Production of extracellular enzymes by Thermomonospora curvata during growth on protein-extracted lucerne fibres

After extraction of food protein from lucerne, the residual fibre was used as a carbon and energy source by the thermophilic actinomycete, Thermomonospora curvata. Induction of catabolic exoenzymes during growth for 7 d on the fibre at 53°C in a mineral salts minimal medium was compared with that on a variety of other inductive substrates. A fibre concentration of 1.5% (w/v) was optimal for total protein secretion. The fibre was a poor substrate for amylase production due to lack of inducer rather than to catabolite repression by soluble sugars released during degradation. β-Glucosidase release during growth on the fibre was about 10 times that observed in cultures grown on cellobiose or cellulose, but production of other cellulolytic enzymes was about one-half that produced on cellulose. Pectinolytic activity (measured as polygalacturonate lyase) was equal to that produced on pectin. Cells grown on the fibre released about eight times as much proteinase as those grown on cellulose, but proteolytic activity was transient and decreased rapidly during later growth. Xylanase appeared to be co-ordinately induced with cellulolytic enzymes; comparable maximal activities, observed during growth on either the fibre or cellulose, were three times that produced on xylan or xylose.     

Food selection by the silver leaf monkey,Trachypithecus auratus sondaicus,in relation to plant chemistry

Summary Samples of leaves and fruits exploited as food items byTrachypithecus auratus sondaicus were analysed for nitrogen content, acid detergent fibre (ADF), pepsin cellulase digestibility (CDIG), condensed tannins (CT), total phenolics (TP) and protein precipitation capacity (PP) and compared with fruits and leaves not eaten. Differences in chemical measures for items eaten and not eaten were not statistically significant but trends indicate that leaves may have been selected for their lower fibre content and greater digestibility. Fruits eaten also had a higher mean level of CDIG and lower mean level of ADF than fruits not eaten but these measures are not considered to be of major importance in fruit selection as CDIG was lower and ADF higher in fruits eaten than in leaves eaten. Levels of CT, TP and PP capacity were higher in fruits eaten than in fruits not eaten but lower in leaves eaten than in leaves not eaten. The role of tannins and phenolics in food selection is discussed. Leaves (and fruits) were not strongly selected on the basis of protein content. Approximately half the dietary intake ofT. auratus sondaicus was leaves, a protein-rich food source. Possibly, protein levels in foliage at Pangandaran were sufficient that selection for this nutrient was not required. A nutrient other than protein (for example, soluble carbohydrates) may have been maximised through food selection. The protein/ADF ratio may provide an indicator of the acceptability of foliage in a habitat as potential food for a colobine. However, this ratio did not govern food selection byT. auratus sondaicus at Pangandaran.     

More efficient mastication allows increasing intake without compromising digestibility or necessitating a larger gut: Comparative feeding trials in banteng (Bos javanicus) and pygmy hippopotamus (Hexaprotodon liberiensis)

The digestion of plant material in mammalian herbivores basically depends on the chemical and structural composition of the diet, the mean particle size to which the forage is processed, and the ingesta retention time. These different factors can be influenced by the animal, and they can presumably compensate for each other. The pygmy hippopotamus, a non-ruminating foregut fermenter, has longer mean retention times than ruminants; however hippos do not achieve higher (fibre) digestibilities on comparable diets, which could be due to ineffective mastication. We performed feeding trials with six pygmy hippos (Hexaprotodon liberiensis) and six banteng cattle (Bos javanicus) on a grass diet. As predicted, both species achieved similar dry matter, organic matter, crude protein and gross energy digestibilities. However, neutral and acid detergent fibre digestibility was lower in pygmy hippos. Apparently, in these species, fibre digestibility was more influenced by particle size, which was larger in pygmy hippos compared to banteng, than by retention time. In spite of their higher relative food intake, the banteng in this study did not have greater relative gut fills than the hippos. Ruminants traditionally appear intake-limited when compared to equids, because feed particles above a certain size cannot leave the rumen. But when compared to nonruminating foregut fermenters, rumination seems to free foregut fermenters from an intrinsic food intake limitation. The higher energy intakes and metabolic rates in wild cattle compared to hippos could have life-history consequences, such as a higher relative reproductive rate.     

