in swine intestinal tract.

The gastrointestinal microbiota and its role in monogastric nutrition and health with an emphasis on pigs: Current understanding, possible modulations, and new technologies for ecological studies

The gastrointestinal microbiota is an incompletely defined, dynamic community of several hundred species of primarily anaerobic bacteria. Species composition and bacterial numbers vary depending on animal age, the gastrointestinal location and a variety of nutritional and environmental factors. The microbiota positively and negatively impacts host physiology and performance in many important ways. This review will examine the establishment and composition of the normal microbiota; its beneficial and deleterious effects on the host; and methods by which to modify the microbiota. In addition, recent advances in methodology using the techniques of molecular biology to measure and describe the microbiota are discussed. Finally, recent results using the polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) technique to examine the microbiota of pigs at different ages, different intestinal sites, and after treatment with selected feed additives will be described. Key words: Microbiota, gastrointestinal tract, PCR-DGGE, animal nutrition/health, 16S rRNA

Melanoma inhibitor of apoptosis protein is expressed differentially in melanoma and melanocytic naevus, but similarly in primary and metastatic melanomas

BACKGROUND

Malignant melanoma is highly resistant to current treatments. The inhibitor of apoptosis protein (IAP) family member, melanoma IAP (ML-IAP), is overexpressed in some melanoma cell lines, rendering them resistant to apoptotic signals. Targeting ML-IAP is a promising approach to treating melanoma. However, the status of ML-IAP expression in human melanoma tissues and the difference in expression between melanoma and melanocytic naevus are not known.

AIMS

To investigate these issues.

METHODS

ML-IAP expression in 48 archived patient samples (34 melanomas and 14 dermal naevi) was assessed by immunohistochemistry and by in situ hybridisation and reverse transcription polymerase chain reaction (RT-PCR) assays developed for the study.

RESULTS

Expression of ML-IAP was detected in 47.6-70.6% (10 of 21 to 24 of 34) of the melanomas, varying with detection methods. The expression rate in melanoma was much higher than that in melanocytic naevus (10.0-21.4%; one of 10 to three of 14). No significant difference was seen between primary and secondary melanomas. ML-IAP expression rates assessed by the three methods were in agreement.

CONCLUSIONS

The ML-IAP expression rate in archived melanoma tissues is around 50-70%, with no difference between primary and secondary melanomas. A small number of dermal naevi ( approximately 20%) also expressed ML-IAP.

First Report of Alternaria raphani Causing Black Patches on Chinese Radish During Postharvest Storage in Canada

During November of 2003, Chinese radishes (Raphanus sativus cv. Taibai) harvested in St. Catharines, Ontario and stored in less than 1°C with 98% relative humidity (RH) and 5°C with 96% RH showed symptoms of black and dark brown, irregular patches, with or without decay. The symptoms were closely associated with skin wounds and damaged root hairs. Fungal DNA was extracted from discolored skin samples peeled from a radish, and 18S rRNA genes were amplified with fungal-specific PCR primers (1) EF4f (5'-ggaagggrtgtatttattag-3') and EF3r (5'-tcctctaaatgaccagtttg-3'). The cloned genes were sequenced using the primer EF4f and compared directly with nonredundant nucleotides in GenBank with BLAST. The results indicated that more than 75% of the fungal microflora on the diseased radish were Alternaria spp. Alternaria sp. was successfully isolated from discolored and decayed radish tissues. Morphological and molecular identification indicated that the isolated Alternaria sp. cultures belong to A. raphani, which was previously reported to cause leaf and pod blight on radish (2). For pathogenicity studies, a spore suspension (1 × 10⁵ conidia/ml) obtained from a 4-week-old A. raphani culture was used to inoculate 'Taibai' Chinese radish tissues, including inner tissues and wounded and nonwounded skin. All tests were carried out at room temperature (22 to 24°C). On inner tissue and wounded skin, symptoms of dark brown-to-black patches appeared 2 days after inoculation and progressed with time. No symptoms developed on the noninoculated control or the nonwounded, inoculated treatment. A. raphani was reisolated from symptomatic tissue. Further evidence of pathogenicity was obtained by an additional inoculation and observation of symptoms. The results indicated that A. raphani was the causal agent of the black patches observed on Chinese radish, and to our knowledge, this is the first report that A. raphani could cause a postharvest disease on Chinese radish in storage. References: (1) J. D. Van Elsas et al. J. Microbiol. Methods 43:133, 2000. (2) M. S. Sangwan et al. J. Mycol. Plant Pathol. 32:125, 2002.

Effects of perceived peer isolation and social support availability on the relationship between body mass index and depressive symptoms

OBJECTIVE

To examine relationships between body mass index (BMI) and psychological correlates in Chinese school adolescents during the period of economic transition.

DESIGN

Baseline data of 1655 Chinese adolescents aged 11-15 y were retrieved from a longitudinal smoking cessation and health promotion program in Wuhan, China. Assessments of body weight and height, depressive symptoms, perceived peer isolation (PPI) and perceived availability of social support (PASS) were collected.

RESULTS

Based on the International Obesity Task Force (IOTF) age-and sex-specific BMI cutoffs, 12.5% of boys and 9.2% of girls were overweight. In girls, high BMI was significantly related to higher self-reported depressive symptoms, and was dominantly mediated by PPI. On the contrary, high BMI boys reported significantly lower levels of PPI although high PPI level aggravated depressive symptoms. For both girls and boys, the observed effect of PPI on the relationship between BMI and depressive symptoms was sustained only in low PASS boys and girls.

CONCLUSIONS

The present study revealed different effects of PPI on the association of BMI and depressive symptoms between boys and girls, which were buffered by levels of PASS. The findings of this study may contribute to our understanding of the influences of psychological correlates in pediatric overweight in the Eastern cultural environment.

Domestic ruminants as models for the elucidation of the mechanisms controlling ovarian follicle development in humans

It is necessary to understand the basic physiology underlying the complex process of folliculogenesis to address common causes of infertility and to devise innovative strategies to increase the efficiency of assisted reproduction technologies. Availability of suitable ovarian tissue is a major constraint to research in this area in humans, and monovulatory domestic ruminants represent a physiologically relevant model to elucidate basic mechanisms before more focused clinical investigations. This paper reviews the development of several whole animal and cell culture models in ruminants that have allowed basic investigations into the endocrine and local mechanisms regulating preantral and antral follicle development in monovulatory species. Studies on preantral follicle development using the ovarian autograft model have shown, contrary to accepted dogma, that FSH may mediate the rate at which preantral follicles grow and have provided evidence to support the existence of local regulatory feedback mechanisms that influence the rate of primordial follicle initiation and preantral follicle development. Studies on the endocrine control of antral follicle development using the GnRH-antagonist model have shown that a pulsatile mode of LH delivery is not a requirement for normal patterns of follicle development and ovarian hormone secretion. Studies on the local control of somatic cell differentiation using physiological cell culture models have highlighted the essential relationship between somatic cell communication and expression of differentiative markers. We conclude that the domestic ruminant represents a valuable model system for the elucidation of the endocrine and local mechanisms controlling both early and terminal stages of follicle development in monovulatory species. The results of these investigations have direct strategic relevance within clinical medicine.