Substrate concentration affects the in vitro metabolism of 17-hydroxyprogesterone by ovaries of the carp,Cyprinus carpio

Carp ovarian tissue was incubated with ³H-17-hydroxyprogesterone in the presence of 0, 0.1, 1, 10, and 100 μg ml⁻¹ unlabeled 17-hydroxyprogesterone. The pattern of metabolites formed showed a marked variation with substrate concentration. Formation of glucuronide and sulphate conjugates was important only at low substrate concentration. At high substrate concentration (10 and 100 μg ml⁻¹) 17,20α-dihydroxy-4-pregnen-3-one was the major metabolite, but at intermediate concentrations polar 7α-hydroxypregnanetetrols predominated. The results support the hypothesis that at low substrate concentrations conjugating, 5α-reducing and 7α-hydroxylating enzymes, of high activity but low capacity, act as scavengers to deactivate any steroids formed during the relatively low pituitary gonadotrophin secretions which are necessary for oocyte development, but that during the prespawning gonadotrophin surge when high levels of substrate are present these enzymes are saturated and 17,20α-dihydroxy-4-pregnen-3-one (17,20αP) becomes the major ovarian steroid. The possible role of 17,20αP during oocyte final maturation requires further examination.     

Effect of γ (Gamma)-radiation on the physico-mechanical properties of grafted jute fabric reinforced polypropylene (PP) composites

The bleached jute fabric (BJF) reinforced polypropylene (PP) composites with various contents of acrylic acid (AA)-treated BJF and un-AA-treated BJF were fabricated by compression moulding method at 190 °C. The AA-grafted BJF reinforced PP composites were then irradiated by γ-ray at various doses. The mechanical properties of neat PP (N-P), ungrafted-BJF and PP composites (UG-BJFPC), AA-grafted-BJF and PP composites (AA-BJFPC) and γ-ray cum AA-grafted-BJF and PP composites (γAA-BJFPC) show maximum tensile strength (TS) of 30, 46, 47 and 51 MPa, maximum flexural strength (FS) of 34, 49, 50 and 54 MPa and maximum Young’s modulus (E) of 280, 428, 436, and 680 MPa, respectively. The increase of TS, FS and E from UG-BJFPC are 2 %, 2 %, and 2 % for AA-BJFPC and 11 %, 10 % and 59 % for γAA-BJFPC. The TS, FS and E are found to increase with radiation dose up to 500Krad and then decrease. The water absorption (WA) for UG-BJFPC, AA-BJFPC and γAA-BJFPC is respectively about 14, 10 and 9 %, indicating a gradual development of hydrophobic character of the composites first by AA-treatment and then by γ-ray-treatment. AA treatment on jute fabric and gamma irradiation on composite result in significant change of morphology of the jute fabric composites surface and better mechanical bonding between fabric and polymer matrix, as a result improved mechanical properties are found.     

Comparison of steady- and unsteady-state drainage equations for determination of subsurface drain spacing in paddy fields: a case study in Northern Iran

In Northern Iran paddy fields, waterlogging is a serious problem. Provision of subsurface drainage seems to be a prerequisite for optimal crop production. Considering specific characteristics of the paddies, application of a suitable equation for planning of subsurface drainage systems is of great importance. In this study, five steady-state equations including Hooghoudt, Kirkham, Dagan, Ernst, and Ernst–Hooghoudt; and three unsteady-state equations including Glover–Dumm, Van-Shilfgard, and De-zeeuw–Hellinga were implemented to compute drain spacing. Required field data were obtained from 52 ha of paddy fields of “Haraz Human-Agriculture Resources Development Center,” located in Mazandaran province of Iran. The computed drain spacings were evaluated using dynamic equilibrium concept and DRAINMOD model. The minimum and maximum drain spacings were found to be 26 and 63 m corresponding to Glover–Dumm and Ernst equations, respectively. Based on the dynamic equilibrium concept, the averages of the computed water table depths for the drain spacings obtained by the unsteady-state equations were 0.5–0.63 m as compared with those obtained by the steady-state methods which were in the range of 0–0.43 m. According to the DRAINMOD model simulations, the maximum relative yield was 80.2 % which was obtained when the drain spacing was 26 m and it reduced to 73.5 % when the drain spacing was increased to 63 m. The computed drain spacings suggested by the unsteady-state equations were found to be more suitable than those obtained from the steady-state equations for the study area.     

