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41.
Loveness K. Nyanga Martinus J. R. Nout Eddy J. Smid Teun Boekhout Marcel H. Zwietering 《World journal of microbiology & biotechnology》2012,28(11):3239-3244
The aim of the study was to compare the effect of two low-cost, low technology traditional methods for drying starter cultures with standard lyophilisation. Lyophilised yeast cultures and yeast cultures preserved in dry rice cakes and dry plant fibre strands were examined for viable cell counts during 6?months storage at 4 and 25?°C. None of the yeast cultures showed a significant loss in viable cell count during 6?months of storage at 4?°C upon lyophilisation and preservation in dry rice cakes. During storage at 25?°C in the dark, yeast cultures preserved in dry rice cakes, and lyophilised cultures of Saccharomyces cerevisiae and Issatchenkia orientalis showed no significant loss of viable cells up to 4?months of storage. Yeast cultures preserved in dry plant fibre strands had the greatest loss of viable count during the 6?months of storage at 25?°C. Preservation of yeasts cultures in dry rice cakes provided better survival during storage at 4?°C than lyophilisation. The current study demonstrated that traditional methods can be useful and effective for starter culture preservation in small-scale, low-tech applications. 相似文献
42.
Mohamed F Ismail Doaa A Ali Augusta Fernando Mohamed E Abdraboh Rajiv L Gaur Wael M Ibrahim Madhwa HG Raj Allal Ouhtit 《International journal of biological sciences》2009,5(4):377-387
Spirulina platensis (SP) is a filamentous cyanobacterium microalgae with potent dietary phyto-antioxidant, anti-inflammatory and anti-cancerous properties. The present study aimed to investigate the chemopreventive effect of SP against rat liver toxicity and carcinogenesis induced by dibutyl nitrosamine (DBN) precursors, and further characterized its underlying mechanisms of action in HepG2 cell line. Investigation by light and electron microscopy showed that DBN treatment induced severe liver injury and histopathological abnormalities, which were prevented by SP supplementation. The incidence of liver tumors was significantly reduced from 80 to 20% by SP. Immunohistochemical results indicated that both PCNA and p53 were highly expressed in the liver of DBN-treated rats, but were significantly reduced by SP supplementation. Molecular analysis indicated that SP treatment inhibited cell proliferation, which was accompanied by increased p21 and decreased Rb expression levels at 48hrs post-treatment. In addition, SP increased Bax and decreased Bcl-2 expression, indicating induction of apoptosis by 48hrs. This is the first report of the in vivo chemopreventive effect of SP against DBN-induced rat liver cytotoxicity and carcinogenesis, suggesting its potential use in chemoprevention of cancer. 相似文献
43.
Validation of mega-environment universal and specific QTL associated with seed yield and agronomic traits in soybeans 总被引:1,自引:0,他引:1
Laura Palomeque Li-Jun Liu Wenbin Li Bradley R. Hedges Elroy R. Cober Mathew P. Smid Lewis Lukens Istvan Rajcan 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2010,120(5):997-1003
The value of quantitative trait loci (QTL) is dependant on the strength of association with the traits of interest, allelic
diversity at the QTL and the effect of the genetic background on the expression of the QTL. A number of recent studies have
identified QTL associated with traits of interest that appear to be independent of the environment but dependant on the genetic
background in which they are found. Therefore, the objective of this study was to validate universal and/or mega-environment-specific
seed yield QTL that have been previously reported in an independent recombinant inbred line (RIL) population derived from
the cross between an elite Chinese and Canadian parent. The population was evaluated at two field environments in China and
in five environments in Canada in 2005 and 2006. Of the seven markers linked to seed yield QTL reported by our group in a
previous study, four were polymorphic between the two parents. No association between seed yield and QTL was observed. The
result could imply that seed yield QTL were either not stable in this particular genetic background or harboured different
alleles than the ones in the original mapping population. QTLU Satt162 was associated with several agronomic traits of which lodging was validated. Both the non-adapted and adapted parent
contributed favourable alleles to the progeny. Therefore, plant introductions have been validated as a source of favourable
alleles that could increase the genetic variability of the soybean germplasm pool and lead to further improvements in seed
yield and other agronomic traits. 相似文献
44.
