Factors affecting hemolysin production byVibrio vulnificus

Factors affecting the hemolytic activity ofVibrio vulnificus cultures supernatant fluids against sheep erythrocytes were studied in order to optimize conditions and develop an assay system to assess the pathogenic potential of marineV. vulnificus strains. The heat-labile hemolysin produced during logarithmic growth ofV. vulnificus was produced optimally in heart infusion broth (HIB). Lesser amounts of hemolysin were produced in brain-heart infusion and tryptic soy broths. Hemolytic activity of HIB cultures decreased with increasing NaCl concentrations. Higher NaCl concentrations were found to affect hemolysin production but not its activity. The assay system described herein is a simple and rapid method that is being applied to the study of the pathogenic potential ofV. vulnificus strains from marine environments.     

Factors affecting pheromone production in beetles

Pheromone production and/or release by beetles is coordinated with a variety of behavioral, physiological, and environmental factors. To data, two basic mechanisms for the regulation of pheromone biosynthesis in beetles have been proposed. Pheromone biosynthesis may simply be dependent on the availability of biosynthetic precursors. Alternatively, certain stimuli or events may trigger pheromone biosynthesis via juvenile hormone (JH) action. JH may either act directly at the site of pheromone biosynthesis to enhance pheromone production or may act indirectly, through a brain hormone (which might be related to the pheromone biosynthesis activating neuropeptide) or through effects on antennal sensory response. Knowledge of the regulation of the initiation and termination of pheromone biosynthesis is reviewed. Mechanisms by which pheromone stereochemistry is controlled are also discussed. This is an important aspect of pheromone production in Coleoptera, since slight changes in the stereochemistry can completely alter the activity of the molecule. © 1994 Wiley-Liss, Inc.     

同源四倍体水稻原种制备及影响因素分析

本研究已将从全国各地征集的50份水稻优良种质资源(2n=2x=24)诱变为同源四倍体水稻原种。本文讨论不同处理日期、不同秋水仙碱浓度和处理时间、以及不同品种的抗药性等因素对加倍成功率的影响,结果表明:①不同日期处理水稻幼芽,其加倍成功率不同,4月6日～15日加倍效果最好,加倍成功率达19.4%。②不同浓度秋水仙碱和处理时间其加倍成功率存在一定的差别。0.1%秋水仙碱处理48h 和0.2%处理24h 为佳,其芽恢复率超过58%,加倍成功率超过16%。③不同水稻品种抗药性不同。在所加倍的50个水稻品种中,中作9025抗药性最强,芽恢复率达92.4%,加倍成功率38.7%。盐州14抗药性最差,芽恢复率仅为10.6%。     

Factors affecting success of embryo collection and transfer in a transgenic goat program

During a goat transgenic program that took place in Israel from July 1995 to February 1996, Saanen (n = 343) and Nubian x Damascus (n = 378) crossbred goats of mixed ages were used as donors (n = 433) and recipients (n = 288). The effects of season, age, number of surgical procedures, previous hormonal treatments and ovulation rate on the number of microinjectable embryos collected were studied. Likewise, the effects of these parameters on the pregnancy rate as well as the number of embryos transplanted, endogenous progesterone concentrations and exogenous progesterone supplementation were studied in recipient does. Following superovulation with ovine follicle stimulating hormone, 85% of the does responded with 13.6 +/- 5.7 (mean +/- S D) ovulations/doe. Age, month and number of previous hormonal treatments significantly affected the ovulation rate. The average recovery rate was 70%, and it was affected only by the ovulation rate. Pronuclei were visualized in about 30% of the flushed embryos (including unfertilized ova), and those were microinjected with human serum albumin gene construct. About 68% of the injected embryos underwent at least one division during an overnight incubation, and those embryos were transferred, giving about 2.0 transferred embryos per ovulated donor. Of the recipients, 86% responded following synchronization with 3.1 +/- 1.6 (mean +/- S D) ovulations per doe. Breed and month had a significant effect on the ovulation rate. Two or three microinjected embryos were transferred to each recipient, resulting in more than a 40% pregnancy rate during September to November. Lower pregnancy rates were obtained before and after that period. By monitoring plasma progesterone concentrations in the recipients it was found that progesterone concentration was correlated with the ovulation rate. However, the pregnancy rate was not affected by progesterone concentration. During January and February, 30 to 50% of the recipients failed to develop functional corpora lutea (CL) following embryo transfer, which explained the lower pregnancy rate in those months. Of the 86 kids born 4 were transgenic.     

