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1.
Growth of Propionibacterium freudenreichii was studied with glycerol, lactate, and propionate as energy sources and a three-electrode poised-potential amperometric electrode system with hexacyanoferrate (III) as mediator. In batch culture experiments with glycerol and lactate as substrates, hexacyanoferrate (III) was completely reduced. Growth yields increased and the fermentation patterns were shifted towards higher acetate formation with increasing hexacyanoferrate (III) concentrations (0.25–8.0 mM). In experiments with regulated electrodes, glycerol, lactate, and propionate were oxidized to acetate and CO2, and the electrons were quantitatively transferred to the working electrode. Growth yields of 29.0, 13.4 and 14.2 g cell material per mol were calculated, respectively. The high cell yield obtained during propionate oxidation cannot be explained solely by substrate level phosphorylation indicating that additional energy was conserved via electron transport phosphorylation. Furthermore, this result indicated complete reversibility of the methyl-malonyl-CoA pathway in propionic acid bacteria.  相似文献   

2.
JAN RYSER 《Journal of Zoology》1988,216(4):673-685
Growth and maturation in a Swiss population of Rana temporaria were studied in 1983 and 1984 by means of skeletochronology. Resting line (growth ring) diameters were used to back-calculate individual body sizes in previous years; these permitted establishment of an average growth curve and determination of individual ages and sizes at first reproduction. Growth was rapid up to maturation, but continued thereafter at a decreased rate. Males were larger than females at age two but females grew faster thereafter, causing sexual dimorphism in adult body sizes. Body size distributions for both years and for frogs recaptured and first captured in 1984 were established. Growth in immatures was positively, but in adults negatively correlated with body size, with considerable variation at all sizes. Individual adult sizes were positively correlated with body sizes at the end of the first year. Average individual age at first reproduction was 2.8 years in males and 3.1 years in females (range in both sexes two to four years). There is no evidence for a two-year-cycle of reproduction.  相似文献   

3.
Journal of Plant Growth Regulation - Reactive oxygen species (ROS) are well known for their dual functions in plants. On the one hand, ROS were once thought to be harmful to plants because their...  相似文献   

4.
Synopsis Tahoe sucker, Catostomus tahoensis, were fed at three ration levels (starvation, 50% of repletion, and repletion) at three constant and cyclic temperature regimes (4–12°, 8°, 8–18°, 13°, and 13°–23°, 18° C) to examine growth rate and gross growth efficiencies. Growth rates increased with increasing temperature and ration level. Growth rates were not different between cyclic temperatures and the constant temperature equivalent to the mean of the cycle. Growth efficiencies were similar for cyclic and constant temperature regimes. Maintenance rations increased from 0.9% of the initial wet weight per day at low temperatures to 2.0 and 1.7% at intermediate and high temperatures, respectively. Assimilation efficiencies (not measured at low temperatures) did not differ between constant and cyclic temperatures. Tahoe sucker growth rates and assimilation efficiencies may not be enhanced in small streams because of this species' inability to mediate temperature cycles through behavioral thermoregulation.  相似文献   

5.
Four strains of Rhizobium japonicum, two of which produce slimy and non-slimy colony types and two others which produce large and small colony types, were isolated and cloned. All were infective and nodulated Lee soybean host plants. Each colony type was characterized as to its salt sensitivity to Na+ and K+ ions, relative level of symbiotic nitrogen fixation, and relative level of free-living nitrogen fixation. Growth studies performed in the presence of salts demonstrated that the non-slimy or small colony types were sensitive to salt with significantly depressed growth rates and cell yields. Growth rates and cell yields of slimy, large, colony types were relatively unaffected by salt. Both symbiotic and free-living (non-associative) nitrogen fixation analyses (by acetylene reduction) revealed that the non-slimy, small colonies were significantly more effective than slimy, large colonies.  相似文献   

6.
Growth rates of juvenile (1–8 g) Sacramento blackfish, an omnivorous California cyprinid which grows to >1.5 kg, were measured at three temperature ranges in laboratory aquaria where several diets were offeredad lib. and at four stocking densities in small ponds where natural food was available. Growth rates generally increased with elevations in environmental temperature. Growth in aquaria was possible with strictly plant-based diets, but was faster with pelleted diets higher in protein, lipids, and total calories. Growth rates in ponds increased with decreased stocking densities and approximated or exceeded those measured in laboratory aquaria for blackfish fed pelleted diets. The data also support the importance of energy-rich food organisms (e.g., zooplankton) in the diet of young-of-the-year blackfish in Clear Lake, California.  相似文献   

