Chlorophyll mutations after low doses of chronic irradiation of barley

The chlorophyll mutation rate on a large number of plants after the dose rates 0·004–16·800 R/day during the whole vegetation cycle was examined. The mutation frequency increases as early as after the dose rate 4 mR/day. The dose rate of approximately 8 mR/day is necessary to double the mutation frequency.     

The origins of the genomes of Triticum biunciale,t. ovatum,t. neglectum,t. columnare,and t. rectum (poaceae) based on variation in repeated nucleotide sequences

The origins of the genomes of allotetraploid species Triticum biunciale, T. ovatum, T. neglectum, and T. columnare, and allohexaploid T. rectum were investigated by examining the presence of specific restriction fragments of repeated nucleotide sequences in DNAs of the polyploid species. The restriction fragments were detectable either in a single diploid Triticum species (unique characters) or a group of diploid species (unique shared characters). The analysis showed that Triticum biunciale and T. ovatum are closely related. In both species, one pair of genomes is closely related to the genome of T. umbellulatum and the other is a modified genome of T. comosum. The same genome formula, UUM°M°, is proposed for T. biunciale and T. ovatum. Potential reasons for the modification of the M° genome are discussed. Triticum neglectum and T. columnare are also closely related to each other and have the same genomes. They share the U genome with T. biunciale and T. ovatum, but their second pair of genomes is unrelated to the M° genome. No relationship was found of this genome to a genome of any extant diploid species of Triticum or any phylogenetic lineage leading to the extant diploid species. This unknown genome is designated X'.∗∗∗ The proposed genome formula for T. neglectum and T. columnare is UUX'X'∗∗∗. Hexaploid T. rectum originated from hybridization of one of the tetraploid species with the formula UUX'X', likely T. neglectum, with T. uniaristatum (genome N), and its genome formula is UUX'X'NN.     

Temporal and spatial distribution of malaria within an agricultural settlement of the Brazilian Amazon

Malaria has reemerged in tropical regions with rapid population growth and deforestation. The dynamics of malaria transmission in agricultural settlements of the Amazon have been poorly defined. We studied the spatial distribution of malaria incidence in Roraima, Brazil, using multi regression analysis on 12 parameters that described social, housing, and behavioral variables. Malaria cases were associated with the proximity of Anopheles darlingi breeding sites, the main vector in these areas. During the dry season, transmission was enhanced near a temporary river. Cases occurred throughout the year near fish‐farming dams. Epidemiological models derived from urban or riverine malaria are probably inadequate for describing disease transmission in agricultural settlements, where cases are clustered near breeding sites, while the majority of the population remains unaffected. Identification of these areas, associated with residual insecticide spraying or surveillance, may considerably decrease the costs of control efforts.     

Nutritional optimization of Arthrospira platensis for starch and Total carbohydrates production

Present study aims to optimize the production of starch and total carbohydrates from Arthrospira platensis. Growing concerns toward unprecedented environmental issues associated with plastic pollution has created a tremendous impetus to develop new biomaterials for the production of bioplastic. Starch-based biopolymers from algae serve as sustainable feedstock for thermoplastic starch production due to their abundant availability and low cost. A. platensis was cultivated in Zarrouk's medium at 32 ± 1°C and exposed to red light with a photoperiod of 12:12 hr light/dark. Growth kinetics studies showed that the maximum specific growth rate (μ_max) obtained was 0.059 day⁻¹ with the doubling time (t_d) of 11.748 days. Subsequently, Zarrouk's medium with different concentrations of sulfur, phosphorus and nitrogen was prepared to establish the nutrient-limiting conditions to enhance the accumulation of starch and total carbohydrates. In this study, the highest starch accumulated was 6.406 ± 0.622 mg L⁻¹ under optimized phosphorus limitation (0.025 g L⁻¹) conditions. Nitrogen limitation (0.250 g L⁻¹) results demonstrated significant influenced (p < 0.05) on total carbohydrates (67.573 ± 2.893 mg L⁻¹) accumulation in A. platensis. The starch accumulation in A. platensis was significantly affected (p < 0.05) by phosphorus limitation (0.0025 g L⁻¹). Subsequently, the optimized phosphorus concentration was coupled with mixotrophic cultivation to further enhance the starch accumulation. The results obtained indicated that, the starch (11.426 ± 0.314 mg L⁻¹) and carbohydrates (43.053 ± 2.986 mg L⁻¹) concentration obtained was significantly high (p < 0.05) under mixotrophic cultivation. Therefore, it shown that nutrient limitation and mixotrophic cultivation are viable strategies to enhance the accumulation of starch and total carbohydrates in A. platensis.     