Factors affecting ultrasound production in infant rodents

Studies on the motivation for the production of ultrasound in rodents revealed that two principal factors influence this phenomenon in the infants. These have already been reported in full for white mice and partially for Wistar rats and Golden hamsters. The present paper completes the report on all five species that were investigated and makes a general assessment of the findings.     

Factors affecting progeny production of Anaphes iole

Anaphes iole Girault(Hymenoptera: Mymaridae) is a native, solitaryegg parasitoid of Lygus spp.(Heteroptera: Miridae) in North America. Current research is considering factors thatmay optimize the in-vivo rearing of A.iole using Lygus hesperus Knight(Heteroptera: Miridae) as host. The effects ofhost density, day of oviposition and foodpresence, parasitoid age and mate presence onproduction of A. iole progeny weredetermined in this study. After exposingindividual parasitoids to host patches for 24h, the percentage of hosts containing a latestage A. iole pupa wassignificantly greater at a moderate hostdensity (41–70 eggs per patch) than at a lowdensity (10–40 eggs). But, no differenceswere detected between moderate and high density(71–100 eggs) or between high and low densitytreatments. More adult progeny were generatedby females (of variable age; 0–2 d old) onthe first day of oviposition rather than thesecond day, regardless of food presence. Progeny sex ratio was decidedly male-biased onthe second day. Female age (0 d vs 1 d old)had a marginal effect on production in 24 h; 0d old females tended to generate more adultprogeny than 1 d old females. Overall, thisresearch suggests that exposing newly-emerged,unfed, mated A. iole females to amoderate to high host density for 1 to 2 dcould lead to time-efficient production ofadult progeny in an in-vivo rearing system.     

Factors affecting lipase production in Syncephalastrum racemosum

Syncephalastrum racemosum grown as a static culture showed maximum lipase production at 30°C in 2d at pH 8.0. When the medium was supplemented with fructose, maximum production of lipase per unit of growth was achieved, followed by raffinose, sucrose, ribose, galactose, maltose, lactose, mannitol and glucose. Amongst the nitrogen sources tested, corn steep liquor at 8% (v/v) produced maximum enzyme; there was evidence of catabolite repression by glucose when groundnut protein, soybean meal, milk casein or wheat bran were the sources of nitrogen. Calcium, potassium and sodium citrates, each at 0.1% (w/v), increased the yield of lipase.     

Factors affecting quality of informed consent.

OBJECTIVE--To examine the factors influencing quality of informed consent. DESIGN--Prospective study comprising interviews with patients and patients'' completing standard questionnaires. SETTING--Academic surgical unit of large teaching hospital. PATIENTS--265 patients undergoing intrathoracic, intraperitoneal, and vascular surgical procedures. Of these patients, 192 have been followed up for six months. MAIN OUTCOME MEASURES--Patients'' recall of information at various points in the study; this score was compared by age, provision of written information, cognitive function, intelligence quotient (IQ), mood state and personality traits, and health locus of control. RESULTS--The patients were best informed immediately after signing the consent form and from then on recall of information deteriorated. A total of 172/250 (69%) patients admitted to not reading the consent form before signing it. Old age adversely affected recall of information at all assessment points. Impaired cognitive function reduced information recall only during the stay in hospital. Patients with above average IQs handled information better than those with a lower IQ except immediately after the signing of consent forms. Patients with an internal locus of health control (that is, those who believed their health to be in their own control) were better informed than those with an external locus of health control. Operation information cards improved recall only on the day of discharge. CONCLUSION--Elderly patients and patients with below average IQ, impaired cognitive functions, and an external locus of control have poor information recall. Written information may be more useful if given before admission to hospital.     

Factors affecting placental traits and relationships of placental traits with neonatal behaviour in goat

The relationships between placental characteristics and litter weight, factors affecting these characteristics, and the relationship between these characteristics and neonatal behaviour of goat kids were investigated in this study. The study was carried out over three consecutive years and animal material consisted of total 152 Turkish Saanen goats and their 230 kids. The results of the study demonstrated that there were positive correlations between litter weight (LW), cotyledon number (CN), placental weight (PW) (r=0.64 and 0.76, P<0.01), but there was negative correlation between LW and cotyledon density (CD) (r=-0.42, P<0.01). CD was negatively correlated with PW (r=-0.61, P<0.01). CN and PW were influenced by the parity of doe, birth type-sex combination, buck within years and year of the study. On the other hand, parity and birth type-sex combination had no effect on PE (P>0.05), but buck within year affected placental efficiency (P<0.01). CD was only influenced by the parity of doe (P<0.01). Duration of birth (D) was not significantly related with CD, but if CD declined, it prolonged (r=-0.23, P>0.05). There were strong relationships between CD and birth-to-standing (B-St), and CD and birth-to-suckling (B-Su) (r=-0.42 and -0.51, P=0.01 and P<0.01).The results of the present study have shown similarities to the findings of the studies in sheep. Further studies are required to investigate the basis of the relationship between CD and neonatal behaviour.     

