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Y J Hu

Publications and source records attributed to Y J Hu.

49 records · Page 3Linked to original sources
PubMed1992

Cloning and expression of an amylase gene from Streptococcus bovis in Escherichia coli.

An amylase gene was identified in a Streptococcus bovis 033 lambda gtWES lambda B genomic library. Using a starch overlay and a Congo red-iodine staining procedure, amylase positive clones could be identified by zones of clearing. Ten amylase positive clones were identified using this procedure. The clone chosen for further study, lambda SBA105, contained an insert of approximately 7.5 kb. The insert was mapped, and subcloning localized the amylase gene to a region of approximately 3.1 kb. Cloning of the 3.1 kb amylase fragment into pUC18 in both orientations revealed that the amylase gene was transcribed from its own promoter. Amylase activity was expressed by the Escherichia coli subclones and was found to be largely associated with the cytoplasmic fraction. Southern hybridization of genomic DNA from the amylolytic strains, S. bovis 033, S. bovis 077, Butyrivibrio fibrisolvens 194 and 195 revealed a single hybridizing band in S. bovis 033 DNA only. This indicates that the amylase gene from S. bovis may differ from the amylases of these other amylolytic bacteria.

Amylases↗
PubMed1991

Cloning of a xylanase gene from Fibrobacter succinogenes 135 and its expression in Escherichia coli.

A genomic library consisting of 4- to 7-kb EcoRI DNA fragments from Fibrobacter succinogenes 135 was constructed using a phage vector, lambda gtWES lambda B, and Escherichia coli ED8654 as the host bacterium. Two positive plaques, designated lambda FSX101 and lambda FSX102, were identified. The inserts were 10.5 and 9.8 kb, respectively. A 2.3-kb EcoRI fragment that was subcloned from lambda FSX101 into pBR322 also showed xylanase activity. Southern blot analysis showed that the cloned EcoRI fragment containing the xylanase gene had originated from F. succinogenes 135. The cloned endo-(1,4)-beta-D-xylanase gene (pFSX02) was expressed constitutively in E. coli HB101 when grown on LB and on M9 medium containing either glucose or glycerol as the carbon source. Most of the beta-D-xylanase activity was located in the periplasmic space. Zymogram activity stains of nondenaturing polyacrylamide gels and isoelectric focusing gels showed that several xylanase isoenzymes were present in the periplasmic fraction of the E. coli clone FSX02 and they probably were due to posttranslational modification of a single gene product. Comparison of the FSX02 xylanase and the xylanase from the extracellular culture fluids of F. succinogenes 135 and S85 for their ability to degrade oat spelt xylan showed that, for equal units of beta-D-xylanase activity, hydrolysis by the cloned gene product was more complete. However, unlike the unfractionated mixture of xylanases from F. succinogenes 135 and S85, the enzyme from E. coli FSX02 was unable to release arabinose from oat spelt xylan.

Animals↗
PubMed1990

[Preliminary study of peroxidlipid in edible oils and fats].

In this article we report that peroxidlipid in edible oil-fats is extracted by using thylene glycol and measured by using TBA colorimetric method. This method is simple, rapid and has a high degree of accuracy with CV of 4.5%. The contents of peroxidlipid have been studied for certain edible oil-fats before and after high heat. The results showed that the contents of LPO were markedly increased after high heating.

Fats, Unsaturated↗
PubMed1989

Cloning of a Thermomonospora fusca xylanase gene and its expression in Escherichia coli and Streptomyces lividans.

Thermomonospora fusca chromosomal DNA was partially digested with EcoRI to obtain 4- to 14-kilobase fragments, which were used to construct a library of recombinant phage by ligation with EcoRI arms of lambda gtWES. lambda B. A recombinant phage coding for xylanase activity which contained a 14-kilobase insert was identified. The xylanase gene was localized to a 2.1-kilobase SalI fragment of the EcoRI insert by subcloning onto pBR322 and derivatives of pBR322 that can also replicate in Streptomyces lividans. The xylanase activity produced by S. lividans transformants was 10- to 20-fold higher than that produced by Escherichia coli transformants but only one-fourth the level produced by induced T. fusca. A 30-kilodalton peptide with activity against both Remazol brilliant blue xylan and xylan was produced in S. lividans transformants that carried the 2.1-kilobase SalI fragment of T. fusca DNA and was not produced by control transformants. T. fusca cultures were found to contain a xylanase of a similar size that was induced by growth on xylan or Solka Floc. Antiserum directed against supernatant proteins isolated from a Solka Floc-grown T. fusca culture inhibited the xylanase activity of S. lividans transformants. The cloned T. fusca xylanase gene was expressed at about the same level in S. lividans grown in minimal medium containing either glucose, cellobiose, or xylan. The xylanase bound to and hydrolyzed insoluble xylan. The cloned xylanase appeared to be the same as the major protein in xylan-induced T. fusca culture supernatants, which also contained at least three additional minor proteins with xylanase activity and having apparent molecular masses of 43, 23, and 20 kilodaltons.