Aim: A medium with minimal requirements for the growth of Lactobacillus plantarum WCFS was developed. The composition of the minimal medium was compared to a genome-scale metabolic model of L. plantarum .
Methods and Results: By repetitive single omission experiments, two minimal media were developed: PMM5 (true minimal medium) and PMM7 [a pseudominimal medium, supporting proper biomass formation of 350 mg l−1 dry weight (DW)]. The specific growth rate of L. plantarum on PMM7 was found to be 50% and 63% lower when compared to growth on established growth media (chemically defined medium and MRS, respectively). Using a genome-scale metabolic model of L. plantarum , it was predicted that PMM5 and PMM7 would not support the growth of L. plantarum . This is because the biosynthesis of para- aminobenzoic acid ( p ABA) was predicted to be essential for growth. The discrepancy in simulated growth and experimental growth on PMM7 was further investigated for p ABA; a molecule which plays an important role in folate production. The growth performance and folate production were determined on PMM7 in the presence and absence of p ABA. It was found that a 12 000-fold reduction in folate pools exerted no influence on formation of biomass or growth rate of L. plantarum cultures when grown in the absence of p ABA.
Conclusion: Largely reduced folate production pools do not have an effect on the growth of L. plantarum , showing that L. plantarum makes folate in a large excess.
Significance and Impact of the study: These experiments illustrate the importance of combining genome-scale metabolic models with growth experiments on minimal media. 相似文献
Methods and Results: By repetitive single omission experiments, two minimal media were developed: PMM5 (true minimal medium) and PMM7 [a pseudominimal medium, supporting proper biomass formation of 350 mg l
Conclusion: Largely reduced folate production pools do not have an effect on the growth of L. plantarum , showing that L. plantarum makes folate in a large excess.
Significance and Impact of the study: These experiments illustrate the importance of combining genome-scale metabolic models with growth experiments on minimal media. 相似文献
45.
Paulo HG Mansur Lacordaire KP Cury José OB Leite Adriano A Pereira Nilson Penha-Silva Adriano O Andrade 《Biomedical engineering online》2010,9(1):29
Background
The main problem of tremor is the damage caused to the quality of the life of patients, especially those at more advanced ages. There is not a consensus yet about the origins of this disorder, but it can be examined in the correlations between the biological signs of aging and the tremor characteristics. 相似文献46.
Background
Paired mushroom bodies, an unpaired central complex, and bilaterally arranged clusters of olfactory glomeruli are among the most distinctive components of arthropod neuroarchitecture. Mushroom body neuropils, unpaired midline neuropils, and olfactory glomeruli also occur in the brains of some polychaete annelids, showing varying degrees of morphological similarity to their arthropod counterparts. Attempts to elucidate the evolutionary origin of these neuropils and to deduce an ancestral ground pattern of annelid cerebral complexity are impeded by the incomplete knowledge of annelid phylogeny and by a lack of comparative neuroanatomical data for this group. The present account aims to provide new morphological data for a broad range of annelid taxa in order to trace the occurrence and variability of higher brain centers in segmented worms.Results
Immunohistochemically stained preparations provide comparative neuroanatomical data for representatives from 22 annelid species. The most prominent neuropil structures to be encountered in the annelid brain are the paired mushroom bodies that occur in a number of polychaete taxa. Mushroom bodies can in some cases be demonstrated to be closely associated with clusters of spheroid neuropils reminiscent of arthropod olfactory glomeruli. Less distinctive subcompartments of the annelid brain are unpaired midline neuropils that bear a remote resemblance to similar components in the arthropod brain. The occurrence of higher brain centers such as mushroom bodies, olfactory glomeruli, and unpaired midline neuropils seems to be restricted to errant polychaetes.Conclusions
The implications of an assumed homology between annelid and arthropod mushroom bodies are discussed in light of the 'new animal phylogeny'. It is concluded that the apparent homology of mushroom bodies in distantly related groups has to be interpreted as a plesiomorphy, pointing towards a considerably complex neuroarchitecture inherited from the last common ancestor, Urbilateria. Within the annelid radiation, the lack of mushroom bodies in certain groups is explained by widespread secondary reductions owing to selective pressures unfavorable for the differentiation of elaborate brains. Evolutionary pathways of mushroom body neuropils in errant polychaetes remain enigmatic. 相似文献47.
