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At least 883 records · Page 49Linked to original sources
PubMed2005

The impact of fine sediment accumulation on the survival of incubating salmon progeny: implications for sediment management.

This paper draws on results from a recent research programme on the impact of fine sediment transport through catchments to present a case for the development of new approaches to improving the quality of salmonid spawning and incubation habitats. To aid the development of these programmes, this paper summarises the mechanisms by which fine sediment accumulation influences the availability of oxygen (O2) to incubating salmon embryos. The results of the investigation indicate that incubation success is inhibited by: (i) the impact of fine sediment accumulation on gravel permeability and, subsequently, the rate of passage of oxygenated water through the incubation environment; (ii) reduced intragravel O2 concentrations that occur when O2 consuming material infiltrates spawning and incubation gravels; and (iii) the impact of fine particles (clay) on the exchange of O2 across the egg membrane. It is concluded that current granular measures of spawning and incubation habitat quality do not satisfactorily describe the complexity of factors influencing incubation success. Furthermore, an assessment of the trends in fine sediment infiltration indicates that only a small proportion of the total suspended sediment load infiltrates spawning and incubation gravels. This casts doubt over the ability of current catchment-based land use management strategies to adequately reduce fine sediment inputs.

Animals↗
PubMedDate not supplied

Comparative studies on the growth and reproductive performances of Rhodnius prolixus reared on different blood sources.

Host blood source was found to affect both the development and the reproductive performance of Rhodnius prolixus. The insects were reared on citrated human, rabbit, chicken, sheep and horse blood sources, through a membrane feeder, during an entire life cycle, from eggs to adults. Development and reproduction in terms of the number of unfed insects, number of moulting, mortality intermoulting period, number of egg/female, conversion of blood into egg (mg meal/egg) and percentage of hatch as effective physiological parameters were investigated. Our results showed that human or rabbit blood meals were more nutritionally efficient than the other blood samples used because (i) the insects developed faster, presented low mortality and about 80% of them reached the adult stage; and (ii) females oviposited an average of at least 100% more eggs. The inefficiency of chicken and horse blood sources as diets for R. prolixus was manifested in (i) a decrease of the amount of ingested blood and (ii) only a reasonable nutritional quality. The inadequacy of sheep blood was observed by a mortality extremely high, poor moulting response and drastic reduction in egg production.

Animals↗
PubMed2003

Mothers influence offspring body size through post-oviposition maternal effects in the redbacked salamander, Plethodon cinereus.

In the terrestrial salamander (Plethodon cinereus), previous work has shown that mother's body size is positively correlated to offspring size at the time of hatching even after controlling for the effects of egg size. This study was designed to determine whether maternal body size affects offspring size via pre-oviposition factors (e.g., yolk quality, jelly coat composition, or maternal genes) or post-oviposition factors (e.g., parental care behaviors, parental modification of environment). Gravid females were captured and induced to lay eggs in experimental chambers in which the environment was standardized. Fifteen clutches were exchanged, or cross-fostered, between female pairs differing in body size. Ten females whose eggs were taken away and then returned served as controls for the crossing treatment. Foster mothers did not significantly differ from control mothers in the time spent with eggs, body position, or number of egg movements during brooding. Average egg mass measured midway through development was not significantly correlated to the body size of either the genetic or foster mother, but was correlated to pre-oviposition oocyte size. At hatching, offspring body length was positively correlated to egg size and the foster mother's body size. This correlation suggests that in P. cinereus post-oviposition maternal effects have a greater impact on offspring size than other maternal factors incorporated into the egg prior to oviposition. While our study showed that larger mothers moved their eggs less often and tended to spend more time in contact with their eggs, further work needs to be done to identify the specific mechanisms through which larger mothers influence the body size of their offspring. This is the first experimental demonstration of post-oviposition maternal effects for any amphibian with parental care.

Animals↗
PubMed1999

Dose-morality and large-scale studies for controlling codling moth (Lepidoptera: Tortricidae) eggs on 'd'Agen' plums by using methyl bromide.

