家蚕个体发育中酯酶同工酶的研究(英文)

研究了PM，Dz和KA三个家蚕品种个体发育中α-酯酶和β-酯酶同工酶的电泳图谱类型。综合酶谱揭示了三个品种的α-酯酶同工酶出现在16、21、19区带。三个种在个体发育中的卜酯酶出现在15、19、15区带。一些同工酶在发育阶段出现、消失、再出现。而幼虫期酯酶的异源性最大。     

Pinpointing the source of a lunar meteorite: implications for the evolution of the Moon

The lunar meteorite Sayh al Uhaymir 169 consists of an impact melt breccia extremely enriched with potassium, rare earth elements, and phosphorus [thorium, 32.7 parts per million (ppm); uranium, 8.6 ppm; potassium oxide, 0.54 weight percent], and adherent regolith. The isotope systematics of the meteorite record four lunar impact events at 3909 +/- 13 million years ago (Ma), approximately 2800 Ma, approximately 200 Ma, and <0.34 Ma, and collision with Earth sometime after 9.7 +/- 1.3 thousand years ago. With these data, we can link the impact-melt breccia to Imbrium and pinpoint the source region of the meteorite to the Lalande impact crater.     

Reaction of chlorpyrifos-methyl in aqueous hydrogen sulfide/bisulfide solutions

The kinetics of the reactions of chlorpyrifos-methyl, an organophosphorus insecticide, with hydrogen sulfide (H(2)S) and bisulfide (HS(-)) were determined in well-defined aqueous solutions. The resulting pseudo-first-order rate constant for chlorpyrifos-methyl with bisulfide yielded a second-order rate constant of (2.1 +/- 0.3) x 10(-3) M(-1) s(-1). The second-order rate constant for chlorpyrifos-methyl with hydrogen sulfide is significantly slower than the second-order rate constant with bisulfide. The contribution of H(2)S to the observed degradation rate constant of chlorpyrifos-methyl at concentrations of up to 4 mM H(2)S is not significant. The second-order rate constant of chlorpyrifos-methyl with H(2)S was too low to be measured in this study. The results indicate that HS(-) present at environmentally relevant concentrations may represent an important sink for phosphorothionate triesters in a coastal marine environment, while H(2)S reacts too slowly to be environmentally relevant (pH 6-9). Trichloropyridinol, the major product of hydrolysis of chlorpyrifos-methyl, is only a minor product of the reaction of chlorpyrifos-methyl with bisulfide; however, trichloropyridinol was found to be stable under the experimental conditions.     

Continuous extradural analgesia in a cow with complex regional pain syndrome

A chronic pain syndrome, similar to the complex regional pain syndrome (CRPS) described in human beings, was diagnosed in a cow with persisting severe pelvic limb lameness. Diagnosis was based on the disproportionate relationship between the severity and duration of pain and the lesion, the failure of conventional analgesic and surgical therapy and the presence of characteristic clinical features. Multimodal therapy, i.e. a mixture of methadone, ketamine and bupivacaine was administered continuously for 17 days via an extradural catheter to counteract nociceptive hypersensitization. Doses were adjusted daily after assessing the effect, using a composite pain score. Physiotherapy was also performed. The diagnosis of CRPS in cattle is unusual. In this case, treatment was successful and the cow was discharged mildly lame and in improving physical condition. Long-term extradural analgesia proved to be safe and effective in the treatment of this syndrome, which was nonresponsive to conventional therapy.     

Evaluation of administration of isoflurane at approximately the minimum alveolar concentration on depression of a nociceptive withdrawal reflex evoked by transcutaneous electrical stimulation in ponies

OBJECTIVE: To investigate effects of isoflurane at approximately the minimum alveolar concentration (MAC) on the nociceptive withdrawal reflex (NWR) of the forelimb of ponies as a method for quantifying anesthetic potency. ANIMALS: 7 healthy adult Shetland ponies. PROCEDURE: Individual MAC (iMAC) for isoflurane was determined for each pony. Then, effects of isoflurane administered at 0.85, 0.95, and 1.05 iMAC on the NWR were assessed. At each concentration, the NWR threshold was defined electromyographically for the common digital extensor and deltoid muscles by stimulating the digital nerve; additional electrical stimulations (3, 5, 10, 20, 30, and 40 mA) were delivered, and the evoked activity was recorded and analyzed. After the end of anesthesia, the NWR threshold was assessed in standing ponies. RESULTS: Mean +/- SD MAC of isoflurane was 1.0 +/- 0.2%. The NWR thresholds for both muscles increased significantly in a concentration-dependent manner during anesthesia, whereas they decreased in awake ponies. Significantly higher thresholds were found for the deltoid muscle, compared with thresholds for the common digital extensor muscle, in anesthetized ponies. At each iMAC tested, amplitudes of the reflex responses from both muscles increased as stimulus intensities increased from 3 to 40 mA. A concentration-dependent depression of evoked reflexes with reduction in slopes of the stimulus-response functions was detected. CONCLUSIONS AND CLINICAL RELEVANCE: Anesthetic-induced changes in sensory-motor processing in ponies anesthetized with isoflurane at concentrations of approximately 1.0 MAC can be detected by assessment of NWR. This method will permit comparison of effects of inhaled anesthetics or anesthetic combinations on spinal processing in equids.     