Micro-array analysis of resistance for gemcitabine results in increased expression of ribonucleotide reductase subunits 总被引:5,自引:0,他引:5
Smid K Bergman AM Eijk PP Veerman G van Haperen VW van den Ijssel P Ylstra B Peters GJ 《Nucleosides, nucleotides & nucleic acids》2006,25(9-11):1001-1007
To study in detail the relation between gene expression and resistance against gemcitabine, a cell line was isolated from a tumor for which gemcitabine resistance was induced in vivo. Similar to the in vivo tumor, resistance in this cell line, C 26-G, was not related to deficiency of deoxycytidine kinase (dCK). Micro-array analysis showed increased expression of ribonucleotide reductase (RR) subunits M1 and M2 as confirmed by real time PCR analysis (28- and 2.7-fold, respectively). In cell culture, moderate cross-resistance (about 2-fold) was observed to 1-ss-D-arabinofuranosylcytosine (ara-C), 2-chloro-2'deoxyadenosine (CdA), LY231514 (ALIMTA), and cisplatin (CDDP), and pronounced cross-resistance (>23-fold) to 2',2'-difluorodeoxyuridine (dFdU) and 2',2'-difluorodeoxyguanosine (dFdG). Culture in the absence of gemcitabine reduced resistance as well as RRM1 RNA expression, demonstrating a direct relationship of RRM1 RNA expression with acquired resistance to gemcitabine. 相似文献
48.
Joseph BK Harbrow DJ Sugerman PB Smid JR Savage NW Young WG 《Apoptosis : an international journal on programmed cell death》1999,4(6):441-447
Enamel-producing cells (ameloblasts) pass through several phenotypic and functional stages during enamel formation. In the transition between secretory and maturation stages, about one quarter of the ameloblasts suddenly undergo apoptosis. We have studied this phenomenon using the continuously erupting rat incisor model. A special feature of this model is that all stages of ameloblast differentiation are presented within a single longitudinal section of the developing tooth. This permits investigation of the temporal sequence of gene and growth factor receptor expression during ameloblast differentiation and apoptosis. We describe the light and electron microscopic morphology of ameloblast apoptosis and the pattern of insulin-like growth factor-1 receptor expression by ameloblasts in the continuously erupting rat incisor model. In the developing rat incisor, ameloblast apoptosis is associated with downregulated expression of the insulin-like growth factor-1 receptor. These data are consistent with the hypothesis that ameloblasts are hard wired for apoptosis and that insulin-like growth factor-1 receptor expression is required to block the default apoptotic pathway. Possible mechanisms of insulin-like growth factor-1 inhibition of ameloblast apoptosis are presented. The rat incisor model may be useful in studies of physiological apoptosis as it presents apoptosis in a predictable pattern in adult tissues. 相似文献
49.
Anaerobic Nitrate Respiration by Erwinia carotovora subsp. atroseptica during Potato Tuber Invasion 下载免费PDF全文
The in planta induction of anaerobic nitrate respiration by Erwinia carotovora subsp. atroseptica in relation to the in situ oxygen status in soft rotting potato tubers has been investigated. In vitro experiments have shown that nitrate was required for the induction of respiratory nitrate reductase activity in E. carotovora. In addition, oxygen was found to repress this activity. Expression of respiratory nitrate reductase was found in E. carotovora cells extracted from soft rotting potato tuber tissue. However, the rate of nitrite production in these cells was approximately 70-fold lower than the rate recorded in fully induced anaerobic cultures. Oxygen measurements in soft rotting potato tubers indicated that the invading bacteria encounter the lowest oxygen concentration at the interphase between healthy and macerated tissue. Consequently, growth of bacteria present in this specific zone will be stimulated by nitrate which is present in sufficient amounts in tuber tissue. A high nitrate content of the tuber will most likely facilitate the proliferation of E. carotovora in the tuber tissue. 相似文献
50.
Holger Diedrichs Carsten Zobel Peter Theissen Michael Weber Athanassios Koulousakis Harald Schicha Robert HG Schwinger 《Trials》2005,6(1):1-7