Codling moth, Cydia pomonella (L.), eggs on 'd'Agen' cultivar of plums, Prunus salicina Lindl., were treated with methyl bromide to determine if a quarantine treatment could be developed so that the plums could be exported to Japan from the United States. Small-scale tests consisted of treating codling moth eggs on plums with various doses of methyl bromide at 20 degrees C for 2 h. Small-scale tests showed that 0- to 24-h-old eggs of codling moth on the plums were controlled by doses > 22.5 g/m3. Because testing showed that 48 g/m3 had no adverse effect on the quality of plums, this dose was chosen for large-scale testing to establish the quarantine dose. Large-scale tests consisted of treating plums at 18.5 degrees C for 2 h using methyl bromide at a dose of 48 mg/liter. Large-scale tests showed that the dose of 48 g/m3 killed all 0- to 24-h-old codling moth eggs exposed on plums in packing cartons without affecting the quality of the plums.

Animals↗
PubMed2002

Measuring the eggshell strength of 6 different genetic strains of laying hens: techniques and comparisons.

1. Eggshell quality was compared in 6 different strains of laying hens. Three strains were commercial; the three others were experimental. 2. Four different variables describing the strength of eggshells were investigated. Three of them were the classical ones eggshell thickness, shell stiffness measured during quasi-static compression and breaking force. Dynamic stiffness, introduced by Coucke (Ph.D. Thesis, KU Leuven, 1998), was the 4th. The fact that this measurement is dynamic could be helpful in genetic selection for eggshell breakage, because forces applied to the egg in practice are dynamic, rather than static. 3. Hisex White hens produce eggs with the strongest eggshell, in terms of all 4 eggshell variables. However, their shell quality in terms of breaking force did not remain constant over the laying period, unlike 4 other strains. 4. All strains showed a decline in quasi-static stiffness over time. 5. The eggshell thickness of three strains showed a decline over time. 6. Dynamic stiffness remained constant or improved in all strain. 7. All variables describing the mechanical eggshell strength gave different information.

Animals↗
PubMed2001

Impact of doramectin treatment at the time of feedlot entry on the productivity of yearling steers with natural nematode infections.

OBJECTIVE: To measure the reduction in fecal nematode egg counts and productivity impact of treatment of yearling steers with doramectin at entry into the feedlot, compared with control steers treated only with fenthion. ANIMALS: 6,096 crossbred yearling steers with a mean (+/- SD) body weight of 377.0 (+/- 37) kg. PROCEDURE: Steers were implanted with zeranol and alternately separated to fill each of 24 pens. Groups of steers within 12 matched pairs of pens were randomly allocated to treatment with doramectin or no treatment with doramectin for internal nematodes. Fecal samples were collected from approximately every twentieth steer from each pen at day 0 and at reimplant (approx day 60). Each steer was weighed on day 0 and at reimplant and then mean body weights of steers per pen were determined at 120 to 140 days after trial initiation. RESULTS: Treatment steers had a significantly lower fecal egg count at reimplant than control steers. Treatment steers had a significantly greater mean daily gain during the study, significantly greater feed consumption, significantly lower feed-to-gain ratio, and significantly better quality carcass grades at slaughter. CONCLUSIONS AND CLINICAL RELEVANCE: Under the conditions of our trial, there was a significant fecal egg count reduction response to doramectin treatment, which resulted in significantly improved productivity. Results of economic analysis of return on investment indicated that even with low egg counts in heavy body weight cattle, nematode egg count reduction with doramectin significantly improved returns.

Anabolic Agents↗
PubMed2006

Slow fertilization of stickleback eggs: the result of sexual conflict?

