Genetic analysis and selection for wheat yield in drought-stressed and irrigated environments

Summary Wheat (Triticum aestivum L.) cultivars grown in the southern Great Plains of the U.S.A. are exposed to a wide range of moisture conditions due to large fluctuations in the amount and frequency of rainfall. Yield stability under those conditions is therefore a desirable trait for wheat breeders. Our primary objective was to quantify various genetic parameters for grain production in drought-stressed and irrigated environments. We also attempted to predict and measure yield responses when selection is practiced in either drought-stressed or irrigated environments, or both. Seventy F₂-derived lines from the cross, TAM W-101/Sturdy, were evaluated at Goodwell, OK, under irrigated and naturally drought-stressed conditions in 1987 and 1988. Genetic variance and heritability estimates were higher in the irrigated environment than in the drought-stressed environment. The genetic correlation coefficient for yields in the two environments was 0.20±0.16, indicating that selection of widely adapted genotypes requires testing in both environments. Based on the genetic variance/covariance structure of this particular population, the linear index which maximized the combined expected gain in both environments was 0.66Y₁ + 0.34Y₂, in which Y₁ and Y₂ are yields in the irrigated and drought-stressed environments. This index is not expected to apply across all populations; rather, it further supports the hypothesis that testing in either environment alone (drought stressed or irrigated) may not be most effective for increasing either mean productivity or yield under drought stress.     

Short communication

Papillomaviral has been identified in peripheral blood cells of both cattle and humans with and without associated disease and it has been suggested that such cells may act as sites of viral latency. In order to investigate the possibility of latent papillomaviral infection in the aetiopathogenesis of the equine sarcoid, peripheral blood derived DNA samples from 20 healthy and 34 sarcoid-affected donkeys were subject to polymerase chain reaction ( ) using papillomaviral specific primers. Analysis of blood derived samples failed to demonstrate the presence of papillomaviral in any animal. Screening of 37 matched sarcoid derived samples confirmed the presence of BPV in 34 diseased donkeys. This study supports the hypothesis of as an aetiological agent in the equine sarcoid and suggests that latent virus in circulating peripheral blood cells does not play a role in the pathogenesis and epidemiology of the equine sarcoid.     

The effect of rotation speed on the power consumption and cutting accuracy of guided circular saw: Experimental measurement and analysis of saw critical and flutter speeds

ABSTRACT

This paper investigates the effect of rotation speed and vibration response of a circular saw on the sawing process of Douglas-fir wood. An idling test was conducted on a guided circular saw to determine its stable operation speeds and vibration behavior. Short-time Fourier transform analysis was performed on saw idling test data, and variation of excited frequencies of the blade as a function of rotation speed was obtained. The saw blade critical speeds and the rotation speeds that correspond to saw flutter instability were identified. Then experimental cutting tests were conducted at different cutting conditions and the effect of rotation speed and saw vibration response on cutting power consumption and sawing accuracy was investigated. The results showed that conducting a saw idling test and vibration response analysis can identify the saw critical and flutter speeds, which is essential for identifying the optimum rotation speed of circular saw. There was a significant increase in power consumption when cutting at super-critical and super-flutter speed. The effect of rotation speed on sawing accuracy is complex and nonlinear. This effect interacts with feed speed, which makes it difficult to generalize sawing accuracy versus rotation speed in the circular sawing process.     

Control of fruit-flies (Dacus spp.) by attractants of plant origin

Four dominating species of fruit-fliesDacus zonatus, D. cucurbitae, D. dorsalis andD. ciliatus are widely distributed throughout Pakistan. They cause heavy damage to ripe and semi-ripe fruits and vegetables annually in our country. A natural attractant of plant origin, i.e., from Tulsi (Ocimum sanctum L.) was isolated and extracted in PCSIR Laboratories Complex, Karachi, with a view to applying for the control of fruit-flies. Different extracts of roots, stems, flowers, seeds, bark, and leaves were prepared in chloroform, acetone, ethylene chloride, ethanol, and ethyl acetate; and were tested for trapping fruit-flies in specially designed traps under different field conditions. A cotton pad (0.3 mg) treated with 0.25 ml of leaves extract in ethyl acetate is found to be a potent attractant for luring and trapping the fruit-flies (Dacus spp.) from a distance of 0.8 km. Methyl eugenol used as a standard attractant also gave the same results.     