Physiological factors affecting the rapid decrease in protein assimilation efficiency by a caterpillar on newly‐mature tree leaves

Lymantria dispar L. caterpillars have a decreased ability to assimilate protein from mature leaves of red oak (Quercus rubra) compared with young, expanding leaves. The present study determines whether the drop in protein assimilation efficiency (PAE) occurs during the rapid phase of leaf maturation. Several mechanisms that might account for decreased PAE are also examined: mature leaf tissues could resist being chewed efficiently, protein in mature leaf tissues could become difficult to extract, and other nutrients in mature leaves might become growth limiting. The entire seasonal decrease in PAE occurs rapidly (in less than 2 weeks), when the leaves finished expanding. The maturation process is characterized by increased levels of fibre and decreased levels of water but no significant changes in the levels of protein or carbohydrates. Despite increased fibre in mature leaves, they are not chewed into larger food particles than are immature leaves. Carbohydrate assimilation efficiencies remain high on mature leaves, and signs of limiting water levels in larvae of L. dispar on mature leaves are not observed. The most important finding in the present study is the decreased extractability of protein in food particles from mature leaves, which plays a major role in explaining the rapid decrease in PAE. It is hypothesized that structural changes in cell walls during the rapid process of leaf maturation decrease protein extractability, which, in turn, greatly decreases the nutritional quality of mature oak leaves for caterpillars. The results of the present study therefore suggest a general mechanism to help explain the widely documented decrease in the nutritional quality of the mature leaves of many tree species for herbivorous insects.     

How do differences in species and part consumption affect diet nutrient concentrations? A test with red colobus monkeys in Kibale National Park,Uganda

Within a primate species, diet can be highly variable in composition, even at small spatial scales within the same forest, or temporally, suggesting that primates use different plant species and parts to meet similar nutritional needs. To test whether such differences in the plant species and parts that primates eat affects the nutrient concentrations that they obtain, we observed feeding of seven groups of red colobus monkeys ( Procolobus rufomitratus) residing in Kibale National Park, Uganda. The different groups consumed mostly young leaves from many of the same plant species, but spent different amounts of time feeding on them. As protein and fibre are suggested to be important determinants of colobine food choice and abundance, we analysed multiple samples of 47 food species for protein and fibre. Despite the differences in the plant species and parts eaten, the protein and fibre concentrations for the seven red colobus groups were similar. Our results suggest that colobus monkeys eating diets with differing amounts of species and parts may ultimately receive similar concentrations of nutrients.     

豆粕和土豆蛋白替代饲料中鱼粉对异育银鲫生长及能量收支的影响

利用全能量收支同步测定呼吸仪系统测定了三种不同蛋白源(鱼粉、豆粕、土豆蛋白)饲料对银鲫生长及能量收支各组分的影响。对照饲料全部以鱼粉为蛋白源,另两种饲料中30％的蛋白质分别来自豆粕和土豆蛋白。试验结果表明,银鲫对三种蛋白源的饲料的摄食率,食物转化效率均有显差异,以鱼粉组最高,豆粕其次,土豆蛋白最低。能量收支各组分也均有显差异,能量收支式如下：鱼粉88．1C=13．77F 2．95U 24．1G 41．8R 豆粕 102．3C=17．1F 2．8U 16．4G 55．4R土豆蛋白105．5C=14．9F 1．3U 14．4G 67．4R式中C、F、U、G、R分别代表摄食能、排粪能、排泄能、生长能、代谢能。     

Swedes (Brassica napus) for growing pigs: Chemical composition and use as a replacement for barley in the diet

Macerated swedes (variety Balmoral) were used in diets for growing pigs and contained in dry matter (DM), gross energy 18.6 MJ/kg, crude protein 12.8%, true protein 5.0%, total lysine 0.40%, methionine + cystine 0.26%, total soluble sugars 40.8%, acid-detergent fibre 20.6% and ash 10.9%.One hundred pigs were grown from a mean live weight of 56 kg on either a control diet, containing 89% barley and 9% soya bean meal on a DM basis, or on diets in which swede DM replaced 20 or 40% of barley DM. The results suggest that for equivalent carcass growth approximately 1.5 units of swede DM are required for each unit of barley DM replaced.Swedes are a potentially valuable food, but further investigation is required into factors affecting their nutritive value for pigs, particularly varietal differences, the effect of within-season changes in chemical composition and the utilization of the energy, protein and fibre components of the organic matter.     