BACKGROUND: The fertilization success in sperm competition in externally fertilizing fish depends on number and quality of sperm. The time delay between sequential ejaculations may further influence the outcome of sperm competition. Such a time interval can load the raffle over fertilization if fertilization takes place very fast. Short fertilization times are generally assumed for externally fertilizing fish such as the three-spined stickleback (Gasterosteus aculeatus). In this pair-spawning fish, territorial males often try to steal fertilizations in nests of neighbouring males. This sneaking behaviour causes sperm competition. Sneakers will only get a share of paternity when eggs are not fertilized immediately after sperm release. Contrary to males, females may be interested in multiple paternity of their clutch of eggs. There thus may be a sexual conflict over the speed of fertilization. RESULTS: In this study we used two different in vitro fertilization experiments to assess how fast eggs are fertilized in sticklebacks. We show that complete fertilization takes more than 5 min which is atypically long for externally fertilizing fishes. CONCLUSION: This result suggests that the time difference does not imply high costs to the second stickleback male to ejaculate. Slow fertilization (and concomitant prolonged longevity of sperm) may be the result of sexual conflict in which females aimed at complete fertilization and/or multiple paternity.

Animals↗
PubMed1981

An optically clear hypercholesterolemic hypertriglyceridemic quality-control material prepared from animal lipid sources.

A hyperlipidemic control serum can be simple prepared from animal lipid sources. Beta- and pre-beta-lipoproteins containing cholesterol and triglyceride are removed from porcine serum by treatment with dextran sulfate and calcium ions. A triglyceride-rich fraction containing only trace amounts of cholesterol is isolated from chicken egg-yolks. The two fractions are then combined in 40 mmol/L sodium bicarbonate to give the desired values for cholesterol and triglyceride. The preparation is stabilized against surface denaturation during long-term storage at 5 degrees C perhaps for as long as two years, by adding 0.25 g of Triton X-100 surfactant per liter, and against an accidental exposure to short-term freezing by adding 10 g of sucrose per liter. We used this solution as a diluent to reconstitute lyophilized bovine serum. The resulting product, having been prepared from only animal sources, is free of hepatitis-associated constituents, and is remarkably clear, homogeneous, and stable. Results obtained with it are precise.

Animals↗
PubMed2004

Liquid storage of Asian elephant (Elephas maximus) sperm at 4 degrees C.

The Asian elephant (Elephas maximus) population in the wild has been in decline for several decades and breeding in captivity has not been self-sustaining. The use of artificial insemination (AI) can help overcome many of the difficulties associated with breeding elephants in captivity; however, the ability to store semen for extended periods of time is critical to the successful application of AI to elephants. The objective of the present study was to assess the effects of four different semen extenders and the presence of egg yolk on the viability and motility of Asian elephant semen stored at 4 degrees C. High quality ejaculates (n=4) were collected from two Asian elephant bulls by rectal massage. Aliquots of each ejaculate were extended in four different diluents (Beltsville thawing solution (BTS); Tris-citric acid (TCA)/fructose-based; Beltsville F5 (BF5); dextrose-supplemented phosphate-buffered saline (PBS)) with or without egg yolk then cooled and stored at 4 degrees C. The percentages of viable (viability) and motile (motility) sperm were evaluated at 8, 24 and 48 h following collection. The addition of egg yolk significantly reduced the percentage loss in viability from initial collection to 48 h compared to extenders without egg yolk (17.0 +/- 8.2 versus 32.6 +/- 8.9 decline in percent viable sperm in the population, respectively; P<0.05). Extender and egg yolk affected (P<0.005) total motility and percent progressively motile sperm at all evaluation times during incubation. TCA + egg yolk maintained higher (P<0.05) levels of progressive motility compared to other extenders supplemented with egg yolk. These results indicate that Asian elephant semen extended in TCA diluent supplemented with egg yolk can maintain at least 50% viability and motility when stored at 4 degrees C for 48 h.

Animals↗
PubMed1990

The effect of 1 alpha,25-dihydroxyvitamin D3 added to a layer diet containing adequate amounts of vitamin D3 on the performance of layers.

