Genetic diversity in sorghum [<Emphasis Type="Italic">Sorghum bicolor</Emphasis> (L.) Moench] germplasm from Southern Africa as revealed by microsatellite markers and agro-morphological traits     

Tiny Motlhaodi  Mulatu Geleta  Stephen Chite  Moneim Fatih  Rodomiro Ortiz  Tomas Bryngelsson 《Genetic Resources and Crop Evolution》2017,64(3):599-610

Cultivated sorghum [Sorghum bicolor (L.) Moench] is an important food security crop in the semi-arid regions of the world including Asia and Africa. Its genetic diversity is contained mostly in traditional varieties and modern cultivars used by farmers. In this study, agro-morphological traits and molecular markers were used to assess genetic diversity in 22 accessions of cultivated sorghum from five countries (Botswana, Namibia, Swaziland, Zambia and Zimbabwe) in the Southern African Development Community (SADC) region. The study revealed a significant variation among 22 accessions in both qualitative and quantitative morphological traits, indicating the accessions’ promising potential as breeding material. For molecular analysis, 11 microsatellite primer-pairs were used, and generated a total of 70 alleles across 20 accessions. Analysis of molecular variance revealed a high level of genetic variation; 67 % among the accessions and 10 % among the five countries. The patterns of genetic diversity and the relationships observed in this study should provide insights for genetic resource conservation and utilization of sorghum germplasm in the SADC region.  相似文献   

Formation of furan and methylfuran by maillard-type reactions in model systems and food     

Limacher A  Kerler J  Davidek T  Schmalzried F  Blank I 《Journal of agricultural and food chemistry》2008,56(10):3639-3647

The formation of furan and 2-methylfuran was studied in model systems based on sugars and selected amino acids. Both compounds were preferably formed under roasting conditions in closed systems yielding up to 330 micromol of furan and 260 micromol of 2-methylfuran per mol of precursor. The amounts obtained under pressure cooking conditions were much lower, usually below 20 micromol/mol, except for 2-furaldehyde, which yielded 70-100 micromol/mol of furan. Labeling studies indicated two major formation pathways for both furans: (i) from the intact sugar skeleton and (ii) by recombination of reactive C(2) and/or C(3) fragments. Under roasting conditions in the absence of amino acids, furan was mainly formed from the intact sugar skeleton. Formic and acetic acid were identified as byproducts of sugar degradation, indicating the split off of C(1) and/or C(2) units from hexoses. The presence of alanine, threonine, or serine promoted furan formation by the recombination of C(2) fragments, such as acetaldehyde and glycolaldehyde, which may originate from both sugars and amino acids. In aqueous solution, about half of furan was generated by the recombination of sugar fragments. 2-Methylfuran was preferably formed in the presence of amino acids by aldol-type reactions of C(2) and C(3) fragments with lactaldehyde as a key intermediate, the Strecker aldehyde of threonine. The total furan levels in cooked vegetables were increased by spiking with hexoses. However, in pumpkin puree, only about 20% of furan was formed from sugars, preferably from the intact carbon skeleton.  相似文献   

Cloning and expression of buffalo active chymosin in Pichia pastoris     

Vallejo JA  Ageitos JM  Poza M  Villa TG 《Journal of agricultural and food chemistry》2008,56(22):10606-10610

To date, only recombinant chymosin has been obtained in its active form from supernatants of filamentous fungi, which are not as good candidates as yeasts for large-scale fermentations. Since Bos taurus chymosin was cloned and expressed, the world demand for this protease has increased to such an extent that the cheesemaking industry has been looking for novel sources of chymosin. In this sense because buffalo chymosin has properties that are more stable than those of B. taurus chymosin, it may occupy a space of its own in the chymosin market. The main objective of the present work was the production of active recombinant buffalo chymosin in the culture supernatant of Pichia pastoris . This yeast has demonstrated its usefulness as an excellent large-scale fermentation tool for the secretion of recombinant foreign proteins. RNA was extracted from the abomasum of a suckling calf water buffalo ( Bubalus arnee bubalis ). Preprochymosin, prochymosin, and chymosin DNA sequences were isolated and expressed into P. pastoris. Only the recombinant clones of P. pastoris containing the prochymosin sequence gene were able to secrete the active form of the chymosin to the culture supernatant. This paper describes for the first time the production of active recombinant chymosin in P. pastoris without the need of a previous in vitro activation. The new recombinant yeast strain could represent a novel and excellent source of rennet for the cheesemaking industry.  相似文献   

Investigations of exogenous applications of carbohydrates on the growth and vitality of live oaks     

Tomas Martinez-Trinidad  W. Todd Watson  Michael A. Arnold  Leonardo Lombardini 《Urban Forestry & Urban Greening》2009,8(1):41-48