Effects of Convolvulus arvensis Water Extract on Germination of Okra Under Different Seed Sizes

Convolvulus arvensis is a toxic allelopathic weed that suppresses germination and growth of crops.The prime object of present study was to investigate effect of Convolvulus arvensis water extract on germination and performance of okra with different seed sizes.The seeds of okra variety pusa green were separated into three different sizes,viz large size(4.00-5.00 mm),medium size(3.00-3.50 mm)and small size(2.00-3.50 mm),and then soaked in allelopathic plant bindweed water extract and kept in patrisdishes for germination into the germinator at 15℃.The experiment was laid out using Complete Randomized Design(CRD)with three replications.The results showed that after sowing of 12 days the highest germination was observed in non-treated seeds as compared to seeds treated in Convolvulus arvensis water extract for 1 h,further non-treated large seeds produced maximum plants as compared to treated small seeds after sowing of 24 days.Meanwhile,root length,shoot length,root fresh and dry weight,shoot fresh and dry weight were recorded higher in non-treated large seeds as compared to small seeds soaked for 1 h in Convolvulus arvensis allelopthic water extract.It could be found that Convolvulus arvensis affected germination,seed growth and overall performance of okra,further presence Convolvulus arvensis in crops could cause negative impact on germination and integrity of okra crops.     

Effect of varying dietary energy levels during the last trimester of pregnancy on subsequent first lactation performance in Sahiwal heifers

The aim of the study was to determine optimum dietary energy level during the last trimester of pregnancy for Sahiwal heifers in subtropical Pakistan. Sixteen Sahiwal heifers, 5–6 months pregnant, were assigned to four dietary treatments with four heifers on each treatment. Isonitrogenous (CP = 14.1%) diets having varying energy, namely, ME 88%, ME 100% (Control), ME 112% and ME 124% of NRC recommended level for pregnant heifers, were fed until calving. All were fed a similar diet after calving. Precalving weight gain was highest (P < 0.05) in heifers fed ME 112 and 124% (486 ± 13 and 497 ± 5 g/day, respectively) followed by ME 100% (444 ± 7 g/day), and the lowest weight gain was recorded for ME 88% (397 ± 8 g/day). A similar trend was observed for feed efficiency. Body condition score at calving in groups ME 124% and ME 112% was higher than ME 88% and ME 100%. Nutrient digestibility, birth weight of calves and milk composition except fat content were not influenced by energy levels. The highest daily milk yield was observed in heifers fed ME 100% followed by ME 112, 124, and 88%. We conclude that the NRC recommendation is applicable to the subtropical region.     

Evaluation of student attitudes to cooperative learning in undergraduate veterinary medicine

RATIONALE FOR THE STUDY: Recent studies have demonstrated that collaborative or cooperative learning (CL) provides students and teachers with a variety of advantages over traditional instructional methods. To explore the possibility of introducing CL into the veterinary undergraduate curriculum on a larger scale-to facilitate the development of professional competencies-a cooperative learning assignment (CLA) was introduced into the fourth year Bachelor of Veterinary Medicine and Surgery (BVMS) degree course at the University of Glasgow. An evaluation was carried out as a basis for optimizing subsequent CL activities in the undergraduate course. METHODOLOGY: Evaluation of student attitudes to the CLA was conducted using pre- and post-task questionnaires and a focusgroup discussion involving student representatives from several of the small groups. Quantitative questionnaire data were imported into SPSS and a statistical test was used to identify any significant shifts in student attitudes. RESULTS AND CONCLUSIONS: Analysis of the quantitative questionnaire results indicates that students-who regarded themselves generally as team players rather than competing individuals-had few concerns before or after the CLA. There were some significant shifts (negative and positive) in response to some of the questions, but generally the results were encouraging. However, a number of issues emerged from the focus-group discussion with regards to the administration of CL and matching students' expectations to their experiences. In particular, students need to be adequately informed at the outset about the CL process and about how it will be assessed, have access to the required facilities, and be comfortable with learning different skills sets from those their peers are learning. Staff facilitators require adequate guidance on what they are expected to contribute to the CL process.     

