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1.
褐稻虱饲料稻株中数种氨基酸的营养效应 总被引:8,自引:0,他引:8
本研究初步证实饲料稻株中甘氨酸、赖氨酸和酪氨酸含量的高低,同褐稻虱(Nilaparvata lugens Stal)的发育进度、存活率、短翅型出现率和单雌产卵量关系极为密切,它们是褐稻虱赖以正常生长发育和繁殖的重要氨基酸。 相似文献
2.
Several indexes are used to determine the iron nutritional status of plants, but their effectiveness depends either on the
plant growth conditions in natural environments or on the assay conditions. This research was conducted to test different
indexes of the iron nutritional status of a hydroponic strawberry culture where treatments mainly differed in the source of
the iron applied: Fe-EDTA, Fe-EDDHA and Fe-polyflavonoid. Macro and micronutrient concentrations in the nutrient solutions,
leaf and vascular tissues were measured. Fe concentration in the nutrient solution during the course of the experiment was
considered in relation to the stability of the different chelates. Both Fe concentration and total Fe content of leaves reflected
the effect of the treatments; Fe/Mn ratio was significant as a diagnosis index. Other element ratios as P/Fe and K/Ca are
not well related with the iron nutrition symptoms observed. Fe2+ concentration measured in leaves was not directly affected by the different chelate treatments. 相似文献
3.
Carlos García-Ferris Asuncin de los Ríos Carmen Ascaso Joaquín Moreno 《Journal of phycology》1996,32(6):953-963
Growth of Euglena gracilis Z Pringsheim under photoheterotrophic conditions in a nitrogen-deprived medium resulted in progressive loss of chloroplastic material until total bleaching of the cells occurred. Biochemical analysis and ultrastructural observation of the first stages of the starvation process demonstrated an early lag phase (from 0 to 9 h) in which cells increased in size, followed by a period of cell division, apparently supported by the mobilization of some chloroplastic proteins such as the photosynthetic CO2-fixing enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase. The degradation of the enzyme started after 9 h of starvation and was preceded by a transient concentration of this protein in pyrenoidal structures. Protein nitrogen and photosynthetic pigments as well as number of chloroplasts per cell decreased during proliferation through mere distribution among daughter cells. However, after 24 h, when cell division had almost ceased, there was a slow but steady decline of photosynthetic pigments. This was paralleled by observable ultrastructural changes including progressive loss of chloroplast structure and accumulation of paramylon granules and lipid globules in the cytoplasm. These findings reinforce the role of chloroplastic materials as a nitrogen source during starvation of E. gracilis in a carbon-rich medium. The excess of ribulose-1,5-bisphosphate carboxylase/oxygenase acts as a first reservoir that, once exhausted, is superseded by the generalized disassembly of the photosynthetic structures, if the adverse environment persists more than 24 h. 相似文献
4.
Final instar Persectania ewingii (Westwood) (Lepidoptera: Noctuidae) were fed seedling Triticum aestivum L. for 2 days to determine the approximate digestibility of the cell wall and cell content fractions. Cell wall content was estimated using a micro-analytical neutral detergent fibre technique. Approximate digestibilites of neutral detergent fibre, neutral detergent solubles and dry matter were calculated for individuals and pooled samples. P. ewingii larvae digested a small but significant proportion of the fibre ingested (13–21%), higher than that previously reported for herbivorous insects. The micro-analytical and previously used macro-analytical techniques produced similar estimates of digestibility although both techniques have inherent shortcomings, the latter requiring the pooling of samplex and the former limiting the number of replicates during chemical analysis. Differences in the amount of larval frass collected during the feeding trial (corrected for consumption) explained much of the variation in digestibility values, while there were no effects of larval mass, overall consumption and total frass produced on digestibility estimates. These results confirm that plant cell contents are the major source of nutrients to larval Lepidoptera although there is some chemical disruption of the plant cell wall. 相似文献
5.
Konrad Fiedler 《Entomologia Experimentalis et Applicata》1996,80(1):259-267
The Lycaenidae are the second-largest family of butterflies. From host-plant data collated for more than 1200 species worldwide, large-scale taxonomic, geographical and ecological patterns emerge which suggest that phytochemical similarities and barriers, coupled with phylogenetic conservatism and constraints are key factors governing hostplant use. More than two thirds of the lycaenid species are restricted to one plant family or genus. Affiliations with toxic plants are rare in the Lycaenidae, and excretion rather than sequestration of plant toxins appears to be their usual way of detoxifying host-plant compounds. Flavonoids are frequently sequestered by lycaenid larvae and are subsequently concentrated as pigments in the adults' wings, where they might play a role in visual communication. Mutualistic associations with ants occur in the larvae of more than 50% of the extant Lycaenidae species. Because of a conflict between the nutrient demands of the larvae and the proportion of plant-derived resources allocated to maintain the mutualism with ants, variation in resource quality often translates into variation of mutualistic capacities of the caterpillars, in particular under nutrient stress. 相似文献
6.