Bacteria↗
PubMed1988

Cloning of Thermomonospora fusca genes coding for beta 1-4 endoglucanases E1, E2 and E5.

Thermomonospora fusca chromosomal DNA was partially digested with EcoRI and fragments in the size range from 4 to 15 kb were isolated, ligated into lambda gtWES.lambda B arms, packaged, and the recombinant phages plated on Escherichia coli. The plaques were screened for carboxymethyl cellulase (CMCase) activity by a gel overlay procedure, and 25 plaques were positive among the 15,000 plaques that were screened. Positive phages were amplified and used to prepare infected E. coli extracts which were assayed for CMCase activity before and after treatment with antisera prepared against five purified T. fusca beta 1-4 endoglucanases (E1-E5). One phage produced an enzyme that was inhibited by E1 antiserum, nine of the phages produced enzymes that were inhibited by E2 antiserum, 14 produced enzymes that were inhibited by E5 antiserum and the enzyme produced by the other phages was not inhibited by any of the five antisera. The DNA insert present in the phage coding for E1 was cut into a number of different fragments which were subcloned into E. coli first using lambda gtWES.lambda B and then plasmid pBR322. The smallest active subclone, pTE12, contained a 3.1-kb insert. The insert present in one of the phages coding for E2 was also subcloned and the smallest active subclone pTE23 contained a 2-kb insert. E. coli HB101 containing plasmid pTE12 or pTE23 produced enzymes that were identical to E1 and E2, respectively, in all the properties tested.

Bacteria, Aerobic↗
PubMedDate not supplied

How multiple types of stressors impact on health.

OBJECTIVE: Although many studies have focused on the relationship between stress and health, few have examined the impact of multiple types of stressors. The current study investigated the health impact of four stressors: sexual and physical abuse history, lifetime losses and traumas, turmoil in childhood family, and recent stressful life events. METHOD: The sample included 239 female patients from a referral-based gastroenterology clinic. RESULTS: We found that the four stressors (abuse history, lifetime traumas, turmoil in childhood family, and recent stressful life events) were related to poor health status (eg, more pain, symptoms, bed disability days, physician visits, functional disability, and psychological distress); together, these stressors accounted for 32% of the variance in overall current health. Furthermore, women who scored high on one type of stressor also tended to have experienced other types. Unlike many previous studies, we did not find that social support buffered the effects of stress. CONCLUSIONS: This study provides evidence that many different types of stressors independently contribute to poor health outcome. Such findings suggest that health practitioners and researchers should question patients about histories of traumatic events, in addition to the examination of the biological aspects of illness, inasmuch as both may have notable effects on health status.

Adolescent↗
PubMedDate not supplied

Effects of coping on health outcome among women with gastrointestinal disorders.

BACKGROUND: Studies have shown that the nature and quality of coping may positively or negatively affect health outcome; however, this relationship has not been well studied among patients with gastrointestinal (GI) disorders. OBJECTIVES: The primary objective was to study the effect of different coping strategies on the health outcome of women with GI disorders and how these coping strategies may modify the effects of education, GI disease type, neuroticism, and abuse severity on health outcome. METHODS: We followed 174 patients in a referral GI clinic for 12 months to assess their health status as a derived variable of daily pain, bed disability days, psychological distress, daily dysfunction, number of visits to physicians, and number of surgeries and procedures. We obtained at baseline their GI diagnosis (functional vs. organic), neuroticism score (NEO Personality Inventory), sexual and/or physical abuse history, and scores on two coping questionnaires. Regressions analyses were used to determine the relative effect of the coping measures on health outcome and their modifying effects on education, GI disease type, neuroticism, and abuse severity. RESULTS: A higher score on the Catastrophizing scale and a lower score on the Self-Perceived Ability to Decrease Symptoms scale (Coping Strategies Questionnaire) predicted poor health outcome. Less education, a functional GI diagnosis, a higher neuroticism score, and greater abuse severity also contributed to poor health status. However, the effect of GI disease type and neuroticism on health outcome was significantly reduced by the coping measures. CONCLUSIONS: Maladaptive coping (eg, catastrophizing) and decreased self-perceived ability to decrease symptoms may adversely affect health outcome and may modify the effect of GI disease type and neuroticism on health outcome.

Adaptation, Psychological↗