Changes in oleuropein levels during differentiation and development of floral buds in ‘Arbequina’ olives

Oleuropein is the most abundant biologically active phenolic compound in olives. It has been extensively studied for human health benefits but its role in plant development processes has received limited attention. Changes in the levels of oleuropein during early stages of flower formation and during fruit development and maturation were determined using high performance liquid chromatography. Oleuropein and other phenolic compounds were identified by comparing retention time and UV spectra with standard compounds using photodiode array detectors. Quantitative measurements were based on peak areas relative to standards. Oleuropein levels sharply decreased during the transition from vegetative to flower buds, consistent with earlier reports that higher levels of exogenously applied oleuropein inhibited flowering in Kalanchoe blossfeldiana. Oleuropein levels rapidly increased with the expansion of fertilized pistils and then sharply declined with fruit maturity. There was only a modest decline in oleuropein levels between immature and fully expanded leaves. Hesperidin, which occurs in relatively small amounts, also declined considerably during early floral buds formation. Maximum levels of verbascoside were found in fully developed green fruits while maximum levels of luteolin-7-O-glucoside and luteolin-4-O-glucoside were found in fully expanded leaves.     

Pharmacokinetics and bioavailability of doxycycline in ostriches (Struthio camelus) at two different dose rates

A bioavailability and pharmacokinetics study of doxycycline was carried out on 30 healthy ostriches after a single intravenous (IV), intramuscular (IM) and oral dose of 15 mg/kg body weight. The plasma doxycycline concentration was determined by HPLC/UV at 0 (pretreatment), 0.08, 0.25, 0.5 1, 2, 4, 6, 8, 12, 24 and 48 h after administration. The plasma concentration-time curves were examined using non-compartmental methods based on the statistical moment theory for only the higher dose. After IV administration, the elimination half-life (t_1/2β), mean residence time (MRT), volume of distribution at the steady-state (V_ss), volume of distribution (Vd_area) and total body clearance (Cl_B) were 7.67 ± 0.62 h, 6.68 ± 0.86 h, 0.86 ± 0.16 l/kg, 1.67 ± 0.52 l/kg and 2.51 ± 0.63 ml/min/kg, respectively. After IM and oral dosing, the mean peak plasma concentrations (C_max) were 1.34 ± 0.33 and 0.30 ± 0.04 µg/ml, respectively, which were achieved at a post-administration time (t_max) of 0.75 ± 0.18, 3.03 ± 0.48 h, respectively. The t_1/2β, Vd_area and Cl_B after IM administration were 25.02 ± 3.98 h, 23.99 ± 3.4 l/kg and 12.14 ± 1.71 ml/min/kg, respectively and 19.25 ± 2.53 h, 61.49 ± 7 l/kg and 40.19 ± 3.79 ml/min/kg after oral administration, respectively. The absolute bioavailability (F) of doxycycline was 5.03 and 17.52% after oral and IM administration, respectively. These results show that the dose data from other animals particularly mammals cannot be extrapolated to ostriches. Therefore, based on these results along with those reported in the literature, further studies on the pharmacokinetic/pharmacodynamic, in vitro minimum inhibitory concentration values and clinical applications of doxycycline in ostriches are required.     

Evaluation of telomerase-targeted therapies in canine cancer cell lines

Despite advances in conventional therapeutics, cancer remains an invariably fatal disease, the major challenge being to develop tumour‐specific cancer treatment strategies. Current treatments such as chemotherapy and radiotherapy rely on a crude distinction between cancer cells and normal cells. However, with an increased understanding of the molecular events in the development of cancer, it is possible that far more innovative and targeted approaches can be developed. From studies on humans and dogs, the enzyme telomerase has emerged as a central unifying mechanism underlying the immortal phenotype of cancer and has thus become a candidate for differentiating between normal and cancer cells. The level and frequency of telomerase activity and component gene expression in cancers reinforces this as a potential target for cancer therapies. This article describes two approaches to target cancer by capitalizing on the expression of this enzyme. In the first approach, we target the enzyme itself, the goal being to cause cancer cell death. In the second approach, we utilize the respective gene promoters for telomerase component enzymes to drive expression of a reporter gene in cancer cell lines. The results demonstrated that targeted gene expression using promoter elements can be achieved specifically in telomerase‐positive cell lines. However, targeting the enzyme itself proved less successful and warrants investigations into alternative approaches.