The effect of adding 1 alpha,25-dihydroxyvitamin D3 (calcitriol) to a well-balanced, commercial layer diet containing 1,900 IU vitamin D3/kg on eggshell quality and laying performance of 56-wk-old White Leghorn hens was investigated. After 8 wk of treatment, calcitriol at 1.5 micrograms/kg diet had no discernible effect on egg weight, egg deformation, percentage shell, shell thickness, feed consumption, and egg production. At 3.0 and 4.5 micrograms/kg, feed consumption, feed production, and egg weight were significantly reduced, whereas egg deformation, percentage shell, and shell thickness were not affected. The results show that calcitriol added to a diet already adequately supplemented with vitamin D3 does not improve eggshell quality and may impair laying performance.

Animals↗
PubMedDate not supplied

[Multiparametric description of voice quality for normal male and female voices].

The present study examines the relevance of the voice parameters of two commercially available voice analysis programs (MDVP and EGG Program from Kay Elemetrics) for the acoustic and electroglottographic definition of normal voice profiles for men and women. Vowel productions of 300 adult speakers (150 male and 150 female speakers) without any known voice pathology were analyzed. In a first step, gender-differentiated mean normal voice profiles are presented for each of the two analysis programs. The significant differences between the male and female speakers indicate the necessity for the separate treatment of the two groups. In a second step, a clustering technique differentiates two numerically substantial subgroups within each gender on the basis of the MDVP parameters. The EGG parameters do not achieve the same degree of subgroup differentiation. In a factor analysis, the relative weighting of the MDVP parameters within the factors also indicates their better suitability for normal voice differentiation than the EGG parameters as they are defined at present.

Adolescent↗
PubMed2005

Developmental interaction between suboptimal instars of Spodoptera littoralis (Lepidoptera:Noctuidae) and its parasitoid Microplitis rufiventris (Hymenoptera:Braconidae).

Relative effects of parasitism by Microplitis rufiventris on the development of the third instar Spodoptera littoralis (preferable, optimal host) with the development of penultimate (5th) and last (6th) instars (suboptimal hosts) were investigated. Newly molted 6th instar hosts were more acceptable for parasitization by the wasp female than older hosts. In singly parasitized 3rd instar hosts, 82.0 +/- 3.9% of the parasitoid eggs developed to full-grown instar wasp larvae. However, parasitoid eggs deposited singly in 73.9 +/- 3.3% of 5th and 100% of 6th instar hosts failed to develop. Superparasitization in the 3rd instar hosts reduced the production of pseudoparasitized larvae and, conversely, all parasitized hosts yielded viable parasitoid offspring. In suboptimal hosts, the development interaction between the parasitoid and its host larvae was highly influenced by the age of hosts at parasitism, load of deposited eggs, and other parasitoid factors. The latter factors, e.g., mainly calyx fluid particles, might be involved in establishing parasitoid eggs in the suboptimal hosts. In the last two host instars, superparasitization significantly increased the number of parasitoid larvae successfully reaching their final instar. Variation in host quality, e.g., physiological status, might be attributed, in part, to the partial breakdown of the solitary habit observed in the earlier instars. More parasitoid eggs developed to mature parasitoid larvae in hosts superparasitized as 6th instar than parasitoid eggs laid in 5th instar hosts. Superparasitization significantly lengthened the developmental period of 5th and 6th host instars and inhibited their development to the pupal stage. Studying parasitoid development in suboptimal instars of its habitual host provided physiological insight, as shown here. The results may have implication for biological control and in vitro mass rearing programs with solitary parasitoids.

Age Factors↗
PubMed1997

Protein crystallization in microgravity.

A space experiment involving protein crystallization was conducted in a microgravity environment using the space shuttle "Endeavour" of STS-47, on a 9-day mission from September 12th to 20th in 1992. The crystallization was carried out according to a batch method, and 5 proteins were selected as flight samples for crystallization. Two of these proteins: hen egg-white lysozyme and co-amino acid: pyruvate aminotransferase from Pseudomonas sp. F-126, were obtained as single crystals of good diffraction quality. Since 1992 we have carried out several space experiments for protein crystallization aboard space shuttles and the space station MIR. Our experimental results obtained mainly from hen egg-white lysozyme are described below, focusing on the effects of microgravity on protein crystal growth.

