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61.
Biomanipulation,new perspectives for restoration of shallow,eutrophic lakes in The Netherlands 总被引:9,自引:0,他引:9
S. H. Hosper 《Aquatic Ecology》1989,23(1):5-10
Eutrophication of Dutch lakes has led to massive algal growth, disappearance of most of the macrophytes and disturbance of the food chain. The pike population has fallen sharply and bream developed very strongly, in the absence of this predator. Eutrophication problems are primarily being tackled by reducing nutrient loading. Restoration of water quality, however, seems to be impeded by the present structure of the food chain,i.e. the large bream stock. Biomanipulation, especially fish stock control with the aim of reducing the bream stock and increasing that of predatory fish, can accelerate the process of restoration. For the further development of biomanipulation it is very important that water authorities and managers of fish stocks agree on a common strategy. 相似文献
62.
童裳亮 《分子细胞生物学报》1989,(2)
鱼类的巨噬细胞和高等脊椎动物的一样,在吞灭入侵的病原体方面起着极其重要的作用。探索在体外长期培养巨噬细胞的方法,有助于研究巨噬细胞的机能。Braun-Nesje等虽已从硬头鳟(Salmo gairdneri)等鲑科鱼类的头肾中分离出大量的巨噬细胞,并在体外培养了3个月之久,但因细胞不分裂,无法传代。本研究改用组织块培养法和饲养层技术探索长期培养巨噬细胞的方法,并获得成功。迄今巨噬细胞已在体外培养22个月,传代48次。细胞的原代培养分为三组。前两组是单独的脾或头肾的组织培养;第三组是脾与头肾的混合组织培养。培养液是Leibovitz’s L-15,外加20%胎牛血清,100 IU/ml青霉素和100μg/ml链霉素。巨噬细胞的吞噬活力用酵母菌Candida 相似文献
63.
Manipulation of the opportunity to spawn was used to investigate the relationship between endocrine events, egg viability and spawning behaviour in female rainbow trout. Females were prevented from spawning by isolating them from males and gravel for up to 21 days after ovula- tion. Blood samples were taken before pairing with a male, at the onset of nesting activity, and at the completion of spawning. Plasma hormone levels of gonadotropin (GtH) and 17α,20β-dihydroxy-4-pregnen-3-one (17,2OP) were measured by specific radioimmunoassays. There were no qualitative or quantitative differences in the spawning behaviour of females paired on the day of ovulation or 7. 14, or 21 days after ovulation. There was a general decrease in the viability of eggs with increasing retention times. In females paired on the day of ovulation, or after 7 or 14 days, GtH levels increased with the onset of nesting behaviour and declined as fish reached the post-spawning condition. By day 21, GtH levels before pairing were significantly higher than prepairing levels in the other three treatment groups, and did not increase at the onset of nesting, or decrease in post-spawning fish. Plasma 17,20P remained high in prepairing and nesting samples of all four groups and declined to low levels in fish in post-spawning condition. In females paired on the day of ovulation there was a significant increase in 17,20P from the prepairing to the nesting stage. These results suggest that 17,20P plays a key role in the synchronization of behavioural and maturational events at the time of spawning. 相似文献
64.
Lean Han San Fernand Vedel Darasinh Sihachakr René Rémy 《Molecular & general genetics : MGG》1990,221(1):17-26
Summary Mesophyl protoplasts of two genotypes of cultivated tomato (Lycopersicon esculentum Mill.) and one of its wild relative species (Lycopersicon peruvianum Mill.) were fused by using electrofusion and polyethyleneglycol-induced fusion. Forty-three fertile tetraploid somatic hybrid plants, each deriving from separate calli, were recovered from both fusion procedures. Electrofusion appeared more efficient than chemical fusion for the production of somatic hybrids. These plants appeared morphologically similar, whatever the fusion procedure and tomato genotype. They had intermediate leaf, inflorescence, and flower morphology. After self-pollination, the hybrids set fruit of intermediate size and color. The hybrid nature of these plants was confirmed by isoelectric focusing of the Rubisco small subunits used as nuclear markers. L. esculentum and L. peruvianum were distinguished by means of two chloroplast markers: CF1-ATPase subunit as analyzed by isoelectro-focusing and ct DNA restriction patterns. All hybrids displayed both ct markers of only one parent with no biased transmission. Mitochondrial (mt) DNAs were prepared from flower buds by using miniaturized CsCl gradients. Preliminary analysis indicated that mt genomes from the hybrids all differed from those of both parents. mt DNA Sall restriction enzyme analysis revealed that all but two hybrids contained one novel fragment of 13.5 kb. Gene mapping experiments showed that the mt apocytochrome b and ATPase subunit 9 homologies in the somatic hybrid mt DNA resembled L. esculentum and L. peruvianum, respectively; the mt nad5 probe distinguished at least four distinct patterns in the hybrids. These results indicated that mt DNA rearrangements involving intergenomic recombinations occurred through protoplast fusion. A greater mt DNA polymorphism was induced with chemical fusion than with electrofusion. 相似文献
65.