血管紧张素Ⅱ、心房钠尿肽Ⅲ和血管升压素对大鼠脑片室旁核神经元放电活动的影响

在28个脑片观察了血管紧张素Ⅱ(AGⅡ)、心房钠尿肽Ⅲ(ANPⅢ)和血管升压素(AVP)三种多肽对101个下丘脑室旁核(PVN)神经元单位电活动的影响。脑片灌流AGⅡ(10~(-7)mol/L,3 min)后,28/50个单位(56.0％)放电频率明显增加,5/50个单位(10.0％)放电频率降低,17/50个单位(34.0％)无明显反应。AGⅡ对PVN放电单位的兴奋和抑制作用均可为AGⅡ受体阻断剂saralasin(10~(-6)mol/L)所阻断。脑片灌流ANPⅢ(10~(-7)mol/L,3 min)后,16/26个单位(61.5％)放电频率明显降低,1/26个单位(3.9％)放电频率增加,9/26个单位(34.6％)无明显反应。脑片灌流AVP,(10~(-7)mol/L,3min)后,19/25个单位(76.0％)放电频率明显增加,1/25个单位(4.0％)放电频率降低,5/25个单位(20,0％)无明显反应。在观察这三种多肽对同一PVN神经元的作用时,4个单位对AGⅡ和AVP均产生兴奋反应;2个单位对AGⅡ呈兴奋和被ANPⅢ所抑制;7个单位对AVP呈兴奋,而对ANPⅢ为抑制,未见到既对AGⅡ和AVP呈兴奋,又为ANPⅢ所抑制的单位。结果提示:AGⅡ,ANP和AVP三种多肽都能影响PVN神经元的自发电活动,PVN可能是神经内分泌和植物性功能调节的中枢整合部位之一。     

Presence of corticotropin-like and opiate-like hormones in rat and bovine placental tissues

Acid acetone powder of rat placentas was fractionated on Sephadex G-25 into a void volume peak (R-1) and three retarded peaks (R-2, R-3 and R-4). R-3 contained opiate-like activity and R-4 corticotropin-like activity, suggesting that separate corticotropin-like and opiate-like activities with molecular weight smaller than 5000 were present in rat placentas. Acid acetone powder of bovine placentas contained opiate-like activity which was unretarded on Sephadex G-25. Acid acetone powder of rat brains but not those of lungs, livers or kidneys possessed opiate receptor binding and steroidogenic activities, indicating that the activities in placentas were not due to enzymatically generated artifacts or to peptides contained in blood trapped in the organs.     

α-人心房钠尿多肽对大鼠血流动力学的作用

本工作观察了α-人心房钠尿多肽(α-Human atrial natriuretic polypeptide,α-hANP)对麻醉大鼠的血流动力学作用。静脉注射α-hANP(3μg/100g)后,动脉血压(ABP)、左室内压(LVP)、左室 dp/dt(LV dp/dt)、心指数(CI)和总外周阻力指数(TPRI)均明显下降,而心率(HR)无明显变化。切断迷走神经后,α-hANP 降压和 LV dp/dt 下降的程度虽有所减小,但与切断前相比无统计学意义。我们的结果表明,α-hANP 对麻醉大鼠的降压机制,在于外周血管舒张所致的总外周阻力减小,以及心肌收缩性能抑制而引起的心输出量降低。