Crystallization↗
PubMed1996

The effect of different levels of vitamin C and cholecalciferol with adequate or marginal levels of dietary calcium on performance and eggshell quality of laying hens.

Three experiments were conducted to determine whether shell quality, bone mineralization, and other production traits could be improved by adding vitamin C (ascorbic acid) to laying hen diets. The period of each experiment was 12 wk. Experiment 1 consisted of a 2 x 2 x 3 factorial design with two levels of Ca (2.8 and 3.8%), two levels of cholecalciferol (vitamin D3; 2,200 and 4,400 IU/kg diet), and three levels of vitamin C (0, 125, and 250 ppm). Experiment 2 consisted of a 2 x 3 x 2 factorial design with two levels of Ca (2.8 and 3.8%), three levels of vitamin D3 (250, 500, and 2,000 IU/kg diet), and two levels of vitamin C (0 and 250 ppm). Experiment 3 consisted of a 2 x 4 factorial design with two sources of vitamin D3 (12.5 micrograms vitamin D3/kg diet or 12.5 micrograms 25-OH-D3/kg diet) and four levels of vitamin C (0, 250, 500, and 1,000 ppm). Calcium level was kept constant at 3.5% for all the diets in Experiment 3. Production performance was not influenced by dietary treatments in Experiment 1. In Experiment 2, feed conversion was improved (P < 0.05) due to increasing the dietary Ca, and egg weight and egg size were increased (P < 0.05) due to adding 250 ppm vitamin C to the diet. In experiment 3, albumen quality was increased by the addition of 1,000 ppm vitamin C to the diet. Egg specific gravity was increased in Experiments 1 and 2 only, due to increasing the Ca level (P < 0.05). In Experiment 2, increasing the Ca level and increasing the vitamin D3 level from 250 to 2,000 ppm reduced (P < 0.05) the number of cracked eggs, but incidence of cracked eggs was increased with the addition of 250 ppm vitamin C to the diet. In Experiment 1, plasma level of 1,25(OH)2D3 was greater (P < 0.05) for hens fed 2.8 than 3.8% Ca, but blood acidbase balance was not influenced by dietary regimens. Bone ash was not influenced by dietary treatments in any of the experiments. The data indicated that a supplemental level of vitamin C had no beneficial effects on shell quality and bone mineralization under the conditions of the current experiments.

Aging↗
PubMed2006

Risk-adjusted rates for potentially avoidable reoperations were computed from routine hospital data.

OBJECTIVES: Reoperations may reflect a suboptimal initial surgical treatment. The study aimed to develop a screening algorithm for those potentially avoidable, using only routinely collected hospital data and a prediction model to adjust rates for case-mix. STUDY DESIGN AND SETTING: Data of a 3-year random sample of 7,370 therapeutic operations on inpatients, among which 833 were followed-up by a reoperation during the same stay. A review of medical records identified clearly avoidable and other potentially avoidable reoperations to develop and test the screening algorithm. A logistic prediction model of potentially avoidable reoperations was developed on one randomly chosen half of the data (about 9,000 interventions) and tested on the other half (cross-validation). RESULTS: Two hundred thirty-seven interventions (3%) were followed by a potentially avoidable reoperation, among which 144 were clearly avoidable. The screening algorithm had a sensitivity of 75% and a specificity of 72%. Predictors of potentially avoidable reoperations were surgery categories, diagnosis related conditions, and experiencing prior surgery. The risk score, based on these variables, showed at once a satisfactory discriminative performance (C-statistic=0.76) and goodness-of-fit measure on the validation set. CONCLUSION: The adjusted rate of potentially avoidable reoperations should be included in internal reporting of hospital quality indicators, but further validated in various settings.

Adult↗
PubMed1994

Molting single comb White Leghorns with the use of the Lupron Depot formulation of leuprolide acetate.

