Factors influencing rate of decline in a Merriam's wild turkey population

We investigated population growth rate (λ) for a Merriam's wild turkey (Meleagris gallopavo merriami) population in the northern Black Hills, South Dakota, USA. We constructed and evaluated a females-only matrix population model. Our estimate of asymptotic λ, derived from estimates of vital rates obtained from 2016–2018 was 0.74 (95% CI = 0.60, 0.88), which indicates that the vital rates were inadequate to sustain the population. Elasticity values were highest for changes in adult survival probability followed by, in order, changes in juvenile survival, yearling survival, and adult reproduction. We could only achieve stable or growing populations (i.e., λ ≥ 1) by increasing the probability of adult and yearling survival (holding all other vital rates constant). Estimated adult survival rate in the work reported here was lower than values reported for other populations in the Black Hills; therefore, managing for increased female survival (≥0.68) may be the most practical strategy for promoting wild turkey population growth in this system. We recommend no female harvest during any open turkey season.     

Factors influencing genetic counseling attendance rate: a geographically based study

A study of factors influencing genetic counseling attendance rate has been conducted in the Bouches-du-Rh?ne area, in the south of France. In this area, a birth defects monitoring system (Eurocat n. 22) annually covers 23,000 births. All the genetic services are delivered by only one genetic center located in Marseilles, and the data collected are computerized. The comparison of these two data bases gives an opportunity to estimate the rate of genetic counseling attendance after the occurrence of an affected stillbirth or live birth. Among the parents of 358 infants born in 1983-84 in this area with a pathology requiring genetic counseling, 226 (63 per cent) attended the Genetic Center within the first year after birth. The rate of attendance is statistically higher (p less than 0.01) for the parents who had a stillbirth (78 per cent) than for those who had a live birth (57 per cent). It is also higher (p less than 0.01) for the Marseilles maternities group (68 per cent) than for the group outside Marseilles (50 per cent). The referral delays are also analyzed according to malformation etiology and to viability of the child by the eighth day of life. Besides evaluating a particular genetic center's effectiveness in diffusing information to the public concerned, this work shows that couples' request is strongly dependent on a psychological need.     

Factors influencing the cholesterol esterification rate in lecithin cholesterol acyltransferase radioassay

Factors affecting the esterification rate of cholesterol by lecithin cholesterol acyltransferase (LCAT E.C. 2.3.1.43) in native cold labelled substrates (human, rabbit, rat serum, plasma, VLDL, LDL depleted serum, rabbit intraocular fluids) repaired by use of ready-made 14C-cholesterol discs (Cholesterol kinetics LCAT-test, UVVVR, Czechoslovakia) were investigated. EDTA added to the serum during the cold incubation (18 h, 0 degrees C-4 degrees C) increased the rate of esterification due to elimination of Ca2+ ions. The similar stimulating effect was found in the presence of mercaptoethanol (ME) in the serum, while in the plasma already stimulated by EDTA no additional effect by ME could be noticed. Freezing and thawing did not affect the fractional esterification rate (FER-per cent of total serum unesterified cholesterol esterified per hour) in normolipidaemic sera, whereas in hyperlipidaemic sera, particularly those with high levels of VLDL, FER was stimulated. Esterification partially proceeded during the cold incubation of serum or plasma with 14C-cholesterol ready-to-use discs, attaining the values of about 0.3%/h and 2-6%/h, respectively, in human sera and in rabbit and rat sera. The starting level of esterification did not affect the linearity of LCAT reaction during warm incubation (30 min at 37 degrees C), neither was the absolute value of FER changed as compared with cold labelled sera with those inhibited by DTNB and reactivated by ME. Substantial LCAT activity was also detected in extremely diluted substrates--such as intraocular fluid collected from rabbits with induced uveitis or after preceding paracentesis.(ABSTRACT TRUNCATED AT 250 WORDS)     

Factors influencing the rate of electron transport in different respiratory pathways of bacteria

The rate of electron transfer by a respiratory pathway as dependent on pH, temperature, concentration of cyanide and concentration of azide was followed in washed non-growing cells ofCitrobacter. Three respiratory pathways leading to three terminal electron acceptors, i.e. oxygen, tetrathionate and nitrate, were investigated. It was found that these pathways mutually differ in their response to pH, temperature, cyanide and azide and conditions favouring inhibition or stimulation of one electron transport pathway relatively to the other two pathways were established.     