Effects of carbohydrate source and polyethylene glycol on maturation and germination of somatic embryos in walnut (<Emphasis Type="Italic">Juglans regia</Emphasis> L.)

Low efficiency of somatic embryo maturation, germination, and conversion to plantlets is a major problem in many species including J. regia L. Germination efficiency of somatic embryos is very low in walnut. In this study, effects of two carbohydrate sources, sucrose and maltose (each at 3% and 6%), and two kinds of PEG (4000 and 6000) (each at four levels of 1.5%, 3%, 5% and 7.5%) on maturation and germination of walnut embryos were tested. The number of somatic embryos increased conspicuously on medium containing PEG. Furthermore, higher levels of PEG-4000 (7.5%) could remarkably enhance the morphogenesis of somatic embryos and the number of embryos produced. PEG-4000 stimulated somatic embryo maturation of walnut. This stimulatory effect was dependent on the carbohydrate source used. Sucrose in combination with PEG-4000 produced 50% of cotyledonary and normal somatic embryos. Different concentrations of PEG were effective on the number of embryos with a shoot meristem. PEG-4000 7.5% and sucrose 3.0% produced the highest rate (50.0%) of normal shooting embryos. However, PEG (4000, 6000) and maltose caused an unfavorable effect and increased the frequency of abnormal shaped somatic embryos.     

高粗料日粮中添加脂肪对奶年血液代谢产物瘤胃发酵和干物质消化率影响的研究

对50头泌乳中期的奶牛进行为期6周的饲养试验，研究高粗料高脂肪日粮对奶牛血液代谢产物、瘤胃发酵和干物质消化率的影响。试验设有10个重复，每个重复5头奶牛，每头奶牛给定一种日粮。试验用日粮为：对照日粮（日粮1）和试验日粮（高粗料75％高脂肪7．5％，日粮2；高粗料，中等水平脂肪5．0％，日粮3；中等水平粗料65％，高水平脂肪，日粮4；中等水平粗料和脂肪，日粮5；或者对照日粮中含有50％粗料和2．0％脂肪）。这些日粮含氮量相同（CP17．7％）。粗饲料由20苜蓿干草、40％苜蓿半干青贮和40％青贮玉米组成。所用脂肪由80％瘤胃 保护脂肪和20％黄色油脂组成。试验结果表明：试验组和对照组的血糖浓度差异不显著；试验组的血浆非酯化脂肪酸（NEFA）高于对照组。而奶牛采食日粮的粗饲料和脂肪水平不同，其NEFA差异不显著；对照组、试验组与粗饲料和脂肪水平不同的日粮的瘤胃PH、瘤胃VFA浓度和干物质消化率差异不显著。     

Sexual behaviour of yearling Awassi,Charollais × Awassi and Romanov × Awassi rams exposed to oestrousAwassi ewes

This study was conducted to evaluate the sexual performance of 10-month-old, ram lambs of different breed groups. Eight ram lambs each of Awassi (A), F₁ Charollais × Awassi (CA) and F₁ Romanov × Awassi (RA) breed types were subjected to sexual performance tests by being individually exposed to two oestrous Awassi ewe lambs for four 20-min periods. Bouts of leg kicking and anogenital sniffing were similar among breed groups. Mounting frequency was greater (p < 0.05) in RA than in A and CA ram lambs. Tail-raising was greater (p < 0.05) and mating rate tended to be greater (p < 0.10) in A than in RA and CA ram lambs. The number of mounts per tail-raising (efficiency) was influenced by breed group and test day (p < 0.05). Awassi ram lambs maintained the best efficiency throughout the experiment. Efficiency in RA and CA ram lambs improved with each test day. Results of the present study indicate that RA ram lambs have greater mounting frequency than A and CA, while Awassi are more capable of mating with fat-tailed females than the CA and RA ram lambs.     