7.
Growth of sympatric populations of three important sport fish species: bluegill Lepomis macrochirus , largemouth bass Micropterus salmoides and channel catfish Ictalurus punctatus , in 14 Illinois reservoirs was assessed in an attempt to relate size-specific growth to environmental conditions. Multiple regression relationships for most species and size classes explained a large percentage of the variation in growth. Growth of small bluegill (50 mm total length, L T) showed a strong negative relationship with bluegill catch per unit effort (cpue), per cent littoral area and pH. Large bluegill (150 mm L T) growth was negatively related to Daphnia spp. and benthic macroinvertebrate abundance and lake volume, and positively related to bluegill cpue. Growth of small (100 mm L T) and large (250 mm L T) largemouth bass was not well explained by any of the measured variables. Growth of both small (300 mm L T) and large (450 mm L T) channel catfish was strongly positively related to forage fishes and ichthyoplankton abundance, and per cent littoral area while negatively related to benthic macroinvertebrates. By identifying environmental conditions associated with increased growth rates, these models provide direction for managing fish populations and suggest testable hypotheses for future study of the complex interactions between environmental conditions and growth.  相似文献   

8.
Journal of Plant Growth Regulation - Male sterility is an effective phenotype for sesame hybrid production. Cell wall invertase (CWINV) plays a crucial role in providing carbohydrates for male...  相似文献   

9.
AIMS: The aim of this study was to determine the survival and growth characteristics of Salmonella enterica in sound and chill-injured tomatoes as influenced by co-infection with proteolytic moulds. METHODS AND RESULTS: Sound (not chill injured) raw, ripe tomatoes (Lycopersicon esculentum Mill. 'Roma') were inoculated with a five-serotype mixture of S. enterica and/or Alternata alternata (two strains), Cladosporium herbarum and C. cladosporioides. Simultaneous and delayed (3 days) inoculation of tomatoes with Salmonella and each mould was studied. Growth of moulds in sound tomatoes stored at 15 and 25 degrees C for up to 10 days was accompanied by increased pH of radial pericarp tissue (pulp), which enhanced the growth of Salmonella. Growth of moulds and Salmonella at 25 degrees C was enhanced in chill-injured tomatoes compared with sound tomatoes. CONCLUSIONS: Growth of proteolytic moulds in tomatoes stored at conditions simulating those commonly used in commercial postharvest storage and handling promotes the growth of Salmonella that may be an incidental contaminant. SIGNIFICANCE AND IMPACT OF THE STUDY: Discarding tomatoes that are infected by moulds is important in handling and minimal processing practices designed to minimize the risk of human salmonellosis.  相似文献   

10.
Chen  Yunyan  Fan  Pingshan  Mo  Zhaowen  Kong  Leilei  Tian  Hua  Duan  Meiyang  Li  Lin  Wu  Liji  Wang  Zaimang  Tang  Xiangru  Pan  Shenggang 《Journal of Plant Growth Regulation》2021,40(1):379-387
Journal of Plant Growth Regulation - Deep placement of nitrogen (N) fertilizer has become one of the effective management practices for increasing crop yield and improving N recovery efficiency...  相似文献   