Abstract. The objectives of this study were to determine whether adult Mediterranean fruit flies, Ceratitis capitata Wiedeman (Diptera: Tephritidae), are capable of synthesizing lipids, and whether adult diet affects this ability.Lipid levels in females fed protein and carbohydrate or carbohydrate alone declined significantly from emergence to the fourth day of life and then rose back to teneral levels on the fifth day, before oviposition took place on the sixth day.In males fed protein and carbohydrate, lipid levels initially declined as males aged and then stabilized.In carbohydrate-fed males lipid levels declined following emergence and recovered somewhat by the sixth day.Lipid levels declined significantly when flies underwent post-emergence starvation, but after substantial feeding on the above-mentioned diets they eventually (within 6–7 days) reached teneral levels in all experimental groups.Multivariate analysis of variance revealed that differences in lipid contents are primarily related to the flies' age, which corresponds to the various sex-specific activities these flies exhibit.Average lipid investment in eggs was found to equal teneral lipid levels in females.Without lipogenic abilities, oviposition would completely deplete female lipid reserves.We conclude that adult medflies are capaple of lipid synthesis, and that this capability is modulated by individual and sex-specific activity patterns. 相似文献
7.
8.
Georgina L. Dasilva 《International journal of primatology》1994,15(5):655-680
A group of Colobus polykomosat Tiwai, Sierra Leone, demonstrated seasonal flexibility in its diet, with seeds, young leaves, and mature leaves each dominating
the diet at different times. Comparison of food consumption with phenological data indicates that seeds are eaten whenever
available and are preferred to other foods, while young leaves are preferred to mature leaves. Colobus polykomosalso prefer liane to tree leaves, despite the relatively high quality of mature tree foliage at the Tiwai site. Analysis of
protein, fiber, and energy values of foods selected and items available, but not eaten, suggests that preference is related
to protein and energy maximization. Leguminous plants, especially Papilionaceae and Mimosaceae, are highlighted as important
food sources for C. polykomos;seeds and leaves from these families have a high nitrogen content, and the protein content of leguminous seeds often equals
or exceeds that found in leaves. It is predicted, therefore, that colobines living in habitats with a high density of legumes
will feed heavily on seeds, subject to constraints such as seasonal availability. Where suitable leguminous species are less
common, a mixture of fruits, seeds, and young or mature leaves or both is likely to be selected. The results of this and other
recent studies of colobines do not support the notion that colobines are specialist folivores. 相似文献
9.
Improving the mineral reserves and protein quality of maize (Zea mays L.) kernels using unique genes
The effects of the maize genes, o
2 and Mal, on the concentrations of mineral nutrient cations and amino acid levels in mature maize (Zea mays L) kernels of various inbred lines were studied. Previously, the o
2 gene has been used to improve the protein quality and increase the mineral nutrient content of kernels from some inbred lines. Genotypes possessing the Mal (multiple aleurone layer) gene, contain more than one row of aleurone cells in their kernels and this gene enhances the effect of the o
2gene on improving kernel protein quality. Incorporating these genes into the maize genome increased accumulation of several mineral nutrients (including Ca, Mg, Zn, Fe, Mn, Zn and Cu) in some of the experimental lines studied. The physiological basis for this increase of mineral nutrients in the kernels is discussed. The effect of the Mal gene on the kernel amino acid composition and protein quality was also examined. Possibly, these genes could be used in combination in breeding programs to improve kernel quality and nutritional value of maize. 相似文献
10.
J. De Kok C. Van Der Schoot M. Veldhuizen H. Th. Wolterbeek 《Biological trace element research》1993,38(1):13-26
The in vitro uptake of zinc by erythrocytes was measured under near-physiological conditions, using65Zn as a radioactive tracer. Because of the presence of serum albumin—a strong zinc ligand—a low concentration of medium free
zinc was maintained. Under these conditions a high-affinity carrier for zinc transport over the cell membrane was identified.
With human erythrocytes, a Michaelis constant (K
m
) of 0.2 nM with respect to free medium zinc was measured and aV
max
of 4.5 nmoles Zn transported per h/g dry wt. TheK
m
for medium Zn increases when the size of the internal erythrocytic Zn pool is augmented, whereasV
max
remains virtually unchanged. A model to explain this phenomenon is proposed. It is suggested that this phenomenon could underlie
observations, confirmed here, that the in vitro uptake of Zn by animal erythrocytes depends on the Zn status of the animal. 相似文献