Some practitioners within the green industry have lauded the application of sugar-containing products to the soil around trees as a method to improve plant health. A research study was initiated to evaluate the effects of exogenous applications of glucose and starch on the growth and vitality of healthy live oaks (Quercus virginiana P. Miller). Glucose, starch, or a 50:50 mixture of both carbohydrates were applied as soil drenches around 60 young live oaks growing at a field nursery. Carbohydrates were dissolved in water and applied at concentrations of 0, 40, 80, and 120 g L^?1 within 0.5 m from the trunk. Solutions were applied using 10 L per application every four months during an 18-month period. Trunk diameter, root and canopy growth, and carbohydrate content of twigs and roots were measured every four months, and net photosynthetic rate, chlorophyll fluorescence, and soil respiration were measured every six months. Tissue samples from twigs and roots were collected after 16 months to measure carbon isotope composition (δ¹³C) as an indicator of carbohydrate uptake. Chlorophyll fluorescence varied throughout the experiment but did not demonstrate a clear trend. Higher carbohydrate applications did influence the concentration of glucose in twigs although the results did not clearly indicate that this effect was caused by an uptake of glucose from roots. δ¹³C signatures did not provide any evidence about potential carbohydrate uptake. Even though there was a significant increase in soil respiration after being treated with starch, no significant increase in growth or vitality was detected on healthy live oaks.  相似文献   

Soil phosphorus testing for intensive vegetable cropping     

Stany Vandermoere  Tomas Van De Sande  Greet Tavernier  Lore Lauwers  Ellen Goovaerts  Joris De Nies  Stefaan De Neve 《植物养料与土壤学杂志》2020,183(3):345-354

Environmental concerns and rapidly decreasing phosphorus (P) resources caused a renewed interest in improving soil P tests for a more efficient P fertilization. This led to the development of better P fertilizer recommendation systems for major arable crops and grass. Nevertheless, these P fertilizer recommendation systems seem to fail for intensive vegetable crops, with often a very short growing season and limited rooting system. This leads to low P use efficiencies in the horticultural sector. In order to address this problem we set up a study to answer following questions: (1) which soil P test predicts the plant available P content for intensive vegetable crops the best and (2) can new insights, such as combining different soil P tests, improve P fertilizer recommendations for intensive vegetable crops? To this end, bulk samples of 41 soils with very different P status (based on ammonium lactate extractable P) were collected. The plant available P content of these soils was determined using six commonly used soil P tests (P‐CaCl₂, P‐water, P‐Olsen, P‐acetate, P‐lactate, and P‐oxalate) and a P fertilizer pot experiment with endive (a very P sensitive vegetable crop) was conducted. Six pots of each soil were planted with endive. Three of these pots received no P fertilization (0P) and three pots received ammonium polyphosphate equivalent to 24 kg P ha^?1 (24P). All other factors were kept constant. Relative crop yield of the 0P fertilized plants compared to the 24P fertilized plants was determined. Plotting these relative yields against the P status of the soil per soil P test allowed to fit a Mitscherlich curve through the data. Also the combination of two different soil P tests to predict the relative yield with a Mitscherlich equation was evaluated. The coefficients of variation of the soil P tests, the R² values and the relative standard errors of the parameter estimates revealed that P‐acetate and P‐water predicted the relative yield of the 0P plants the best and that combining two different soil P tests gave no extra predictive power. This finding may form the basis for the development of a new P fertilizer recommendation system for intensive vegetable crops, leading to an improved P use efficiency in horticulture. In order to develop this new system more data relating soil P test values with RY of intensive vegetable crops should be collected.  相似文献   

基于EfficientDet网络的湖羊短时咀嚼行为识别方法     

陆明洲  梁钊董  NORTON Tomas  张生福  沈明霞 《农业机械学报》2021,52(8):248-254，426

为分析羊进食行为、自动估算其进食量,提出一种从舍饲湖羊采食视频中自动识别其短时咀嚼行为的方法。首先,针对舍饲湖羊采食区域特点,在EfficientDet网络架构中增加目标框筛选模块,检测视频帧中羊嘴张开、上下颌错开及闭合3种状态,根据羊脸与相机拍摄角度的方位关系检测羊嘴状态,并为各状态赋编码值;然后,利用正则表达式提取连续视频帧中的一次上下颌张合对应的羊嘴状态编码值序列片段;最后,针对羊侧脸面对相机咀嚼、抬头正脸面对相机咀嚼、低头正脸面对相机咀嚼以及鸣叫等一次上下颌张合动作对应的羊嘴状态编码值序列片段构建分类规则,实现短时咀嚼行为的自动识别。对比了基于EfficientDet-D0~D4、YOLO v5和SSD网络的羊嘴状态检测性能,结果表明,改进的EfficientDet-D1网络能以28.18 f/s的传输速率,获得95.64%和98.84%的羊嘴状态检测精确率和均值平均精确率,优于YOLO v5和SSD网络。利用湖羊采食视频测试EfficientDet-D1网络结合正则表达式的湖羊短时咀嚼行为识别分类规则性能,结果表明,分类规则能以91.42%的自动识别正确率和90.85%的平均正确率直接从视频中提取湖羊短时咀嚼行为发生次数和持续时长。本研究将基于视频的湖羊短时咀嚼行为识别问题转换为羊嘴状态编码值序列分类问题,降低了分类模型的复杂度,为湖羊短时咀嚼行为的自动识别提供了一种新的研究思路。  相似文献   

Growth hormone increases whole-body protein turnover in growing pigs.     

