The present investigation deals with purification and thermal characterization of an acid invertase produced by Fusarium solani in submerged culture. The maximum enzyme activity (9.90 U mL(-1)) was achieved after 96 h of cultivation at pH 5.0 and 30 degrees C in a basal medium containing molasses (2%) as the carbon and energy source supplemented with 1% peptone. Invertase was purified by ammonium sulfate fractionation and column chromatography on DEAE-cellulose and Sephadex G-200. The purified enzyme was proven to be homogeneous by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The molecular mass of the enzyme was 65 kDa. The optimum pH and temperature for activity were 2.6 and 50 degrees C, respectively. The Km value for sucrose was 3.57 mM with an activation energy of 4.056 kJ mol(-1). Enthalpies of activation (DeltaH) were decreased while entropies (DeltaS) of activation increased at higher temperatures. The effects of alpha-chymotrypsin and 4 M urea were tetraphasic with periodic gain and loss of enzyme activity. A possible explanation for the thermal inactivation of invertase at higher temperatures is also discussed. 相似文献
The anti-tick efficacy of combined aqueous herbal extracts of Azadirachta indica leaves, Nicotiana tabacum leaves, Calotropis procera flowers and Trachyspermum ammi seeds was evaluated using adult immersion test, larval packet test and ear bag method. The extract exhibited lethal effects on egg laying (index of egg laying=0.371404±0.00435), hatching (22.35%) and total larval mortality at 50 mg ml(-1) and reduced tick intensity on the infested calves (18 detached out of 35 at 45% (w/w) suspension, topically applied). The herbal extract exerted dose- and time-dependent response against all the developmental stages of Rhipicephalus (Boophilus) microplus considered in this study, thus justified their use in the traditional system of Pakistan. 相似文献
Variation in brown trout (Salmo trutta L.) population recruitment and structure is related to migratory patterns, which should depend on ease of access to habitats providing increased opportunity for growth. We quantified the number of young of year (YOY) as a proportion of the total number of brown trout at 24 locations on 11 streams within the Taieri catchment, New Zealand, including back calculated growth rates and emergence dates from otoliths. Locations with high absolute and relative abundance of YOY fish were related to elevation and distance from the river mainstem (habitat used by migratory fish), fish density, and the interaction between invertebrate food biomass, distance and elevation. Hatch date and growth were not related to the proportion of YOY fish, though growth was negatively correlated to total fish density. We suggest landscape features play a large role in determining recruitment and population structure. Locations at lower elevations have a high YOY density, high competition and lower growth, likely prompting out‐migration. These conditions could be created by successful return migration and spawning of large fecund fish resulting in YOY densities exceeding the habitat carrying capacity. Environmental factors, such as food availability, also played a role in determining population structure. These results provide an example of how population structure and recruitment might be controlled by local conditions and access to high growth environments in wild populations of introduced brown trout across a catchment. 相似文献
Research by the USDA-Agricultural Research Service (ARS) on biological control of weeds has been practiced for many years because of its inherent ecological and economic advantages. Today, it is further driven by ARS adherence to Presidential Executive Order 13112 (3 February 1999) on invasive species and to USDA-ARS policy toward developing technology in support of sustainable agriculture with reduced dependence on non-renewable petrochemical resources. This paper reports examples or case studies selected to demonstrate the traditional or classical approach for biological control programs using Old World arthropods against Tamarix spp, Melaleuca quinquenervia (Cav) ST Blake and Galium spurium L/G aparine L, and the augmentative approach with a native plant pathogen against Pueraria lobata Ohwi = P montana. The examples illustrated various conflicts of interest with endangered species and ecological complexities of arthropods with associated microbes such as nematodes. 相似文献
Copper was determined in the blood of breeding camels, camel calves and racing camels to evaluate copper status in these animals
in UAE. Low blood copper concentrations were reported in newly born camel calves (100%) and calves 2–4 months old (68%), breeding
camels at early (55.6%) and at mid lactation (48%) and at late pregnancy (69%). This is attributed to the low copper and high
sulfate in the Rhodes grass which is the only diet offered to the breeding camels. On the other hand only 9.7% of racing camels
showed low copper levels. This is because copper is routinely offered to racing camels when their blood copper is low. Cupric
oxide needle capsules orally administered at the rate of 8 g per adult camel was effective in elevating blood copper from
7.083 μmol/L at day zero to 10.074 μmol/L at day 28 after dosing. 相似文献