A comparison of three fibre methods for predicting the metabolizable energy content of sorghum grain for poultry

An apparatus designed to simplify analytical procedures for determining fibre in food was used to measure fibre of similar composition to crude fibre, acid-detergent fibre and neutral-detergent fibre in 27 samples of sorghum grain. The metabolizable energy content of these grains for poultry was predicted from the three fibre methods with precision, respectively, of ± 0.49, ± 0.62 and ± 0.53 MJ/kg dry matter. These values corresponded to coefficients of variation of ± 3.0, ± 3.8 and ± 3.3%.The three fibre fractions were highly correlated with each other, and so a simple method that can measure a part of the total fibre is suitable for predicting the energy value of sorghum grain for poultry.     

Dietary ratio of protein to carbohydrate induces plastic responses in the gastrointestinal tract of mice

Some vertebrates change the size of their digestive system in response to quantity and fibre content of ingested food, but the effects of dietary nutrients on gut structure remain poorly understood. Here we investigate how the protein to carbohydrate ratio of diets affects the mass of the gastrointestinal tract in mice. We fed 6-week-old male mice one of five isocaloric diets differing only in protein to carbohydrate ratio (the “no-choice” treatments), while a further four treatment groups received nutritionally complementary food pairings from which they could self-select a diet (the “choice” treatments). After 32 days, we measured the resulting dry mass of stomachs, intestines, caeca and colons. In the no-choice treatments, the stomachs were heavier in the mice fed diets containing more protein and less carbohydrate, indicating that larger stomachs may be needed for efficient digestion of the protein-rich food. In contrast, intestines, caeca and colons were heavier when diets contained more carbohydrates and less protein. This response may function to increase the digestive rate of carbohydrates when the dietary content of this macronutrient increases, but it may also indicate a compensatory response to increase amino acid uptake from a protein-deficient food. Mice in the choice treatments self-selected a diet with a protein to carbohydrate ratio of 0.46, and had gut dimensions similar to the expectation derived from no-choice treatments for this diet composition. Our results provide an example of plasticity in the differential allocation of resources to organ function, which is triggered by variation in resource quality.     

The nutritional consequences of foraging in primates: the relationship of nutrient intakes to nutrient requirements.

Many studies have examined the proportion of time that primates devote to feeding on various types of food, but relatively little is known about the intake rates associated with each food. However, the nutritional consequences of foraging can only be interpreted by comparing nutrient intakes with estimated nutrient requirements. The energy available to primates from ingested foods will depend both on the composition of the food and the extent to which various constituents, including fibre fractions, are digested. Both human and non-human primates have relatively low requirements for protein as a consequence of slow growth rates, small milk yields and relatively dilute milk. Because the nutrient demands of growth and reproduction are spread out over time, it appears that primates do not need to seek out foods of particularly high nutrient density, except perhaps during weaning. Although food selection in some species of primates appears to be correlated with the protein concentration of foods, it is unlikely that high dietary protein levels are required, at least when foods of balanced amino acid composition (such as leaves) are included in the diet.     

