Presentation and first applications of a dynamic population model for brown trout, Salmo trutta L.: aid to river management

A mathematical model representing the long-term change in a trout population under different river management scenarios is presented. It describes the structure of a population broken down into age classes based on the Leslie matrix; if the population structure for any given month is known, the model should be able to estimate that of the following month. The passage from one month to the next takes into account various relevant factors: survival rate of individuals in the different age classes; fertility rate of females; linear and weighted growth rates; displacement linked to habitat fluctuations using weighted usable area (WUA) values. The model was applied to two French rivers. Regular monitoring of trout populations on the River Kernec enabled comparison of the response of the model with no displacement, with actual variations in fish stocks on the first river. In addition, the knowledge of WUA chronologies on the River Echez made it possible to carry out initial simulations of the response of a fish population to different river management scenarios at the second site.     

兰州市生态农业旅游开发

系统分析了兰州市发展生态农业旅游的有利条件、开发现状和存在问题,提出了发展兰州市生态农业旅游的建议。     

Repeated grading of weed abundance and multivariate methods to improve the efficacy of on-farm weed control trials

We evaluated whether new information could be drawn from additional data collection and unconventional statistical analyses of an on-farm trial. First, we compared a conventional sampling method using a biomass estimate of weed abundance to repeated visual assessment of the percentage ground cover of weeds. The biomass was sampled once after the treatment, whereas the ground cover was repeatedly sampled once before weed control plus several occasions after weed control. Second, we contrasted the outcomes from analysis of variance ( anova ), taking samples from a single point in time with repeated measures (rm) anova and a multivariate method. As the outcomes and conclusions drawn were relatively similar, we conclude that the ground cover estimate of weed abundance was as reliable as the biomass estimate. The rm anova enabled us to follow the temporal trend in response to treatments in the most abundant species, including possible initial differences. Multivariate analysis went even further, by clearly displaying species-wise responses and treatment selectivity.     

Investigation of threatened arable weeds and their conservation status in Turkey

Agronomic operations carried out in arable lands may cause changes in weed populations and also decrease the number of animal species that depend on these weed species. An emerging paradigm is the conservation and sustainability of weed species. In this study, risk status of arable weeds in Turkey was evaluated and it was determined that 112 of them (76 endemic and 36 non-endemic species) were at risk according to the IUCN Red List. Turkey is extremely diverse, with over 3000 endemic plant species out of nearly 12 000 recorded. Considering endemic weeds, they are classified in the following risk categories: critically endangered (four weed species), endangered (EN) (six), vulnerable (VU) (14), near threatened (seven), least concern (41) and data deficient (DD) (four species). Among the non-endemic weeds, three species are EN, 31 VU and two are DD. The families with the highest threatened weed species are Scrophulariaceae, Fabaceae, Asteraceae, Brassicaceae and Lamiaceae. The identification of weed species in arable habitats and their risk status is a useful tool for assessing and monitoring how the sustainability of weed populations is affected by farming practices. The results show the necessity of adopting new environment-friendly agricultural methods to conserve the high number of endemic weed species under threat in Turkey.     

Genetic basis of pectoral fin deformities in the African catfish Clarias gariepinus (Burchell, 1822), Heterobranchus longifilis (Valenciennes 1840) and their hybrids

Morphological aberrations of the pectoral fins in nine mating combinations involving Clarias gariepinus (Burchell, 1822), Heterobranchus longifilis (Valenciennes, 1840) and their hybrids were investigated to determine the level and genetic basis of occurrence. The highest mean percentage survival in a Clarias× Clarias group was 75%, whereas the least mean percentage survival was 2% in the same group. The least mean percentage survival (40.3%) in the remaining three groups occurred in the cross of female hybrid (right pectoral fin absent) × male C. gariepinus (right pectoral fin absent). A maximum of nine types of aberrations was observed in the four mating groups – double dorsal fin, curved posterior dorsal fin, spineless right pectoral fin, right pectoral fin absent, left pectoral fin absent, rudimentary pectoral fin, both pectoral fins absent, double anal fin and curved anterior dorsal fin. These nine aberration types were recorded in the Clarias× Clarias group, with a total frequency ranging from 7.14% to 75.00%. The least number of aberrations was observed in the hybrid ×Clarias group (double dorsal fin and both pectoral fins absent) with a frequency range of 1.47–5.55%. No aberration was observed in two crosses involving female hybrid (right or left pectoral fin absent) × female C. gariepinus (normal). The level of aberrations in some of these crosses indicates the involvement of genotype rather than the influence of environment.     