F M Tomas  R G Campbell  R H King  R J Johnson  C S Chandler  M R Taverner 《Journal of animal science》1992,70(10):3138-3143

Ten pigs with an average initial live weight of 65 kg were used to investigate the effects of daily exogenous porcine pituitary growth hormone (pGH; .1 mg.kg-1.d-1) for a 13-d period on N retention and whole-body protein turnover. Feed intake was restricted to both the control (treated with excipient) and pGH-treated groups to ensure that animals in each group consumed equal amounts. Whole-body protein turnover was estimated from the excretion of 15N in urinary urea and ammonia after a single oral dose of [15N]glycine. Nitrogen balance and whole-body N flux were increased by 35 to 40% with pGH treatment (P less than .001). Protein synthesis and breakdown were increased by 56 and 59% (P less than .001), respectively, in pGH-treated pigs relative to controls. These higher rates of protein turnover seemed to lower slightly the efficiency of the metabolic process for protein deposition. However, the absolute increment in protein synthesis rate was greater than that for breakdown, leading to the increased net N retention. Thus, pGH treatment improved the utilization of dietary amino acids for protein deposition.  相似文献   

Rates of muscle protein breakdown in chickens selected for increased growth rate, food consumption or efficiency of food utilisation as assessed by N tau-methylhistidine excretion     

F M Tomas  L M Jones  R A Pym 《British poultry science》1988,29(2):359-370

1. N tau-methylhistidine excretion, growth rate, food consumption and body composition was determined in 12 4 to 5 week old chickens sampled from each of 4 lines selected for increased body-weight gain (line W), for increased food consumption (line F), for improved efficiency of food utilisation (line E) or at random (line C), after 12 generations of selection. 2. The use of N tau-methylhistidine as an index of myofibrillar protein breakdown was validated in male and female chickens of lines E and F by following the fate of injected N tau-(14CH3)methylhistidine. Most of the radioactivity (79.3 +/- 1.1%) was excreted in 4 d, with the remainder retained in the carcase. In excreta, 94 +/- 2% of the radioactivity was associated with free N tau-methylhistidine and for the carcase, this value was 88 +/- 3%. 3. In the main experiment, final body weights averaged 497, 651, 588 and 537 g and food: gain ratio averaged 2.47, 2.21, 3.14 and 2.06 for lines C, W, F and E respectively, Carcase protein content (g/100 g body weight) was not different between the lines. 4. N tau-methylhistidine excretion was 5.86, 5.48, 6.43 and 4.99 mumoles/mole carcase-N/d for lines C, W, F and E, respectively. The rate for line F was significantly higher than for lines W and C and that for line E was significantly less than for the control line. 5. The N tau-methylhistidine excretion rate was positively correlated with food: gain ratio. 6. Selection for rapid growth, high food consumption or improved food utilisation results in changes in N tau-methylhistidine excretion which suggest proportionate changes in muscle protein turnover.  相似文献   

Screening the primary gene pool of field pea (Pisum sativum L. subsp. sativum) in Ethiopia for resistance against pea weevil (Bruchus pisorum L.)     

Abel Teshome  Esayas Mendesil  Mulatu Geleta  Derege Andargie  Peter Anderson  Birgitta Rämert  Emiru Seyoum  Ylva Hillbur  Kifle Dagne  Tomas Bryngelsson 《Genetic Resources and Crop Evolution》2015,62(4):525-538

  相似文献   

Ontogenetic variability of maternal effects in an iteroparous fish          下载免费PDF全文

Sara R. Andree  Zachary S. Feiner  Jacob W. Bledsoe  Aaron M. Cragun  Tomas O. Höök 《Ecology of Freshwater Fish》2015,24(3):384-396

Maternal effects have been observed to interact with genotypic and environmental influences to structure offspring phenotypes across a wide variety of taxa. In fishes, maternal effects may be especially important due to their potential influence on development and survival during early ontogeny – a period with high potential for population regulation. While previous studies have confirmed that maternal effects on offspring phenotype are common in fishes, the consistency with which they positively affect offspring fitness throughout early ontogeny remains largely unknown. We examined maternal effects on offspring fitness by quantifying relationships between maternal (length, mass and age), egg (diameter, mass and density) and larval traits (length, yolk‐sac volume and survival) in yellow perch (Perca flavescens). Consistent with several past studies, positive relationships among maternal and egg traits were evident. While egg mass was positively related to larval size at hatching, direct relationships between maternal and larval metrics were not apparent. Larval survival appeared to have two critical periods; in contrast with expectations, survival in the first 5 days posthatch was strongly negatively related to female size and age, while survival over the following 9 days was unrelated to maternal traits. Throughout the study, survival was positively related to yolk‐sac volume. Our unexpected observation of a negative relationship between maternal size and age and initial larval survival indicates that maternal effects may not be consistent throughout larval ontogeny. In fact, maternal effects appear to be dynamic influences on offspring fitness, and may have complex effects on individual‐ and population‐level reproductive success.  相似文献