Factors affecting the feeding quality of barley for ruminants

Variation in the nutritive value of barley is well documented. Although bulk density is a convenient means of evaluating barley, it does not fully account for differences observed in animal performance from feeding different sources of barley. Recent data indicate that starch and (or) fiber content may be more reliable criteria for evaluating sources of barley. As progress has been made toward higher starch content and plumper barley, greater attention should be given to proper processing of barley before feeding. Improper processing might well negate potential improvements expected from higher-quality barley.     

Conceptus-modulated innate immune function during early pregnancy in ruminants: a review

This review focuses on the innate immune events modulated by conceptus signaling during early pregnancy in ruminants. Interferon-tau (IFN-τ) plays a role in the recognition of pregnancy in ruminants, which involves more than the inhibition of luteolytic pulses of PGF2α to maintain corpus luteum function. For successful pregnancy establishment, the allogenic conceptus needs to prevent rejection by the female. Therefore, IFN-τ exerts paracrine and endocrine actions to regulate the innate immune system and prevent conceptus rejection. Additionally, other immune regulators work in parallel with IFN-τ, such as the pattern recognition receptors (PRR). These receptors are activated during viral and bacterial infections and in early pregnancy, but it remains unknown whether PPR expression and function are controlled by IFN-τ. Therefore, this review focuses on the main components of the innate immune response that are involved with early pregnancy and their importance to avoid conceptus rejection.     

Factors affecting feeding decisions in a group of black lemurs confronted with novel food

The behavior of black lemurs presented with novel and familiar food in the presence or absence of the dominant female was analyzed in order to examine the influence of the latter on feeding decisions at a group level. Results showed that individual learning occurred with high quality food, while the dominant female influenced the eating behavior of other group members when food was of low attractiveness or unfamiliar.     

Factors affecting bio-oxidation of sulfide minerals at high concentrations of solids: a review

Bio-oxidation has proved to be a viable process for the oxidative pretreatment of refractory gold-bearing sulfides. Generally, the oxidation rate is maximal at 20% solids for high sulfide content materials [ca. 30% sulfur]. Low grade ores [1% sulfur] have been successfully oxidized at 55% solids, indicating a link between the sulfide grade of the material and the optimal solids concentration for operation. Concentrations of high solids have been reported to lower oxidation rates, increase lag times, and decrease the ultimate extent of oxidation. This review discusses the various factors that have been proposed as causes of these phenomena. The factors include oxygen and carbon dioxide availability, low bacteria-solids ratio; mechanical damage or inhibition of the bacteria, inhibition of bacterial attachment, and the buildup of toxic leach products or other detrimental substances such as some flotation reagents. (c) 1993 John Wiley & Sons, Inc.     

Factors affecting food utilization by a leaf shredding aquatic insect: leaf species and conditioning time

Gravimetric feeding studies were used to examine the feeding strategy of Pteronarcys proteus (Plecoptera) using unconditioned, 1 month conditioned, and 2 month conditioned deciduous leaves of four species (white oak, red maple, black locust, dogwood). Assimilation efficiencies of Pteronarcys nymphs feeding on unconditioned and conditioned leaf material ranged from 13.4 to 21.9% AFDW of leaf material indicating that Pteronarcys was able to digest and assimilate leaf material. Assimilation efficiencies did not change as leaf material conditioned which suggests that assimilation efficiency does not accurately reflect changes in detrital food quality. However, as leaves conditioned, the ingestion rate of Pteronarcys nymphs accelerated. Rates at which dogwood and locust leaves were ingested peaked after 1 month, then declined with a second month of conditioning. Rates at which maple and oak leaves were ingested increased significantly with 2 months of conditioning. Assimilation rates of Pteronarcys nymphs varied in a pattern similar to ingestion rates. This reflects the importance of ingestion rate in the feeding response of Pteronarcys .     