Factors affecting recovery and quality of oocytes for bovine embryo production in vitro using ovum pick-up technology

In Experiment 1, different vacuum pressures (30, 50, 70 and 90 mm Hg) were used to aspirate 4156 bovine follicles in vitro, to assess their effect on flow rate and the recovery, morphology and blastocyst formation of the recovered oocytes. Cumulus oocyte complexes (COCs) were classified according to the morphology of the cumulus cells. Data were analyzed using Chi Square analysis. Overall recovery rate declined as the aspiration pressure increased above 50 mm Hg (P<0.05). The recovery rate of Grade 1 oocytes decreased significantly (P<0.05) as the vacuum pressure increased with a corresponding increase in the number of denuded oocytes recovered (P<0.05). The blastocyst yield, expressed as a percentage of recovered COCs decreased significantly as the aspiration pressure increased beyond 50 mm Hg (P<0.05). In Experiment 2, the holding media (hepes- or bicarbonate-buffered TCM 199) and holding time (1 h or 5 h) did not affect the blastocyst formation of the oocytes (P>0.05). In Experiment 3, it was found that individual culture of the oocyte during fertilization or culture had a detrimental effect on the oocytes blastocyst formation (8.8% to 16% blastocyst yield on Day 8) when compared to control (31.3%). In Experiment 4, groups of 5, 10 and 25 oocytes were compared with singly cultured oocytes. There were no significant differences (P<0.05) in the blastocyst formation rate among groups of 5, 10, or 25 oocytes, but there was a significant difference between oocytes processed in groups and those processed individually. In Experiment 5, when groups of 10 oocytes were cultured in different drop sizes, there was no significant difference in cleavage rates between oocytes cultured in 100 microL (85.0%, n = 280) and in 10 microL (86.8%, n = 280) of media, but culture in 50 microL (79.3%, n = 280) resulted in cleavage rates significantly lower (P<0.05) than culture in 10 microL drops. There was no significant difference in the blastocyst formation. However there was a significant difference (P<0.05) in cell numbers of Day 8 blastocvsts, with oocytes cultured in 100 microL drops having significantly lower cell counts than oocytes cultured in 50 or 10 microL drops.     

Impacts of production conditions on goat milk vitamin,carotenoid contents and colour indices

The content, composition and variation of vitamin compounds in goat milk have been little studied. An experimental design was based on 28 commercial farms, selected considering the main feeding system (based on main forage and especially pasture access), goat breed (Alpine vs Saanen) and reproductive management (seasonal reproduction), in the main French goat milk production area. Each farm received two visits (spring and autumn) that included a survey on milk production conditions and bulk milk sampling. Milk vitamins (A, E, B₂, B₆, B₉, B₁₂) and carotenoid concentrations plus colour indices were evaluated. A stepwise approach determined the variables of milk production conditions that significantly altered milk indicators. The main forage in the diet was the major factor altering goat milk vitamin and carotenoid concentrations and colour indices. Bulk milk from goats eating fresh grass as forage was richer in α-tocopherol (+64%), pyridoxal (+35%) and total vitamin B₆ (+31%), and b* index (characterising milk yellowness in the CIELAB colour space) was also higher (+12%) than in milk from goats eating conserved forages. In milk from goats eating fresh grass, concentrations of pyridoxamine, lutein and total carotenoids were higher than in milk of goats fed corn silage (+24, +118 and +101%, respectively), and retinol and α-tocopherol concentrations were higher than in milk of goats fed partially dehydrated grass (+45 and +55%). Vitamin B₂ concentration was higher in milk of goats eating fresh grass than in milk of goats fed hay or corn silage as forage (+10%). However, bulk milk when goats had access to fresh grass was significantly poorer in vitamin B₁₂ than when fed corn silage (?46%) and in γ-tocopherol (?31%) than when fed conserved forage. Alpine goats produced milk with higher vitamin B₂ and folate concentrations than Saanen goats (+18 and +14%, respectively). Additionally, the milk colour index that discriminates milks based on their yellow pigment contents was 7% higher in milk from Alpine than Saanen herds, but milk from Saanen goats was richer in lutein (+46%). Goat milks were richer in vitamins B₂ and B₁₂ and folates, but poorer in vitamin B₆ in autumn than in spring (+12, +133, +15 and ?13%, respectively). This work highlights that goat milk vitamin and carotenoid concentrations and colour indices vary mainly according to the main forage of the diet and secondly according to the breed and season.     