Effect of management on reproductive performances of the Achai cattle in the Hindu Kush (Northern Pakistan)

This study evaluates the effect of management on the undocumented Achai cattle reproductive performance in transhumant farming systems (TFS) and in sedentary farming systems (SFS) in northwestern Pakistan. Data were collected from 172 households in TFS and 270 households in SFS to analyze the effect of farming systems, parity, and calving season on key reproductive traits. The results show that farming systems significantly affect pubertal age, while parity has no significant effect on any of the key traits. The calving season significantly affects the postpartum anoestrus interval in TFS only. More than 50% of the cows in both systems have postpartum anoestrus intervals and calving intervals within the recommended values for cows in tropical countries. Achai cows have high first-service conception rates (70% and 71% for TFS and SFS, respectively) and require a relatively small number of services per conception (1.53 ± 0.06 and 1.48 ± 0.05 SE for TFS and SFS, respectively). This local breed thus warrants conservation under both farming systems.     

Nitrogen status and biomass determination of oilseed rape by laser-induced chlorophyll fluorescence

Site-uniform nitrogen fertilization can lead to local over- or under-supply of nitrogen on heterogeneous sites. Suitable sensor solutions are needed to perform on-the-fly measurements of the local N-requirement. Sensor systems already in use to this end in agricultural practice are based on light reflectance measurements.By contrast, a measurement principle based on laser-induced two-wavelength chlorophyll fluorescence (LICF) presents some major advantages given that the measurement signals originate only from plant material. The LICF measurement principle measures the chlorophyll fluorescence induced by red laser light at 630 nm at wavelengths of 690 nm and 730 nm. The ratio of the two wavelengths correlates strongly with aboveground N content, with statistical analysis of measurement data providing biomass information. Thus, both N content and biomass can be determined simultaneously using this technology.This work tested the accuracy of this measurement principle in determining N content and biomass of oilseed rape in field trials. LICF measurements were compared to reflectance-based measurements, both of which were referenced against conventionally determined values for N content and biomass dry weight.Our results show that the N status and aerial biomass dry weight determination by LICF measurements are possible with the same accuracy as with the conventional determination. Furthermore, it could be shown that the LICF measurement allows for the determination of biomass independent of the N content. The good performance of LICF-based protocols in determining local N content and biomass supports their potential utility in site-specific fertilizer application.     

Adaptation of ecotypes and cultivars of subterranean clover (<Emphasis Type="Italic">Trifolium subterraneum</Emphasis> L.) to German environmental conditions and its suitability as living mulch

Abstract A total of 320 accessions of subterranean clover (Trifolium subterranenum L.) were screened for adaptation to the environmental conditions in southern Germany, as well as their suitability as cover crops or living mulches. The accessions, derived from collections of the Department of Agriculture and Food Western Australia and the International Research Center for Agriculture in Dry Areas, were propagated in the greenhouse and grown in rows. Selected accessions were then tested in plots and as an intercrop in wheat, in order to test their suitability as living mulch. Moreover, a frost resistance screening was carried out in a climate chamber. Adaptation to southern German conditions and frost tolerance was generally better than expected, as most accessions survived winters with snow cover and transitory temperatures as low as \(-\,10\,^\circ \)C. Accessions with particularly high frost tolerance were identified and several accessions persisted over four generations of self-reseeding. Although there was a large range of morphological characteristics, no differences concerning their suitability as living mulch could be observed. The results suggest that subterranean clover is sufficiently winter hardy to be grown as an overwintering cover crop or living mulch in southern Germany. Commercially available cultivars appear suitable in the first instance, even though these have not been selected for cold winters. However, adaptation might be further improved by targeted selection among accessions.     

Influence of ambient light and temperature on laser-induced chlorophyll fluorescence measurements

Chlorophyll fluorescence analysis is a powerful tool for the study of spatial and temporal heterogeneities of photosynthetic performance and has been successfully used at the laboratory scale. Field applications, however, are confronted with the challenges presented by fluctuating environmental factors, particularly varying light and temperature conditions.The influence of ambient light and temperature on the measurement signal of the laser-induced two-wavelength chlorophyll fluorescence remains both controversially and largely not well understood. Yet, a thorough understanding of this issue is essential for exploiting the large potential of this measurement method for precision agriculture as well as for precision phenotyping in plant breeding where the influence of ambient light and temperature is inevitably present. To fill this gap in our knowledge, we therefore investigated this area under both field and controlled laboratory conditions.Field measurements of laser-induced two-wavelength chlorophyll fluorescence under variable light conditions show a linear influence of direct sunlight on the ratio of F₆₉₀/F₇₃₀, whereas the ratio is unchanged under diffuse sunlight.We describe these measurement results in terms of a physical model of light–matter interaction in plant leaves. In particular, the results appear to derive from energetic saturation effects of the upper plant layers induced by sunlight, which result in larger mean depths of fluorescence emission induced by additional exciting light (i.e. laser light), in connection with the different scattering properties of the two different fluorescence light wavelengths (690 nm and 730 nm) on their way to the surface. The same model also provides an explanation for the temperature dependence of the fluorescence intensity ratio and is well suited to deal with the effects of both variable light and temperature conditions under field conditions.