M. Z. Oracion K. Niwa I. Shiotani 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1990,80(5):617-624
Summary Tetraploid F1 hybrids between Ipomoea batatas, sweet potato (2n = 6x = ca. 90), and diploid (2n = 2x = 30) I. trifida (H. B. K.) Don. showed various degrees of fertility reduction. The present study aimed to clarify its causes by cytological analysis of meiotic chromosome behavior in the diploid and sweet potato parents and their tetraploid hybrids. The diploid parents showed exclusively 15 bivalents, and the sweet potato parents exhibited almost perfect chromosome pairing along with predominant multivalent formation. Their hybrids (2n = 4x= 57–63) formed 2.6–5.0 quadrivalents per cell, supporting the autotetraploid nature. The meiotic aberratios of the hybrids were characterized by the formation of univalents, micronuclei, and abnormal sporads (monad, dyad, triad, and polyad). The causes underlying these aberrations were attributed in part to the multivalent formation, and in part to a disturbance in the spindle function. Three hybrids showing serious meiotic aberrations were very low in fertility. The utilization of the sweet potato-diploid I. trifida hybrids for sweet potato improvement is described and, further, the role of interploidy hybridization in the study of the sweet potato evolution is discussed. 相似文献
66.
J. M. Melzer M. A. O'Connell 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1990,79(2):193-200
Summary Two somatic hybrid plants generated from a single fusion event between Lycopersicon esculentum and irradiated L. pennellii protoplasts have been analyzed at the molecular level. Over 30 loci have been analyzed using isozymes and RFLPs. All loci tested on chromosomes 2–10 were heterozygous, while those loci on chromosome 12 were homozygous L. pennellii in both somatic hybrids. In one of the somatic hybrids, 2850, loci on chromosome 1 were also homozygous L. pennellii. The other somatic hybrid, 28F5, was heterozygous at all chromosome 1 loci tested, but exhibited altered stoichiometry of parental bands as compared to the sexual hybrid. Loci on chromosome 2 from both somatic hybrids have altered stoichiometry, with L. pennellii alleles being four times more abundant than expected. Both somatic hybrids contain the L. esculentum chloroplast genome, while only L. pennellii polymorphisms have been detected in the mitochondrial genome. 相似文献
67.
F. R. Bidinger D. S. Raju 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1990,79(4):521-524
Summary Dwarf varieties have had virtually no impact on the production of pearl millet, in contrast to the case of wheat, rice, and sorghum. This research compared tall and dwarf near-isogenic F1 hybrids to attempt to determine if there were deleterious effects of the d
2 dwarfing gene that might account for the lack of release/cultivation of dwarf pearl millet cultivars. Dwarf isohybrids on average yielded less than the tails, because of a smaller average seed size combined with a similar grain number per unit area. There was, however, a larger contribution of background genetic variation (pollinator, male-sterile, and interaction effects) to hybrid variation for nearly all characters measured, including seed size, than there was of the dwarfing gene. Selection of dwarf parents capable of producing hybrids with equal seed size and yield to that of tall parents should not be difficult.Journal article no. 1469 of the International Crops Research Institute for the Semi-Arid Tropics, Patancheru, A.P. 502 324, India 相似文献
68.
H. E. Witters S. Van Puymbroek I. Van Den Sande O. L. J. Vanderborght 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1990,160(5):563-571
Summary Elevated values of haematocrit were observed in rainbow trout (Oncorhynchus mykiss) during combined acid and aluminium exposure. Possible causes of this, i.e., decreased plasma volume, swelling of erythrocytes, and/or mobilization of erythrocytes into the blood were investigated. Slight haematocrit increases (10–20%) during mild acid stress (pH 5.0, 25 mol Ca2+·1-1) were mostly caused by osmotic shifts. Both swelling of erythrocytes rocytes and a significant decrease of the plasma volume were demonstrated in fish at pH 5.0. These osmotic disturbined were greater during acid exposure (pH 5.0) combined with Al (60 g·1-1; 200 g·1-1). In addition, numbers of erythrocytes increased by 40% compared to acid exposure, which contributed to the severe haematocrit rise (35%) during Al exposure. A contraction of the spleen releasing erythrocytes into the blood is suggested to occur as an adrenergic response to hypoxia, which is observed in fish acutely exposed to Al.Abbreviations
BV
blood volume
-
ECFV
extracellular fluid volume
-
ICFV
intracellular fluid volume
-
ISFV
interstitial fluid volume
-
MCHC
mean cell haemoglobin concentration
-
MCV
mean cell volume
-
PV
plasma volume 相似文献
69.
70.
Effect of temperature on the optimal substrate for β-oxidation 总被引:1,自引:0,他引:1
S. Egginton 《Journal of fish biology》1996,49(4):753-758
The enzyme carnitine palmitoyl tranferase (CPT) is able to use a range of fatty acids as substrates, with some variation in catalytic rate among tissue. The substrate giving maximal activity of the enzyme under optimal conditions (C16: 1) is similar in trout, salmon, goldfish, eel and tilapia. There is no evidence that thermal acclimation affects substrate preference for β-oxidation. 相似文献