寒温带湿地火后植被恢复的影响因子

寒温带湿地在维护区域生态平衡方面发挥着重要作用.火是湿地的重要干扰因子.重度火烧会导致湿地生态功能明显退化.火后植被恢复,特别是火后早期植被的恢复是生态系统功能恢复的前提和基础.本文对火后湿地植被恢复影响因子的国内外研究进展进行了综述.寒温带湿地火后植被恢复受到火强度、火面积、火前植被类型、物种更新特性、立地条件等多因子的制约.寒温带湿地火后恢复的长期监测、植被恢复的关键影响因子、冻土层在植被恢复过程中的作用、植被恢复的理论与技术将是今后研究的重要方向.     

土壤有益细菌在植物根际竞争定殖的影响因素

在土壤有益微生物应用于生物肥料、生物杀虫剂、植物生长刺激剂和生物处理剂的过程中,根际定殖具有重要作用。细菌在植物根际定殖是一个比较复杂的过程,影响定殖能力的因素也是复杂多样的。本文综述了参与根部竞争定殖的生物因素,包括受细菌遗传控制的某些特性如鞭毛/运动性、趋化性、多糖、位点特异重组酶/菌落阶段变异、NADH脱氢酶,植物根的分泌物和植物种类等;影响微生物根际定殖的非生物因素如土壤类型、土壤特性和土壤温度等,探讨了影响微生物根际定殖的主要研究方向。     

Factors affecting pectate lyase activity during membrane filtration

Summary This paper presents problems encountered during ultrafiltration of pectate lyase (EC 4.2.2.2) of Erwinia chrysanthemi. Membrane adsorption was related to the chemical nature and charge of the membrane polymer. Simple pre-treatment such as coating with a lysine solution greatly improved recovery efficiency.     

A review of methodological issues affecting LCA of novel food products

Background, aim, and scope  

Life cycle assessment (LCA) was initially developed to answer questions about the environmental impact of available products and services, implying that the product system under study was possible to investigate in detail; however, if new products or processes are to be evaluated, several complications occur. So, this paper aims to review the methodological issues that need careful attention when LCA is used for evaluating novel products, processes, or production from an environmental standpoint, as well as to draw some recommendations related to the best approach when dealing with them.     

Feeding inhibitors and food preference in chewing phytophagous insects

Experiments carried out on chewing phytophagous insects showed that both the slightly and the more highly specialized species are very sensitive to deterrents, but it seems that narrower host specialization is connected with greater sensitivity of the chemoreceptors to feeding inhibitors. As the chemosensory influence of specific phagostimulants can be simulated by other substances, it seems that the sensitivity to deterrents is more important in determining the host range, than the adaptation to specific phagostimulants. Thus the evolution of oligophagy is mainly due to the specialization of chemoreceptors to deterrents. It is suggested that there is a fundamental difference in the function of chemoreceptors reacting upon phagostimulants, and upon deterrents, respectively. The narrow negative specialization to deterrent factors makes possible the use of feeding inhibitors for plant protection purposes.

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Zusammenfassung In letzter Zeit wurde von verschiedenen Verfassern die Bedeutung vergällend wirkender Stoffe für die Nahrungsspezialisation beissender phytophager Insekten betont. Die Häufigkeit des Vorkommens solcher Stoffe im Pflanzenreich, bezogen auf eine Insektenart, war jedoch nur in wenigen Fällen bekannt. Um weitere diesbezügliche Angaben zu erhalten, wurden Versuche mit Hilfe des Blattscheiben-Tests und des Sandwich-Tests an verschieden stark spezialisierten Insektenarten durchgeführt.Es zeigte sich, dass sowohl bei den weniger als auch bei den stärker spezialisierten Arten die überwiegende Mehrzahl der nicht oder nur mässig verzehrbaren Pflanzenarten Vergällungsstoffe enthält. Mit steigender Nahrungsspezialisation ist aber auch eine gewisse Tendenz der Zunahme an Empfindlichkeit gegen Vergällungsstoffe zu verzeichnen. Es scheint also, dass je enger die Spezialisation der Chemorezeptoren auf Fraßstoffe ist, umso enger die negative Spezialisation vermutlich anderer Rezeptoren gegen Inhibitorstoffe ist.Da die Reizwirkung der in den Hauptwirtspflanzen eines oligophagen Insekts enthaltenen spezifischen Frassstoffe auch durch gewisse andere, in nicht verwandten Pflanzen vorkommenden Stoffe ausgelöst werden kann, muss die negative Spezialisation der Rezeptoren gegen Inhibitoren als der wichtigere Faktor der Nahrungsspezialisation betrachtet werden. Es ist also anzunehmen, dass die Evolution der Nahrungsspezialisation im wesentlichen durch letztere Art der Rezeptorenspezialisation bedingt ist.Die Tatsache, dass Stoffe verschiedenster chemischer Beschaffenheit vergällend wirken können, während als Frassstoffe nur gewisse Gruppen von Verbindungen in Betracht kommen, weist darauf hin, dass zwischen den auf Frassinhibitoren und den auf Frasstoffe ansprechenden Chemorezeptoren ein grundlegender funktioneller Unterschied besteht.Die enge negative Spezialisation gegen Vergällungsstoffe ermöglicht die Anwendung derselben gegen beissende Insekten, wie es im Falle des Kartoffelkäfers bereits bewiesen wurde. Diese Möglichkeit ist desto bemerkenswerter, als sie den Weg für die Entwicklung hochspezifischer Pflanzenschutzverfahren eröffnet.