11.
Fibroblast Growth Factor receptor (FGFR) activity plays crucial roles in tumor growth and patient survival. However, FGF (Fibroblast Growth Factor) signaling as a target for cancer therapy has been under-investigated compared to other receptor tyrosine kinases. Here, we studied the effect of FGFR signaling inhibition on tumor growth, metastasis and lymphangiogenesis by expressing a dominant negative FGFR (FGFR-2DN) in an orthotopic mouse mammary 66c14 carcinoma model. We show that FGFR-2DN-expressing 66c14 cells proliferate in vitro slower than controls. 66c14 tumor outgrowth and lung metastatic foci are reduced in mice implanted with FGFR-2DN-expressing cells, which also exhibited better overall survival. We found 66c14 cells in the lumen of tumor lymphatic vessels and in lymph nodes. FGFR-2DN-expressing tumors exhibited a decrease in VEGFR-3 (Vascular Endothelial Growth Factor Receptor-3) or podoplanin-positive lymphatic vessels, an increase in isolated intratumoral lymphatic endothelial cells and a reduction in VEGF-C (Vascular Endothelial Growth Factor-C) mRNA expression. FGFs may act in an autocrine manner as the inhibition of FGFR signaling in tumor cells suppresses VEGF-C expression in a COX-2 (cyclooxygenase-2) or HIF1-α (hypoxia-inducible factor-1 α) independent manner. FGFs may also act in a paracrine manner on tumor lymphatics by inducing expression of pro-lymphangiogenic molecules such as VEGFR-3, integrin α9, prox1 and netrin-1. Finally, in vitro lymphangiogenesis is impeded in the presence of FGFR-2DN 66c14 cells. These data confirm that both FGF and VEGF signaling are necessary for the maintenance of vascular morphogenesis and provide evidence that targeting FGFR signaling may be an interesting approach to inhibit tumor lymphangiogenesis and metastatic spread.  相似文献   

12.
Several ocular tissues have been shown to contain growth factor activity designated under a generic name as Eye Derived Growth Factor. Purification from bovine retina was undertaken and a fraction which could induce target cells to proliferate at doses of 5 ng per ml of culture medium was obtained. Using heparin sepharose chromatography we now show that this mitogenic activity can be fractionated into three different activities. Crude extract of bovine retina used as starting material was separated into two major fractions, one with no affinity for heparin and which was named Eye Derived Growth Factor III, and one with a strong affinity for heparin and eluted from the column with 1.4 M NaCl named Eye Derived Growth Factor I. This fraction EDGF I induces cell proliferation at doses of 100 pg/ml of culture medium. A 10(5) fold purification was achieved by this single chromatography step. Cibacron Blue purified EDGF was also further fractionated by heparin sepharose. All biological activity was found to bind to heparin. One fraction eluted at 1 M NaCl named Eye Derived Growth Factor II had a biological activity at doses of 1 ng while the other growth factor was the EDGF I with biological activity at 25 pg. At this step of purification EDGF I runs as a single band on SDS polyacrylamide gel at a molecular weight of 17 000 d. These data strongly suggest that Eye Derived Growth Factors I and II are respectively similar to Brain Fibroblast Growth Factor and to Endothelial Cell Growth Factor from hypothalamus.  相似文献   

13.
Skinless precooked, uncured sausage links with and without potassium sorbate (0.1% wt/wt) were inoculated with salmonellae, Staphylococcus aureus, Clostridium perfringens, and Clostridium botulinum and held at 27 C to represent temperature abuse of the product. Total counts of uninoculated product showed that the normal spoilage flora was delayed 1 day when sorbate was present. Growth of salmonellae was markedly retarded by sorbate. Growth of S. aureus was delayed 1 day in the presence of sorbate, after which growth occurred to the same level as in product without sorbate. C. perfringens declined to below detectable levels within the first day in product with and without sorbate. Sorbate retarded the growth of C. botulinum. Botulinal toxin was detected in 4 days in product without sorbate but not until after 10 days in product with sorbate.  相似文献   