Characterization of a calcium-soluble protein fraction from yellow mustard (Sinapis alba) seed meal with potential application as an additive to calcium-rich drinks

A calcium-soluble protein isolate (CSPI) was prepared from the supernatant obtained after addition of 0.75 M calcium chloride to a pH 5.0 aqueous extract of yellow mustard (Sinapis alba) seed meal. Total amino acid analysis showed that the CSPI has significantly higher (p < 0.05) contents of glutamic acid + glutamine, cysteine, and proline when compared to the precipitated, calcium-insoluble proteins. Peptide mass fingerprinting of tryptic peptides of the major polypeptides by mass spectrometry indicated that the CSPI is composed mainly of cruciferin proteins with a contribution from napins (the major allergenic proteins of S. alba). The S. alba CSPI had significantly higher (p < 0.05) protein solubility and emulsion formation ability in the presence of 0.75 M calcium chloride when compared to similar isolates prepared from Brassica juncea (brown mustard) and soybean seed meals. We suggest that the S. alba CSPI could be used to prepare calcium-fortified high protein liquid products. However, the presence of allergenic proteins in this extract may limit its widespread food use.     

Blood pressure lowering effect of a pea protein hydrolysate in hypertensive rats and humans

The blood pressure lowering effect of a pea protein hydrolysate (PPH) that contained <3 kDa peptides, isolated by membrane ultrafiltration from the thermolysin digest of pea protein isolate (PPI), was examined using different rat models of hypertension as well as hypertensive human subjects. The PPH showed weak in vitro activities against renin and angiotensin converting enzyme (ACE) with inhibitory activities of 17 and 19%, respectively, at 1 mg/mL test concentration. Oral administration of the PPH to spontaneously hypertensive rats (SHR) at doses of 100 and 200 mg/kg body weight led to a lowering of hourly systolic blood pressure (SBP), with a maximum reduction of 19 mmHg at 4 h. In contrast, orally administered unhydrolyzed PPI had no blood pressure reducing effect in SHR, suggesting that thermolysin hydrolysis may have been responsible for releasing bioactive peptides from the native protein. Oral administration of the PPH to the Han:SPRD-cy rat (a model of chronic kidney disease) over an 8-week period led to 29 and 25 mmHg reductions in SBP and diastolic blood pressure, respectively. The PPH-fed rats had lower plasma levels of angiotensin II, the major vasopressor involved in development of hypertension, but there was no effect on plasma activity or renal mRNA levels of ACE. However, renal expression of renin mRNA levels was reduced by approximately 50% in the PPH-fed rats, suggesting that reduced renin may be responsible for the reduced levels of angiotensin II. In a 3-week randomized double blind placebo-controlled crossover human intervention trial (7 volunteers), significant (p<0.05) reductions (over placebo) in SBP of 5 and 6 mmHg were obtained in the second and third weeks, respectively, for the PPH group. Therefore, thermolysin derived bioactive peptides from PPH reduced blood pressure in hypertensive rats and human subjects, likely via effects on the renal angiotensin system.     

马家塔露天矿生态复垦区土壤养分状况研究

本文系统研究了神东矿区马家塔露天采坑复垦区土壤养分状况,结果显示:复垦区土壤基本上为原始回填土,剖面层次不发育,成土程度很低;土壤机械组成以砾石、粗沙为主,含量高达90%。有机质、含碱解氮含量略高于未受扰动的原状土壤,但速磷、速钾含量均低于原状土壤,总体评价土壤属于养分贫乏型;成土程度低、养分含量少是农林业生产水平不高的主要原因。研究表明通过改良复垦工艺以及提高复垦区生产管理水平是提高土地生产力的主要措施。     

乳酸菌添加剂对青藏高原燕麦青贮品质的影响

[目的]研究乳酸菌添加剂对青贮燕麦发酵品质的影响,为燕麦的青贮提供技术条件。[方法]按0．005g／kg燕麦的添加量,将乳酸菌粉剂直接加入燕麦,采用捆裹青贮系统进行青贮。处理80d后,观察其感官特征并测定品质,与普通青贮燕麦和青刈燕麦进行比较。[结果]乳酸菌青贮燕麦的气味、色泽和手感均优于普通青贮燕麦,其pH值低于3．8,乳酸与乙酸的比值下降,乳酸占总酸的比例增加,DM、CP和Ash含量增加,NDF、ADF含量降低。[结论]乳酸菌添加剂改善了青贮燕麦的品质,所得燕麦属于优质青贮料。