植食性小哺乳类营养生态学的研究：高原鼠兔的食物选择模式与食物质量

本文报道了高原鼠兔(Ochotona curzoniae)的食物模式,食物选择指数及食物项目的营养成分,并探讨食物质量与食物选择的关系。高原鼠兔主要选食双子叶植物叶片。食物组成与饲料可利用量的比较分析,揭示出高原鼠兔对各种食物项目的选择程度。在排除其它营养因子的作用后,复回归分析的结果表明,食物百分率与磷含量之间具有显著的正相关。各种食物项目不同营养成分与食物百分率之间相关关系不一致。从而进一步验证了食物选择决定于饲料可利用量和食物质量的假设。     

Food selection by two South-east Asian colobine monkeys (Presbytis rubicunda and Presbytis melalophos) in relation to plant chemistry

The diets of the banded leaf monkey ( Presbytis melalophos ) at Kuala Lompat in the Krau Game Reserve of West Malaysia and the red leaf monkey ( Presbytis rubicunda ) in Sepilok Virgin Jungle Reserve, Sabah, East Malaysia have been examined in relation to plant chemistry. Both monkeys spent about half their time eating foliage, and about half their time eating fruits and seeds. They both favoured leaves with high digestibility (due to relatively low levels of fibre) and high levels of protein, a combination found predominantly in young leaves and some flowers. The monkeys appeared to favour seeds and fruits with high concentrations of storage carbohydrates or fats, but not those rich in simple sugars. Selection of seeds and fruits was not correlated with protein content.
An analysis of the fibre and protein contents of foods showed that, on an annual basis, the two monkeys achieved a comparable intake for both items. However, these diets were obtained in radically different ways. Presbytis melalophos was able to eat foliage from many of the common tree species in its home range, whereas P. rubicunda relied on rare trees and lianas. This difference is attributed to the very high density of Dipterocarpaceae at Sepilok, a tree family that provides little food for colobines. The rarity of P. rubicunda's food plants at Sepilok is considered to be the main reason for the greater home range size and lower population density in comparison to P. melalophos.
Finally, the biochemical profiles of the young leaf diet of these two monkeys were compared with previously published information on two African and one south Indian colobines. In many respects the intake of supposed critical components, protein and fibre, showed marked similarities between different animals, considering contrasts in their habitats.     

Wasted Food: U.S. Consumers' Reported Awareness,Attitudes, and Behaviors

The U.S. wastes 31 to 40% of its post-harvest food supply, with a substantial portion of this waste occurring at the consumer level. Globally, interventions to address wasted food have proliferated, but efforts are in their infancy in the U.S. To inform these efforts and provide baseline data to track change, we performed a survey of U.S. consumer awareness, attitudes and behaviors related to wasted food. The survey was administered online to members of a nationally representative panel (N=1010), and post-survey weights were applied. The survey found widespread (self-reported) awareness of wasted food as an issue, efforts to reduce it, and knowledge about how to do so, plus moderately frequent performance of waste-reducing behaviors. Three-quarters of respondents said they discard less food than the average American. The leading motivations for waste reduction were saving money and setting an example for children, with environmental concerns ranked last. The most common reasons given for discarding food were concern about foodborne illness and a desire to eat only the freshest food. In some cases there were modest differences based on age, parental status, and income, but no differences were found by race, education, rural/urban residence or other demographic factors. Respondents recommended ways retailers and restaurants could help reduce waste. This is the first nationally representative consumer survey focused on wasted food in the U.S. It provides insight into U.S. consumers’ perceptions related to wasted food, and comparisons to existing literature. The findings suggest approaches including recognizing that many consumers perceive themselves as being already-knowledgeable and engaged, framing messages to focus on budgets, and modifying existing messages about food freshness and aesthetics. This research also suggests opportunities to shift retail and restaurant practice, and identifies critical research gaps.     