Factors influencing genetic counseling attendance rate: A geographically based study

Abstract

A study of factors influencing genetic counseling attendance rate has been conducted in the Bouches‐du‐Rhône area, in the south of France. In this area, a birth defects monitoring system (Eurocat n°22) annually covers 23,000 births. All the genetic services are delivered by only one genetic center located in Marseilles, and the data collected are computerized. The comparison of these two data bases gives an opportunity to estimate the rate of genetic counseling attendance after the occurrence of an affected stillbirth or live birth. Among the parents of 358 infants born in 1983–84 in this area with a pathology requiring genetic counseling, 226 (63 per cent) attended the Genetic Center within the first year after birth. The rate of attendance is statistically higher (p < 0.01) for the parents who had a stillbirth (78 per cent) than for those who had a live birth (57 per cent). It is also higher (p < 0.01) for the Marseilles maternities group (68 per cent) than for the group outside Marseilles (50 per cent). The referral delays are also analyzed according to malformation etiology and to viability of the child by the eighth day of lue. Besides evaluating a particular genetic center's effectiveness in diffusing information to the public concerned, this work shows that couples’ request is strongly dependent on a psychological need.     

Primary biodegradation of a series of alkyl sulfosuccinates by mixed bacterial culture

A mixed bacterial culture capable of primary biodegradation of sodium alkyl sulfosuccinates R¹-OOC−CH(SO₃Na)−CH₂−COO−R² was obtained from soil microorganisms by enrichment cultivation and adaptation in the presence of mono-n-dodecyl sulfosuccinate. Gram-negative psychrophilic bacteria with proteolytic, lipolytic and ammonifying activities were prevalent in the culture. The process of primary biodegradation of alkyl sulfosuccinates can be described by firstorder reaction kinetics. The rate constants for linear esters were ascending in the order C₄<C₅<C₆ (45 μmol/min per g cell protein) and further descending with increasing length of the carbon chain C₆>C₈>=C₁₃. Substitution of cyclohexyl for n-hexyl group resulted in fourfold decrease in biodegradation rate. Terminal branching of alkyl chain does not affect the rate of primary biodegradation.     

Factors influencing the fertility of a cattle population.

The many factors which may influence the fertility of a cattle population are reviewed. The following subjects are discussed: the bull, the method of insemination, the cow, the conditions of herd management and chance. Particular attention is paid to factors related to the conditions of herd management. These are the climate, the season, the size of the herd, the housing system, the choice of a bull, hygiene at the time of calving, the interval between parturition and the first insemination, detection of oestrus, the time of insemination during oestrus, nutrition, selection and the culling of cows. In the discussion, the effect which the various factors may have on fertility is illustrated by a case in point.     

Factors influencing the rate of preantral and antral growth of mouse ovarian follicles in vitro.

The development of a culture system for individual mouse ovarian follicles using a low concentration of homologous serum, human follicle-stimulating hormone (hFSH) and a simple combination of growth factors is reported. Preantral follicles, 150 microns in diameter, with thecal cells attached were isolated mechanically. After 6-7 days on a Millicell membrane, a high proportion of the preantral follicles cultured individually with hFSH grew to morphologically normal large antral follicles (400-500 microns in diameter) with high oestradiol secretion. Without hFSH, the follicles grew to approximately 275 microns diameter in 6 days, but did not form antra or secrete oestradiol. The growth trajectory (overall pattern of growth formed by daily measurements of diameter) of each follicle was recorded and used as a measurement of response to experimental variation of culture conditions. The rapidly growing follicles were morphologically normal, but those that grew more slowly showed some abnormality or atresia and secreted less oestradiol. Follicles cultured in groups without being in direct contact with each other showed much poorer growth than those grown individually, but the inhibition was not uniform and some follicles grew larger than others in the group. Follicles that contacted each other directly in culture tended to fuse into one mass and their growth was substantially inhibited. Even under these conditions, one follicle often continued to grow slowly while the others degenerated. Such alteration of growth patterns suggests interfollicular paracrine control and may be a means of three-dimensional spacing of follicle growth within the ovary, as well as part of the mechanism of follicle selection. The dose-response curve based on the mean growth trajectory of follicles cultured individually, produced increasing rates of growth with 12.5-100 miu hFSH ml-1. Higher concentrations of hFSH did not increase growth rate further, but oestradiol secretion continued to increase with increasing hFSH up to the maximum used (2000 miu ml-1).     