14.
Pelagic egg development in red drum, Sciaenops ocellatus, is described using tiered staging. Based on mitosis and meiosis, there are five periods: Mitosis of Oogonia, Active Meiosis I, Arrested Meiosis I, Active Meiosis II, and Arrested Meiosis II. The Periods are divided into six stages: Mitotic Division of Oogonia, Chromatin Nucleolus, Primary Growth, Secondary Growth, Oocyte Maturation and Ovulation. The Chromatin Nucleolus Stage is divided into four steps: Leptotene, Zygotene, Pachytene, and Early Diplotene. Oocytes in the last step possess one nucleolus, dispersed chromatin with forming lampbrush chromosomes and lack basophilic ooplasm. The Primary Growth Stage, characterized by basophilic ooplasm and absence of yolk in oocytes, is divided into five steps: One‐Nucleolus, Multiple Nucleoli, Perinucleolar, Oil Droplets, and Cortical Alveolar. During primary growth, the Balbiani body develops from nuage, enlarges and disperses throughout the ooplasm as both endoplasmic reticulum and Golgi develop within it. Secondary growth or vitellogenesis has three steps: Early Secondary Growth, Late Secondary Growth and Full‐Grown. The Oocyte Maturation Stage, including ooplasmic and germinal vesicle maturation, has four steps: Eccentric Germinal Vesicle, Germinal Vesicle Migration, Germinal Vesicle Breakdown and Resumption of Meiosis when complete yolk hydration occurs. The period is Arrested Meiosis II. When folliculogenesis is completed, the ovarian follicle, an oocyte and encompassing follicle cells, is surrounded by a basement membrane and developing theca, all forming a follicle complex. After ovulation, a newly defined postovulatory follicle complex remains attached to the germinal epithelium. It is composed of a basement membrane that separates the postovulatory follicle from the postovulatory theca. Arrested Meiosis I encompasses primary and secondary growth (vitellogenesis) and includes most of oocyte maturation until the resumption of meiosis (Active Meiosis II). The last stage, Ovulation, is the emergence of the oocyte from the follicle when it becomes an egg or ovum. J. Morphol. 2012. © 2012 Wiley Periodicals, Inc.  相似文献   

15.
Specziár  András  Bíró  Péter 《Hydrobiologia》2003,506(1-3):503-510
Hydrobiologia - Growth, population structure, abundance, production, and feeding of Volga pikeperch were studied in Lake Balaton. The population was mainly comprised of age-groups 0+ (59%) and 1+...  相似文献   

16.
Journal of Plant Growth Regulation - In this study, the role of hydrogen sulfide (H2S) in growth and metabolism of zucchini (Cucurbita pepo L.) was explored in a hydroponic culture system under...  相似文献   

17.
Cells stimulated with epidermal growth factor (EGF) or any one of a diverse group of other mitogenic agents display an increased tyrosine phosphorylation of a pair of 42,000 Mr proteins. Transforming Growth Factor-beta (TGF-beta) is able to potentiate the mitogenic effects of Epidermal Growth Factor on some fibroblastic cells (such as the NRK-49F cell line) and, in addition, permits the anchorage-independent growth of these cells. In this study we asked whether these growth-regulatory actions of Transforming Growth Factor-beta are associated with changes in tyrosine phosphorylation of cellular proteins, in particular the 42,000 Mr proteins. We found no effect of Transforming Growth Factor-beta on the extent or time-course of tyrosine phosphorylation, either by itself or in combination with Epidermal Growth Factor. Since the tyrosine phosphorylation of the 42,000 Mr proteins is stimulated both by receptors with tyrosine kinase activity and by diacylglycerol analogs (but not by Transforming Growth Factor-beta), we suggest that the activity of the receptor for Transforming Growth Factor-beta is linked neither to tyrosine phosphorylation nor to phosphatidyl inositol turnover.  相似文献   

18.
Journal of Plant Growth Regulation - Proline plays adaptive roles in plant tolerance to cadmium (Cd)-induced stress, but many gaps remain to be elucidated as the responses triggered by exogenously...  相似文献   

19.
Journal of Plant Growth Regulation - Manganese (Mn) deficiency in human nutrition is widespread in the rice–wheat cropping system where cereal grains are the staple food. Agronomic...  相似文献   

20.
Nerve growth factor mRNA in brain: localization by in situ hybridization   总被引:6,自引:0,他引:6  
Nerve Growth Factor is a 118 amino acid polypeptide that plays an important role in the differentiation and survival of neurons. The recent discovery that a mRNA that encodes beta Nerve Growth Factor is present in brain suggests that the Nerve Growth Factor gene may not only regulate gene expression of peripheral but also of central neurons. To identify the site(s) of Nerve Growth Factor mRNA production in the brain and to determine which cells express the Nerve Growth Factor gene, the technique of in situ hybridization was employed. A 32P-labeled RNA probe complementary to Nerve Growth Factor mRNA hybridized to cells in the stratum granulosum of the dentate gyrus and the stratum pyramidale of the hippocampus. These observations identify for the first time cellular sites of Nerve Growth Factor gene expression in the central nervous system, and suggest that Nerve Growth Factor mRNA is produced by neurons.  相似文献   

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