The casein kinases Yck1p and Yck2p act in the secretory pathway, in part, by regulating the Rab exchange factor Sec2p.

Sec2p is a guanine nucleotide exchange factor that activates Sec4p, the final Rab GTPase of the yeast secretory pathway. Sec2p is recruited to secretory vesicles by the upstream Rab Ypt32p acting in concert with phosphatidylinositol-4-phosphate (PI(4)P). Sec2p also binds to the Sec4p effector Sec15p, yet Ypt32p and Sec15p compete against each other for binding to Sec2p. We report here that the redundant casein kinases Yck1p and Yck2p phosphorylate sites within the Ypt32p/Sec15p binding region and in doing so promote binding to Sec15p and inhibit binding to Ypt32p. We show that Yck2p binds to the autoinhibitory domain of Sec2p, adjacent to the PI(4)P binding site, and that addition of PI(4)P inhibits Sec2p phosphorylation by Yck2p. Loss of Yck1p and Yck2p function leads to accumulation of an intracellular pool of the secreted glucanase Bgl2p, as well as to accumulation of Golgi-related structures in the cytoplasm. We propose that Sec2p is phosphorylated after it has been recruited to secretory vesicles and the level of PI(4)P has been reduced. This promotes Sec2p function by stimulating its interaction with Sec15p. Finally, Sec2p is dephosphorylated very late in the exocytic reaction to facilitate recycling

The Effects of Long Term Selection for Reduced Backfat and Increased Loin Muscle Area on Meat and Eating Quality Traits in Duroc Swine

A study was conducted to evaluate differences in performance, carcass composition, and eating quality characteristics of pigs sired by purebred Duroc boars currently available and pigs sired by purebred Duroc boars from the mid 1980’s. Two lines were developed by splitting and randomly allocating littermate and ½ sib pairs of females to matings by current (CTP) or old (OTP) time period boars. Subsequent boar, barrow, and gilt progeny from two replications were weighed on test at a group mean live weight of 140 lbs. Off-test ultrasonic LMA, BF10, and IMF measurements were collected on 789 pigs at a mean live weight of 240 lb. Records on pigs sired by CTP boars, from both replications (n=556), represented 23 sires while pigs sired by OTP boars (n=231) consisted of 15 sire groups. All available barrows and randomly selected gilts (n=277) were sent to a commercial abattoir and measurements of tenth-rib backfat (CBF10), last rib backfat (CLRBF), last lumbar backfat (CLLBF), and loin muscle area (CLMA) were collected. Chemical intramuscular fat percentage was determined by lab analysis of a loin sample from the 10th rib face of the longissimus muscle. Additional meat and eating quality traits measured were: Minolta reflectance and Hunter L (24 and 48 h); pH (24 h and 7 d); water holding capacity; subjective visual scores for color, marbling, and firmness (48 h); Instron tenderness, cooking loss, and trained sensory panel evaluations (7 d). Six serial ultrasonic measurements of 10th rib loin muscle area (LMA), off-midline backfat (BF10), and intramuscular fat percentage (IMF) from the first replication were collected every two weeks and used to assess deposition rate and growth pattern differences. There was no significant difference in average daily gain of pigs sired by boars from the two time periods. Pigs sired by CTP boars had larger (P \u3c 0.05) LMA measurements and less BF10, while pigs sired by OTP had significantly more IMF. Carcass evaluation revealed larger CLMA measurements, and significantly less CBF10, CLRBF, and CLLBF measurements for pigs sired by CTP boars. Pigs sired by OTP boars had a higher intramuscular fat percentage, lower Instron tenderness values, and higher subjective marbling and color scores than pigs sired by CTP boars (P \u3c 0.05). There were no significant differences between time periods for Minolta reflectance, Hunter L (24 and 48 h), water holding capacity, pH (24 h and 7 d), and subjective firmness scores. Trained sensory evaluations revealed higher (P \u3c 0.05) flavor scores and lower off-flavor scores for OTP sired pigs; however, no significant differences in tenderness score, juiciness score, chewiness score, and cooking loss were found between lines. Progeny of OTP boars began the test period at heavier weights and begin to decrease in daily body weight gain toward the conclusion of the test period, finishing with no advantage in body weight when compared to progeny of CTP boars. The analysis of serial backfat measurements revealed a linear pattern of backfat deposition between 150 and 270 lbs. Pigs sired by OTP boars deposited more backfat (

Genetic Aspects of Female Longevity

Longevity of the breeding female has both economic and animal welfare implications for the swine industry. High culling levels lead to increased replacement rates and reduce lifetime productivity for individual breeding females and the breeding herd. Greater replacement rates increase production costs related to purchase (or development), isolation, and acclimation of replacement females. PigCHAMP [1-5] summaries (Table 1) from 1998 through 2003, report annualized replacement rates of \u3e 50% and average herd parity of only 2.5 litters. Breeding herd productivity and economic sustainability are compromised when females are culled early in life and prior to achieving a positive return on investment. Breeding program design and genetic selection decisions clearly influence sow longevity and establish the base for a profitable, sustainable breeding herd

Effect of Technician, Machine, and Animal Body Composition on Accuracy of Ultrasonic Measures of Backfat and Loin Muscle Area in Swine

Records (n = 11,305) from the 1998 to 2003 National Swine Improvement Federation (NSIF) ultrasound certification programs were used to determine the effect of technician, machine (A-mode and B-mode: Aloka 500, Classic Scanner 200), and level of animal fat depth and loin muscle area on the accuracy of tenth rib off-midline backfat (BF10) and loin muscle area (LMA) measured on live pigs

Growth Comparison and Fecal Mineral Excretion of Inorganic and Organic Trace Mineral Supplementation in Swine

Fecal Analysis, off-test weights, and ultrasonic measurements were used to determine the response of BioplexTM trace minerals on the fecal mineral excretion (copper Cu, iron Fe, and zinc Zn) and growth and performance traits measured on live pigs (n=528). The use of BioplexTM mineral supplementation on phase fed growfinish pigs could potentially decrease the amount of heavy metal and nutrient excretion without impacting the overall performance of the animal. These organic mineral supplements can ultimately be fed to finishing swine without having a significant effect on percent lean (live or carcass), loin muscle area (LMA), backfat (BF10), average daily gain (ADG), or feed efficiency (FE). The use of BioplexTM trace minerals has the potential to reduce the environmental impact of swine production without any loss of production efficiency to the producer. Future work in the use of BioplexTM trace minerals and other mechanisms to reduce the environmental impact of swine production is warranted

Selection for Intramuscular Fat in Duroc Swine – An Update

Long-term progress or improvement in many economically important traits is ultimately the responsibility of the seedstock supplier. If selection progress is to be made in traits of economic importance, the trait must: 1) be accurately measurable, 2) show sufficient heritability, and 3) display an adequate level of variation. For such reasons, tremendous progress has been made in the swine industry toward increasing lean meat percentage over the past quarter century. However, in more recent years, meat quality traits have received more attention and have become more important in breeding programs as producers and processors try to meet consumer demands for high quality, nutritious products