Energy metabolism and protein balance in growing rats fed different levels of dietary fibre and protein

A study was performed to investigate the effect of different levels of dietary fibre (DF) and dietary protein on visceral organ size, digestibility, nitrogen balance and energy metabolism in rats. Thirty-six male Wistar rats, initial body weight about 76 g, were used in a factorial design consisting of three levels of DF (low, 100 g/kg DM; medium, 250 g/kg DM and high, 290 g/kg DM) and two levels of dietary protein (low, 120 g/kg DM and high, 223 g/kg DM). The added fibre source was soybean hulls and Danish fish meal was used as sole source of dietary protein. Measurements of gas-exchange were done on six rats (one group) while urine and faeces were collected individually. The ratio of food/empty body gain increased (P < 0.05) with increasing DF and decreasing levels of dietary protein. The weight of the digestive tract was larger (P < 0.05) in rats fed the high fibre diet than in those fed the low fibre diet. The digestibility of nutrients and energy decreased linearly with increasing level of soybean fibre (P < 0.05). An increased intake of DF was associated with a concomitant loss of protein and energy to faeces. The microbial degradation of NSP and other unabsorbed carbohydrates caused considerably changes in N metabolism of the colon. In rats fed the low protein diets increased levels of DF decreased N excretion in urine and increased N excretion in faeces, while the ratio of retained/digested protein remained constant. When rats were fed the high protein diet protein retention dropped in response to DF both absolute and relative to digested amount, indicating that energy intake could be a limiting factor. Heat production as a percentage of metabolizable energy (HP/ME) was higher (P < 0.05) in rats fed the low protein diet than in rats fed the high protein diet, but no significant difference was found among DF levels.     

Nutrient digestibility and growth responses of rainbow trout (Salmo gairdneri) fed different levels of cassava and rice

Seven groups of fingerling rainbow trout (Salmo gairdneri) were fed for 10 weeks on 0%, 10%, 20% and 30% of cassava or rice in isonitrogenous diets.Optimum growth and food utilisation was at 20% dietary cassava. High fibre content of the control diet did not suppress protein digestibility in this group. Rather, at all levels, protein digestibility was good and remained between 84.4% and 87.5%. However, in the control group, carbohydrate digestibility was very poor. The cassava diet which had the highest digestible energy as carbohydrate produced the best growth performance, food utilization and protein sparing. At the levels studied, the dietary carbohydrates produced no hyperglycaemic effect on the fish. There was no evidence of drastic adverse effects on the tissue and liver composition of the fish receiving these carbohydrates.     

Differences in protein mobilization between ventral and dorsal parts of white epaxial muscle from fed, fasted and refed white sturgeon (Acipenser transmontanus)

The effect of starvation-refeeding on protein mobilization in the lateral line, lateral (midway between lateral line and dorsum) and dorsal parts of white sturgeon ( Acipenser transmonlanus ) white epaxial muscle (type IIB) were compared by measuring muscle cross-sectional fibre areas. Effects on red (type I) and pink (type IIA) muscle were also studied. Fish starved throughout the experiment (5 weeks) showed a uniform response, i.e. the cross-sectional fibre area decreased at all sampled locations in the white muscle as well as in red and pink muscle. Fibre size in fish refed for 3 weeks after 2 weeks of fasting (S/F) was reduced mainly in the dorsal region of the white muscle. Starvation for 3 weeks after 2 weeks of initial feeding (F/S) also reduced fibre size mainly in the dorsal regions of the white muscle and in the pink muscle. The results indicate that in sturgeon exposed to short periods of low food availability, protein is utilized preferentially from trie more dorsal regions of the white epaxial muscle and from pink muscle. Protein in white muscle located closer to the lateral line and in red muscle seems to be spared. With the onset of refeeding, protein deposition occurred rapidly in pink muscle, but was delayed significantly in the dorsal part of the white muscle.     

Differences in food assimilation between two coot species assessed with stable isotopes and particle size in faeces: linking physiology and conservation

The red-knobbed coot Fulica cristata experienced a dramatic population decline in Spain, where the common coot F. atra does not face conservation problems. This is puzzling because both species have similar ecologies. It has been suggested that habitat alterations affected the quality of food plants, and this impacted differentially both coots. To verify this, we conducted experiments to determine the assimilation efficiency of both species in relation to food quality. Two types of diets differing in fibre content (commercial food and Potamogeton pectinatus) were offered to captive red-knobbed and common coots, during both spring and autumn. We examined variations in faecal particle size among coot species and diets, indicative of the facility with which food can be assimilated, and used the stable isotope technique to study differences between coot species in stable isotope fractionations from consumption to excretion. Faecal particle size was larger in red-knobbed than in common coots when fibre content was high, but was similar when it was low. Faecal particle sizes were larger in autumn, when fibre content was higher, than in spring. In general, delta(15)N in faeces of red-knobbed coots was greater than in faeces of common coots. These results suggest that the digestive efficiency of the red-knobbed coot was lower than that of the common coot, and that the differences increased when the fibre content in food plants increased. Managers should try to make available to coots wetland habitat with high quality food, which may be facilitated by prolonging the hydroperiods.     