Factors influencing the assimilation of arsenic in a deposit-feeding polychaete

We investigated mechanisms leading to the assimilation of particle-bound arsenic (As) ingested by the deposit-feeding polychaete Alitta succinea using a radiotracer approach. The release of As from different particle types into extracted gut fluid or bovine serum albumin (BSA), a gut fluid mimic, was measured. In addition, gut fluid proteins were analyzed by separating proteins via 2D gel electrophoresis, and protein peptide sequences were determined by mass spectrometry. Major ions in the gut fluid were measured by ion chromatography and metals by mass spectrometry. Percentages of particulate As release were related to As assimilation efficiencies (AEs) in polychaetes feeding on different particle types. AEs of As were highest from radiolabeled pure diatoms (72%) and radiolabeled diatoms added to sediment (51%), lower from radiolabeled sediment (10%), and lowest from a radiolabeled iron oxide mineral, goethite (2%). It appears that As release from particles is a necessary but not sufficient requirement of As assimilation. For example, 15% of As was released from goethite into the gut fluid but only 2% was assimilated by A. succinea. Our results suggest that the likelihood of As assimilation is higher when it is bound to an organic compound of nutritional value in the ingested particles.     

Factors influencing the angular velocity of a human limb segment

The angular velocity of a knee extension performed after flexion with different range and velocity, i.e. the kicking movement with stabilized thigh, was investigated and described. In addition, the maximum velocity of extension reached after prestretch was compared to that obtained in trials without prestretch. The maximum velocity of extension varied from 213 to 1087 degrees s-1 depending on the range and velocity of prestretch. In trials without prestretch the velocity of extension was worse up to 43% when small range of movement was involved. In trials with full range of movement the velocity of extension was similar in the tasks with and without prestretch. In this context the possible role of elastic energy is discussed. The method used was electrogoniometry.     

Factors influencing the onset of egglaying in a cecidomyiid fly

Abstract The timing of the onset of egglaying in the Hessian fly, Mayetiola destructor (Say), is influenced by several exogenous and endogenous factors. Mated females initiated egglaying 48 h earlier than virgins and laid 3–4 times more eggs before dying. The effects of mating on the onset of egglaying were further modified by several other factors whose effects were measured in hours rather than days. Increases in ambient temperatures experienced by mated females shortened the post-mating pre-ovipositional transition phase; however, the effects of temperature were not linear throughout the temperature range. Age of females at the time of mating also influenced the onset of egglaying. Females that mated 1 , 2 and 3 h after eclosion spent 190 , 160 and 120 min in the post-mating transition phase, respectively. Effects of age were also observed when females were mated over the three calling periods that comprise the 3-day lifespan of the adult female. Linear regressions of transition times on time of mating had similar slopes for first and second day post-eclosion females but were offset such that first-day females mated late in the morning had similar transition times to second-day females mated early in the morning. By the third day post-eclosion, transition times showed no significant changes when females were mated throughout the calling period. Possible mechanisms underlying the effects of mating, temperature, and female age on post-mating pre-oviposition transition times are discussed.     

Factors influencing the optimum sex ratio in a structured population

W. D. Hamilton (1967, Science 156, 477-488) calculated the optimum sex-ratio strategy for a population subdivided into local mating groups. He made three important assumptions: that the females founding each group responded precisely to the number of them initiating the group; that ail broods within a group matured synchronously; and that males were incapable of dispersing between groups. We have examined the effects of relaxing each of these assumptions and obtained the following results: (1) When broods mature asynchronously the optimum sex ratio is considerably more female biased than the Hamiltonian prediction. (2) Increasing male dispersal always decreases the optimum female bias to the sex ratio, but it is of particular interest that when moderate levels of dispersal are coupled with asynchrony of brood maturation then the optimum strategy is relatively insensitive to changes in foundress number. (3) When females cannot precisely determine the number of other foundresses initiating the group then the optimum strategy is almost exactly the strategy appropriate to a group of average size. These effects can be most easily understood in terms of local parental control (LPC) of the sex ratio. Through LPC a founding female can alter the mating success of her sons by altering the sex ratio of her brood. Asynchrony in the maturation of broods within a group increases the control that a founding female has over the mating success of her sons, whereas male dispersal reduces it. We have shown that the role of LPC and the role of inbreeding, which favors a female-biased sex ratio in haploidiploid species, are independent and that their effects can be combined into a single general formula r = (1-(r2/z2) E(alpha z/alpha r]/(1 + I). The concept of LPC can also be used to interpret two factors which have been proposed to select for the Hamiltonian sex ratios: local mate competition is LPC acting through sons; and sib mating is LPC acting through daughters.