Triploid and Hexaploid Regenerants from Hexaploid Timothy (Phleum pratense L.) via Anther Culture

Pollen embryos were obtained from eight genotypes and viable green plants were regenerated from four genotypes in an anther-culture experiment with 165 genotypes of Phleum pratense L. Formation of proembryos inside the cultured anthers during the first 10—12 days was significantly influenced by genotypes and by the type of nutrient media. Primary embryos developed into multiple secondary embryos before regeneration of plants. Among a total of 62 plants regenerated, only 13 were albinos. Of the green regenerants, 11 were triploid while 35 were hexaploid when DNA-content was measured by flow cytometry. Eight plants with a triploid DNA-content did possess the triploid chromosome number of 21. Triploid and hexaploid regenerants from two different parents showed simplified isozyme (GPI and PGD) banding patterns relative to that of their parents.     

Screening sorghum genotypes for salinity tolerant biomass production

Genetic improvement of salt tolerance is of high importance due to the extent and the constant increase in salt affected areas. Sorghum [Sorghum bicolor (L.) Moench] has been considered relatively more salt tolerant than maize and has the potential as a grain and fodder crop for salt affected areas. One hundred sorghum genotypes were screened for salinity tolerance in pots containing Alfisol and initially irrigated with a 250-mM NaCl solution in a randomized block design with three replications. Subsequently 46 selected genotypes were assessed in a second trial to confirm their responses to salinity. Substantial variation in shoot biomass ratio was identified among the genotypes. The performance of genotypes was consistent across experiments. Seven salinity tolerant and ten salinity sensitive genotypes are reported. Relative shoot lengths of seedlings were genetically correlated to the shoot biomass ratios at all stages of sampling though the relationships were not close enough to use the trait as a selection criterion. In general, the whole-plant tolerance to salinity resulted in reduced shoot Na⁺ concentration. The K⁺/Na⁺ and Ca²⁺/Na⁺ ratios were also positively related to tolerance but with a lesser r ². Therefore, it is concluded that genotypic diversity exists for salt tolerance biomass production and that Na⁺ exclusion from the shoot may be a major mechanism involved in that tolerance.     

Molecular simulations of Taxawallin I inside classical taxol binding site of β-tubulin

A new taxoid Taxawallin I (1) along with two known taxoids (2-3) were isolated from methanolic bark extract of Taxus wallichiana Zucc. Structural characterization was confirmed by mass and NMR spectral techniques. Taxawallin I exhibited significant in-vitro anticancer activity against HepG2, A498, NCI-H226 and MDR 2780AD cancer lines. Tubulin binding assay was performed to assess its tubulin binding activity. Molecular docking analysis was performed to study the potential binding mode inside the taxol binding site of β-tubulin.     

Microbial and enzyme activity in soils amended with a natural source of easily available carbon

The addition of sugar beet to soils as a source of C led to an increase in the availability of easily utilizable C (glucose), which in turn markedly increased numbers of soil bacteria and of the yeast Williopsis californica. Nitrification, P solubilization, urea hydrolysis (and the subsequent nitrification of liberated NH _inf4 ^sup+ ) were stimulated by this amendment. The stimulation of nitrification may have been a result of increased heterotrophic nitrification. In contrast, the concentration of sulphate in S^o-amended soils declined following amendment, presumably as the result of enhanced S immobilization. Activity of the enzymes amylase, aryl sulphatase, invertase, phosphatase, dehydrogenase, and urease were all stimulated by the sugar beet amendment. These results suggest that sugar beet amendment could be used to increase the rate of release of plant-available ions from fertilizers such as insoluble phosphates. Problems may arise, however, from a subsequent increase in nitrification and reduced sulphate availability.