We carried out a study to see the effect of contaminated water of Nullah Dek on fine rice paddy and straw yields and trace elements accumulation in different parts of rice plants and soil. A site was selected near the bank of Nullah Dek at Kot Pindi Das in the District of Sheikhupura, Pakistan. The water of this nullah is contaminated by industrial effluents carrying different micronutrients. This water was employed to grow rice crop. Water samples were collected before transplanting and during the season with 15 days interval for analysis from 20 July to 1 November 2002 from a spot near village Shamke. Three fine rice varieties, viz. Super Basmati, Shaheen Basmati and Basmati 2000 were transplanted. These rice varieties were grown up to maturity. Paddy and straw yields data were recorded. Six composite soil samples from three random spots were collected from the experimental site before the start of the study to see the status of trace elements in soil. After the harvest of rice crop, soil, paddy and straw samples were analysed for Zn, Cu, Fe and Mn. The chemical analysis of Nullah Dek water showed that total salts concentration was greater than the safe limit, i.e. electric conductance (EC) > 1.0 dS m−1. Even sodium adsorption ratio (SAR) was very high, but there was no problem of high residual sodium carbonate (RSC). Zn, Cu, Fe and Mn were present but within safe limits. The water of Nullah Dek remained within permissible limits of irrigation from onset of rainy season till 15 October. There was an increase in EC, SAR and trace elements concentrations after 15 October but within safe limits. Soil analysis revealed its saline nature, devoid of sodicity. Among trace elements, the zinc ranged between deficiency (<0.5 mg kg−1) and adequate limits (>1.0 mg kg−1). Copper, Mn and Fe were present in adequate amounts. After the harvest of rice crop there was a slight decrease in pH, ECe and SAR at both the depths, while the concentrations of all trace elements were slightly increased with more in upper layer than the lower layer. Shaheen Basmati produced the maximum paddy yield followed by Basmati 2000 and then Super Basmati. The chemical analysis of paddy samples indicated a sufficient accumulation of zinc (1.68–1.78 mg kg−1), copper (1.38–1.45 mg kg−1), iron (6.12–6.37 mg kg−1) and manganese (2.22–2.42 mg kg−1). Analysis of rice straw also showed sufficient accumulation of zinc (27.50–28.50 mg kg−1), copper (20.0–20.50 mg kg−1), iron (270–280 mg kg−1) and manganese (2.38–2.41 mg kg−1). 相似文献
This study was performed to investigate the protective and therapeutic effects of
resveratrol (RES) against CdCl2-induced toxicity in rat testes. Seven
experimental groups of adult male rats were formulated as follows: A) controls+NS, B)
control+vehicle (saline solution of hydroxypropyl cyclodextrin), C) RES treated, D)
CdCl2+NS, E) CdCl2+vehicle, F) RES followed by CdCl2
and M) CdCl2 followed by RES. At the end of the protocol, serum levels of FSH,
LH and testosterone were measured in all groups, and testicular levels of TBARS and
superoxide dismutase (SOD) activity were measured. Epididymal semen analysis was
performed, and testicular expression of Bcl-2, p53 and Bax was assessed by RT-PCR. Also,
histopathological changes of the testes were examined microscopically. Administration of
RES before or after cadmium chloride in rats improved semen parameters including count,
motility, daily sperm production and morphology, increased serum concentrations of
gonadotropins and testosterone, decreased testicular lipid peroxidation and increased SOD
activity. RES not only attenuated cadmium chloride-induced testicular histopathology but
was also able to protect against the onset of cadmium chloride testicular toxicity.
Cadmium chloride downregulated the anti-apoptotic gene Bcl2 and upregulated the expression
of pro-apoptotic genes p53 and Bax. Resveratrol protected against and partially reversed
cadmium chloride testicular toxicity via upregulation of Bcl2 and downregulation of p53
and Bax gene expression. The antioxidant activity of RES protects against cadmium chloride
testicular toxicity and partially reverses its effect via upregulation of BCl2 and
downregulation of p53 and Bax expression. 相似文献
The purpose of this review is to provide a comprehensive comparison of spermatic cord torsion in domestic animals. Spermatic cord torsion leads to occlusion of testicular blood flow resulting in ischemia and tissue hypoxia. Spermatic cord torsion has been reported in all domestic mammals but dogs and horses are overrepresented. Abdominal pain (colic), anorexia, vomiting, lameness, and stiff gait are the most common clinical signs reported. The condition may be asymptomatic in cases of a low degree of spermatic cord torsion. In dogs, spermatic cord torsion is most commonly reported in undescended testes, which in some cases are neoplastic. However, in horses, spermatic cord torsion occurs more commonly in scrotal testes. Surgical treatment for spermatic cord torsion depends upon the degree and duration of torsion. If the affected testis is located within the scrotum and determined to still be viable, detorsion with orchidopexy can be performed. Orchiopexy of the unaffected scrotal testis is also recommended in stallions. If the affected testis cannot be salvaged, unilateral or bilateral orchidectomy is recommended. In all cases of spermatic cord torsion of an undescended testis, orchidectomy is recommended. Veterinarians should be aware of the clinical signs and treatment options for spermatic cord torsion in domestic mammals.