Factors affecting in vitro microrhizome production in turmeric

In vitro microrhizome production was obtained in turmeric (Curcuma longa Linn.). Freshly sprouted buds with small rhizome portions excised from stored mature rhizomes were cultured on semi-solid culture initiation medium –- MS basal medium + 0.88 M BAP (6-benzylaminopurine) + 0.92 M kinetin + 5% coconut water + 2% sucrose + 0.5% agar –- resulting in bud elongation. Multiple shoots were produced from these elongated buds by culturing in liquid shoot multiplication medium –- MS basal medium + 2.2 M BAP + 0.92 M kinetin + 5% coconut water + 2% sucrose –- at 25±1°C and 16-h light (at 11.7 mol m^–2 s^–1)/8-h dark cycles. Clumps of four to five multiple shoots/single shoots were used in various experiments. Cultures were incubated in the dark at 25±1°C. Half strength MS basal medium supplemented with 80 g l^–1 sucrose was found to be optimal for microrhizome production. Cytokinin BAP had an inhibitory effect on microrhizome production. At the highest concentration of BAP tried (35.2 M) microrhizome production was totally inhibited. Microrhizome production depended on the size of the multiple shoots used. Microrhizomes produced were of a wide range in size (0.1–2.0 g) and, readily regenerated when isolated and cultured in vitro on culture initiation medium or shoot multiplication medium. Under in vivo conditions, small (0.1–0.4 g), medium (0.41–0.8 g) and big (>0.81 g) microrhizomes regenerated. Plantlets developed from big microrhizomes grew faster.     

Factors affecting natural antiallotype antibody production in rabbits

Since not all rabbits that have receivedb locus-incompatible antigens from the mother respond with natural antiallotype antibody, various factors were studied to determine their role in the expression or nonexpression of antibody production in the individual rabbit. It was found that the mother-offspring allotype relationship is important in determining the probability that a given individual will respond to maternally derived allotype differences, and that the ability to respond is under genetic control. The genetic basis appears to be polygenie with the response status of a given animal determined by a threshold of response-positive genes needed for response. A greater number of response-positive genes seems to be required if there is an antigenic relationship between the incompatibleb-locus antigen from the mother and the individual's ownb-locus antigens.Abbreviations used in this paper are as follows BDB bis-diazotized benzidine - _c ² chi-square corrected for continuity - HPA high probability antibody - LPA low probability antibody - HPA(+) or LPA(+) animal produced the natural antiallotype antibody designated - HPA(–) or LPA(–) animal did not produce the natural antiallotype antibody designated, even though it had the potential to do so     

Factors affecting the development of two fermented milk products in Zimbabwe

Summary The effect of container, of pasteurization and of using starter cultures were studied with respect to lactic acid production, lactic acid bacterial counts, total microbial counts and the acceptability of two traditionally- and industrially-fermented milk products of Zimbabwe. Earthenware pots were better containers for the fermentation of pasteurized milk than glass containers. Pasteurization decreased both lactic acid bacteria counts and lactic acid production in traditionally-fermented milk.Lacto (an industrially-fermented milk product) was less acceptable to the panelists than unpasteurized milk fermented either in glass containers or in earthenware pots.

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Facteurs affectant le développement de deux produits fermentés du lait au Zimbabwe

Résumé On étudie l'effet du conteneur de pasteurisation et de l'emploi de pieds de cuvesur la production d'acide lactique, sur l'énumération des bactéries lactiques, sur l'énumération des germes totaux, et sur l'acceptabilité de deux produits du lait du Zimbabwe, l'un fermenté de manière traditionnelle, l'autre fermenté industriellement. Des pots en terre se révèlent meilleurs conteneurs pour la fermentation du lait pasteurisé que des conteneurs en verre. La pasteurisation réduit tant l'énumération de bactéries lactiques que la production d'acide lactique dans le lait fermenté de manière traditionnelle. Des goûteurs trouvent leLacto (un produit du lait fermenté industriellement) moins bien acceptable que le lait non pasteurisé qu'il soit fermenté en conteneurs en verre ou en pots de terre.