麻疯树脂酶全长基因克隆、表达及其蛋白质结构预测

脂酶(Lipase,EC3.1.1.3)是普遍应用于皮革、饲料及生物柴油工业的工业酶制剂,具有广泛的应用价值。目前对植物来源的脂酶研究较少。本研究用在生物柴油中具有应用前景的油料植物——麻疯树(Jatrophacurcas)作为研究对象,克隆了该物种的脂酶基因(JcLIP)。通过多序列比对并结合物种的亲缘关系设计了具有较高特异性的简并引物,通过使用RT-PCR和RACE技术,最终获得了麻疯树脂酶基因的全长序列并成功地在大肠杆菌中表达,酶活测定结果表明,麻疯树脂酶在大肠杆菌中表达在包涵体中,但是能产生具有活力的蛋白质,酶活约为0.8U.mL-1。结构预测和比较表明,JcLIP蛋白质具有脂酶的结构核心和催化活性中心,而在非核心区具有较毛霉脂酶更多的插入和随机卷曲,这可能是决定二者之间酶活差异的重要原因。     

麻疯树脂酶全长基因克隆、表达及其蛋白质结构预测

脂酶(Lipase, EC3.1.1.3)是普遍应用于皮革、饲料及生物柴油工业的工业酶制剂, 具有广泛的应用价值。目前对植物来源的脂酶研究较少。本研究用在生物柴油中具有应用前景的油料植物——麻疯树(Jatropha curcas)作为研究对象, 克隆了该物种的脂酶基因(JcLIP)。通过多序列比对并结合物种的亲缘关系设计了具有较高特异性的简并引物, 通过使用RT-PCR和RACE技术, 最终获得了麻疯树脂酶基因的全长序列并成功地在大肠杆菌中表达, 酶活测定结果表明, 麻疯树脂酶在大肠杆菌中表达在包涵体中, 但是能产生具有活力的蛋白质, 酶活约为0.8 U.mL-1。结构预测和比较表明, JcLIP蛋白质具有脂酶的结构核心和催化活性中心, 而在非核心区具有较毛霉脂酶更多的插入和随机卷曲, 这可能是决定二者之间酶活差异的重要原因。     

Transient transformation of the obligate biotrophic rust fungus Uromyces fabae using biolistics

Obligate biotrophic pathogens like the rust fungi are important plant pathogens causing enormous losses on food, forage and biomass crops. The analysis of the molecular details underlying obligate biotrophic host-parasite interactions is mainly hampered by the fact that no system for transformation is available for most obligate biotrophic organisms. Here we report the transient transformation of Uromyces fabae, an obligate biotrophic rust fungus using a biolistic approach. Biolistic bombardment of U. fabae urediospores was used to deliver different color markers (β-glucuronidase (GUS), intron green fluorescent protein (iGFP) and red fluorescent protein (DsRed) and/or a selection marker. Endogenous regulatory elements from U. fabae plasma membrane ATPase (Uf-PMA1) were used to drive expression of the transgenes. In addition to the delivery of color markers, an in planta selection procedure using the fungicide Carboxin was established allowing the propagation of transformants. In addition to mere cytoplasmic expression of the color markers, a nuclear localization signal was fused to DsRed (pRV115-NLS) targeting the fluorescent marker protein to the nuclei. A?procedure for the genetic modification of U. fabae was established. The method can be easily adapted for use with other obligate biotrophic fungi. This provides the basis for a more in depth analysis of the molecular principles governing the obligate biotrophic lifestyle.