Reproductive tract regression and cessation of egg production was induced in 80-wk-old Hy-Line W36 strain hens by an i.m. injection of Lupron Depot at a dose calculated to release 60 micrograms of leuprolide acetate (LA)/kg of BW for 30 d, by restriction of feed intake (FR) for 28 d, or by total feed deprivation (FD) for 7 d followed by feed restriction for 21 d. Egg production in LA and FD groups dropped to 24 and 19% in the first 7 d after initiation of the treatments and to 3.5 and 0% in the 2nd wk. Production of the FR group dropped to 38% during the 1st wk and to 1.7% in the 2nd wk. Production of both nutritionally deprived groups remained near zero through the 5th wk, whereas it increased to 8.2% in the LA group at that time. Hens injected with LA reached 50% production at about 37 vs 45 d for both nutritionally deprived groups. Egg production of control groups remained unchanged during this time. Shell characteristics did not differ significantly among the molted groups throughout most of the 16 wk of the experiment. However shell weight and shell weight per unit surface area of eggs from LA-treated hens were significantly (P < or = .05) lower than those of FR, but not FD, hens at several times. Mean values for shell characteristics of eggs from unmolted hens were significantly lower than those of molted hens. There were no differences in albumen quality between any of the groups at any time.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed2004

Deep-UV Raman spectrometer tunable between 193 and 205 nm for structural characterization of proteins.

A new deep-UV Raman spectrometer utilizing a laser source tunable between 193 and 205 nm has been designed, built, and characterized. Only selected wavelengths from this range have previously been accessible, by Raman shifting of the second, third, and fourth harmonics of the Nd:YAG fundamental in hydrogen. The apparatus was demonstrated to be a useful tool for characterizing hen egg white lysozyme structural rearrangements at various stages of fibril formation. High-quality deep-UV resonance Raman spectra were obtained for both a protein solution and a highly-scattering gelatinous phase formed by fibrillogenic species. In addition to amide bands, strong contribution of nu(12) and ring-C phenylalanine vibrational modes was observed at excitation wavelengths below 200 nm. Remarkably, the Raman cross-section of these modes revealed dramatic change of lysozyme in response to heat denaturation and fibril formation. These results indicate that phenylalanine could serve as a new deep-UV Raman probe of protein structure.

Molecular Probes↗
PubMed2026

A User-Friendly Protocol for Microinjection into Teleost Embryos to Study Gene Function.

Zebrafish (Danio rerio) and medaka (Oryzias latipes) are popular teleost models used in developmental biology and functional genomics. To achieve high-quality and reproducible microinjections, it is essential to have robust protocols for breeding, egg collection, and the precise delivery of genetic material. In this protocol, we present a comprehensive and optimized methodology for setting up breeding tanks under controlled photoperiod conditions to maximize egg yield while minimizing contamination. We provide detailed procedures for sex identification, pair selection, the use of grated breeding inserts, and methods to increase egg collection efficiency. We outline procedures for making injection gel beds, pulling needles, and calibration using one-microliter microcapillaries to achieve consistent nanoliter-scale injections. Our protocol outlines settings for the pico-liter injector that are optimized to deliver a precise amount per pulse with minimal variability. Finally, we demonstrate the application of these methods for gene knockdown using morpholino antisense oligonucleotides, gene knockout using CRISPR-Cas9, and gain-of-function mRNA overexpression experiments. Phenotypic assessments conducted at various developmental stages to evaluate gene-specific effects reveal consistent phenotypic outcomes between the morpholino and CRISPR-Cas9 approaches. This easy and comprehensive protocol enables efficient, precise, and scalable genetic manipulation of zebrafish and medaka embryos, thereby supporting advanced functional studies in developmental biology and disease modeling. To our knowledge, this is the first unified protocol for both zebrafish and medaka microinjection systems achieving 97.7% phenotype penetrance in CRISPR-Cas9 knockouts with precision together with a triple validation approach that confirms gene function across multiple techniques.

Animals↗