Mississippi State University

About: Mississippi State University is a education organization based out in Starkville, Mississippi, United States. It is known for research contribution in the topics: Population & Catfish. The organization has 14115 authors who have published 28594 publications receiving 700030 citations. The organization is also known as: The Mississippi State University of Agriculture and Applied Science & Mississippi State University of Agriculture and Applied Science.

Enhancement of ovulation rate in gilts by increasing dietary energy and administering insulin during follicular growth.

Abstract: Two experiments were conducted to examine influences of dietary energy and insulin on ovulation rate and patterns of luteinizing hormone (LH), follicle stimulating hormone (FSH), glucose, insulin and estradiol in gilts during 6 d before estrus. In Exp. 1, 36 gilts were given altrenogest for 14 d to synchronize estrus. In a factorial arrangement, gilts were fed one of two levels of dietary energy (5,771 or 9,960 kcal metabolizable energy (ME)/d), and given one of two levels of porcine insulin (0 or .1 IU/kg body weight iv every 6 h). Dietary treatments began 4 d before and insulin treatments began 1 d after the last day of altrenogest, respectively, and lasted until 24 h after estrus. Main effect means for number of corpora lutea were 14.0 +/- 1.3 and 17.6 +/- .9 for 5,771 and 9,960 kcal ME (P less than .05), and 14.6 +/- 1.0 and 17.0 +/- .9 for 0 and .1 IU insulin (P less than .05). Number of LH peaks on d 3 was greater for gilts that received 9,960 kcal than 5,771 kcal (3.3 +/- .2 vs 2.7 +/- .2; P less than .05), and for .1 than 0 IU insulin (3.2 +/- .2 vs 2.7 +/- .2; P less than .05). During the first 24 h of sampling, concentrations of LH and FSH were greater (P less than .05) in gilts receiving 9,960 kcal ME plus insulin than for other treatment combinations. Concentrations of estradiol were not affected by treatments. In Exp. 2, two formulations of insulin were evaluated for influence on ovulation rate. All gilts received altrenogest and 9,960 kcal ME/d as in Exp. 1. Then on the first day after altrenogest, seven gilts each received short-acting insulin (as in Exp. 1), long-acting insulin (zinc suspension, 1.0 IU/kg body weight every 18 to 24 h), or served as controls. Ovulation rates were increased (P less than .05) by both insulin preparations (15.6, control; 19.1, short-acting; 18.5, long-acting; SE = 1.2). Concentrations of LH tended to be greater after short-acting insulin, but differences were not significant (P = .13). We conclude that increases in ovulation rate produced by dietary energy and insulin are not necessarily accompanied by changes in gonadotropins or estradiol.

Simple Sequence Repeat–Based Assessment of Genetic Diversity in Cotton Race Stock Accessions

Abstract: Effective use of converted day-neutral Gossypium hirsutum L. race stocks in cotton genetic improvement programs depends on the extent of genetic variation for desirable alleles and the accurate characterization of the variability within and among germplasm accessions in the collection. This study was conducted to survey the molecular variation in the converted race stock collection by using simple sequence repeat (SSR) DNA markers and to determine the genetic distance of each race stock from a typical G. hirsutum cultigen. The molecular marker data will also provide a measure of the degree to which the recurrent photoperiodic parent has been recovered during backcross conversion to day-neutral stocks. Fifty-six flourescently labeled SSR primer pairs arranged in multiplex bins were used to genotype 97 day-neutral BC 4 F 4 race stock accessions. The majority of the accessions had genetic distances 0.25. In some families, the primitive photoperiodic parent was recovered, and in others there was extensive linkage drag from the day-neutral donor parent. The recovery of the primitive recurrent parent could be improved by marker-assisted backcrossing with SSR markers reported in this experiment. Careful genotyping with SSR markers prior to introgression into breeding programs is suggested to ensure maximum genetic diversity and integrity of the exotic race-stock donor germplasm.

Pollen-Based Screening of Soybean Genotypes for High Temperatures

Abstract: Soybean [Glycine max (L.) Merr.] reproduction is sensitive to temperatures . 35C. Two studies were conducted to determine temperature effects on soybean pollen germination (PG) and to detect genotypic differences. Pollen collected from 44 genotypes (Maturity Groups III to VI) grown outdoors was subjected to in vitro temperatures from 15 to 50 Ca t 5C intervals. Genotypes differed significantly for in vitro PG percentage (mean of 81%) and tube length (mean of 437 mm). Mean cardinal temperatures (Tmin ,T opt, and Tmax) were 13.2, 30.2, and 47.2C for PG and 12.1, 36.1, and 47.0C for pollen tube growth. Genotypes differed for leaf cell membrane thermostability (CMTS), but CMTS did not correlate with pollen parameters. Cumulative temperature response index, CTRI (unitless), of each genotype calculated as the sum of eight individual stress responses (ISRs) derived from maximum PG, maximum pollen tube length (PTL), and the maximum (Tmax), minimum (Tmin), and optimum (Topt) temperatures for PG and for PTLs was used to group genotypes for temperature tolerance. Heat-tolerant genotype (DG 5630RR) was less sensitive to high temperature (38/30C) compared with heat-intermediate (PI 471938) and heat-sensitive (Stalwart III) genotypes that had deformed pollen, with reduced apertures and collumellae heads. Hence, pollen can be used as a screening tool for heat tolerance. Most sensitive to temperature was D88-5320 with a CTRI of 6.8, while AG 4403RR was most tolerant with a CTRI of 7.5. Elevated [CO2] did not modify reproductive parameters or CTRI. The study also revealed that heat tolerance of vegetative tissue had little or no relationship with the heat tolerance of reproductive tissue. Maturity groups lacked a specific trend for tolerance to high temperature. The identified high temperature-tolerant genotypes and temperature-dependent pollen response functions might be useful in soybean breeding and modeling programs, respectively.

Nonfamily Members in Family Firms: A Review and Future Research Agenda:

Abstract: The study of the roles, impact, and challenges associated with nonfamily members in family firms has generated considerable attention in the literature. To gain an appreciation of this body of knowledge, we systematically review 82 articles on nonfamily members in family firms that were published in 34 journals over the past three decades. We synthesize the literature according to three broad, yet overlapping themes: preemployment considerations, employment considerations, and outcomes of nonfamily employment. We then offer a future research agenda that integrates these themes to guide the advancement of knowledge on nonfamily members in family firms.