     

Factors affecting protein synthesis during biotin deficiency inAspergillus nidulans

Biotin deficiency in Aspergillus nidulans resulted in a 70% increase of the protein content and increased levels of free and bound aspartate, glutamate, serine, leucine and methionine. Likewise, the activities of NADP+ glutamate dehydrogenase, NAD+ gluatmate dehydrogenase, aspartate aminotransferase and alanine aminotransferase were significantly increased. The total RNA content increased while the DNA content was unaffected. The rRNA/tRNA ratio remained higher in biotin-deficient cells. Supplementation of glutamate, aspartate, serine, leucine and methionine to the culture medium raised the rRNA/tRNA ratio, and the difference observed in the qualitative and the quantitative patterns of protein and dry cell mass between normal and biotin-deficient cultures was abolished.     

Factors affecting detectability of river otters during sign surveys

Sign surveys are commonly used to study and monitor wildlife species but may be flawed when surveys are conducted only once and cover short distances, which can lead to a lack of accountability for false absences. Multiple observers surveyed for river otter (Lontra canadensis) scat and tracks along stream and reservoir shorelines at 110 randomly selected sites in eastern Kansas from January to April 2008 and 2009 to determine if detection probability differed among substrates, sign types, observers, survey lengths, and near access points. We estimated detection probabilities (p) of river otters using occupancy models in Program PRESENCE. Mean detection probability for a 400-m survey was highest in mud substrates (p = 0.60) and lowest in snow (p = 0.18) and leaf litter substrates (p = 0.27). Scat had a higher detection probability (p = 0.53) than tracks (p = 0.18), and experienced observers had higher detection probabilities (p > 0.71) than novice observers (p < 0.55). Detection probabilities increased almost 3-fold as survey length increased from 200 m to 1,000 m, and otter sign was not concentrated near access points. After accounting for imperfect detection, our estimates of otter site occupancy based on a 400-m survey increased >3-fold, providing further evidence of the potential negative bias that can occur in estimates from sign surveys when imperfect detection is not addressed. Our study identifies areas for improvement in sign survey methodologies and results are applicable for sign surveys commonly used for many species across a range of habitats. © 2010 The Wildlife Society     

Factors affecting cell viability during bisection of bovine embryos

The aim of this study was to investigate the effects of temperature, cytochalasin B, sucrose, cell number and developmental stage of embryos on cell loss and cell lysis during embryo splitting. Day-7 morulae and blastocysts were bisected using a metal blade. In Experiment 1, splitting of embryos in control medium (PBS + 10% fetal calf serum) was compared with splitting in the presence of 7.5 mul/ml cytochalasin B. In Experiment 2, the control medium was compared with medium supplemented with 200 mM sucrose. In Experiment 3, the control medium was compared with medium supplemented with sucrose and cytochalasin B. Cell viability was measured by staining nuclei of embryos with Hoechst 33258 and propidium iodide. Cells with nuclei exhibiting pink fluorescence were considered lysed, while blue fluorescence was considered an indication of viable cells. Cells disaggregated during splitting were classified as extruded cells. An effect of the developmental stage was observed in the pooled data from the control groups of the 3 experiments, with a higher proportion of viable cells in bisected morulae compared with bisected blastocysts (77.6 vs 70.0%; P = 0.003). However, as there was no effect of cell number (P = 0.85), the influence of the developmental stage can be contributed to morphological changes rather than to increase of cells associated with this change. In Experiment 1, the cytochalasin B-treated embryos contained a higher percentage of viable cells than the control embryos after removal of the developmental stage effect (P < 0.01). In Experiment 2, no effect on sucrose could be observed. In Experiment 3, the combined use of sucrose and cytochalasin B tended to increase the proportion of cells surviving bisection, but this difference was not significant. In Experiment 1, there was a correlation between viable cells and temperature during splitting (r = 0.42, P = 0.05; temperature range 8.1 degrees C to 15.6 degrees C). No correlation was found in any other group in any of the experiments, nor in the pooled data from the control groups in the 3 experiments.     

Factors affecting the increase of R plasmids during hospitalization

The incidence of the TEM -lactamases among 3,010 Gram-negative rods isolated from 670 anorectal swabs was determined by immunological tests. The results from 44 persons without hospital contact were compared with results from 242 hospitalized patients and 30 nurses working in the hospital. The TEM -lactamase has been found in 10% of the strains isolated from the control group and from patients on day 0 and in 20% of the strains isolated from nurses. On day 10, the number of TEM strains had risen to 15% in hospitalized patients but remained stable in the control group. The increase of TEM-producing strains is significantly favored in patients receiving antimicrobial agents, but also occurred in patients without antibiotic therapy. Patients in surgery acquired TEM-producing strain as much as patients in internal medicine. Older patients (35 years) acquired more TEM-producing strains even if they did not receive antibiotics. The factors influencing the prevalence of TEM-type -lactamase were the duration of hospitalization and the age of the patient.     

Factors affecting ovary activation in honey bee workers: a meta-analysis

A conspicuous feature of honey bee social biology is the division of labour between reproductive queens and functionally sterile workers. However, the sterility of workers is conditional and sensitive to genetic and environmental context. Despite this understanding, we do not yet know how effective differences in genotype versus differences in colony environment are for generating variation in levels of ovary activation in a population of workers. We therefore performed a field study and meta-analysis to estimate the standardized effect size g of broad ‘environmental’ and ‘genetic’ manipulations on worker ovary scores. Despite considerable differences in methodology and treatment among published studies, we report that both genetic and environmental manipulations were effective at generating differences in ovary phenotype between groups of worker bees. Our analysis found that environmental treatments, such as differences in pheromones and diet, had a larger mean effect on worker ovary activation scores than have genetic factors such as patriline or strain (g = 0.54 vs. 0.39). We conclude by discussing the biological significance of environmentally sensitive sterility in honey bee societies.     

Factors affecting floral herbivory in a limestone grassland

The amount of herbivore damage to the petals of 41 species of herbaceous plant was surveyed from April to September in a limestone grassland in central England. Damage was recorded as the percentage of the petal area removed. Most damage was caused by invertebrates, particularly slugs. The amount of invertebrate damage differed significantly between plant species and with time of year. The mean damage across all species was only 2 %, ranging from an average of 0 % in Galium sterneri to 8 % in Primula vulgaris. In most species, less than a quarter of flowers received any damage, so those that were damaged were often severely affected. Species flowering early or late in the season received more damage, possibly because of greater slug activity. Hypotheses to explain the inter-specific variation in the amount of herbivory were examined by testing for correlations with a range of plant variables. No correlations with flower-stem length, flower-stem thickness or the longevity of flowers were apparent. The amount of petal damage correlated strongly with flower size and petal thickness. This appeared to result from the prevalence of large-flowered species early and late in the season rather than from a preference for flower size and petal thickness per se. The evolutionary significance of floral herbivory is discussed.