Analysis of Gray Fox (Urocyon cinereoargenteus) Fur Harvests in Arkansas

An investigation was conducted on gray fox (Urocyon cinereoargenteus) fur harvest in Arkansas. Data were gathered from a mail survey of Arkansas trappers and from Arkansas Game and Fish Commission fur harvest records from 1939 to 1983. Analyses of these data demonstrated: 1) gray fox were abundant statewide with lower levels in the Delta region; 2) there was a need for fox trappers to keep better records on their trapping efforts, success and composition of catch, including sex and age data; 3) market price: harvest correlation was high (r = 0.956, p \u3c .001); 4) over the past 10 years, the Ozark Mountain region provided the greatest contribution to annual fox harvests, the Ouachita Mountain and Gulf Coastal Plain regions were similar to each other, but lower than the Ozarks, and the Delta region contributed the least, but with a generally stable harvest

Analysis of Arkansas Fur Harvest Records - 1942-1984: II. Species Accounts

Fur harvest records were maintained by the Arkansas Game and Fish Commission on the following 16 furbearers: badger, beaver, bobcat, eastern spotted skunk (civet), coyote, gray fox, long-tailed weasel, mink, muskrat, nutria, opossum, raccoon, red fox, red wolf, river otter, and striped skunk. These harvest records were analyzed for each species in terms of mean pelt price and numbers of pelt sold by region (Ozark Mountains, Ouachita Mountains, Gulf Coastal Plain, and Mississippi Delta) per year. Historical or biological influences important in interpreting species accounts are presented

Analysis of Arkansas Fur Harvest Records - 1942-1984: III. Harvest-Price Relationships

Correlation and linear regression analyses between mean annual pelt price and total harvest of 13 Arkansas furbearer species between 1965 and 1983 were performed for state and regions (Ozark Mountains, Ouachita Mountains, Gulf Coastal Plain, and Mississippi Delta). Statewide, strong correlations (r \u3e 0.80) were identified for bobcat (Felis rufus), coyote (Canis latrans), gray fox (Urocyon cinereoargenteus), mink (Mustela vison), nutria (Myocastor coypus), opossum (Didelphis virginiana), and raccoon (Procyonlotor). Moderate correlations (r = 0.55 - 0.79) were identified for eastern spotted skunk (Spilogale putorius), muskrat (Ondatra zibethicus), river otter (Lutra canadensis), and striped skunk (Mephitis mephitis). Nonsignificant correlations (r \u3c 0.468) were shown for beaver (Castor canadensis) and long-tailed weasel (Mustela frenata). Regional differences were noted for each species

Model to Predict Arkansas Gray Fox Fur Harvests

Linear regression analysis of total gray fox (Urocyon cinereoargenteus) fur harvests from 1954-1983 in Arkansas showed a high correlation with mean pelt values (r = 0.956). Single variable models using linear regression analyses of current season\u27s pelt values (CSPV) and previous season\u27s pelt values (PSPV) were designed to predict fur harvests. These models demonstrated high correlations for predicting harvests (r = 0.933 and r = 0.893 respectively). Regional analyses revealed a high correlation between mean pelt values and harvest for the Ozark Mountain region (r = 0.923), Ouachita Mountain region (r = 0.971 ), and Gulf Coastal Plain (r = 0.975). The Mississippi Delta region correlation of r = 0.756 suggested the interaction of other unidentified variables. It appears that in Arkansas, gray fox fur harvests can be reasonably predicted by using either the CSPV or PSPV models. These models indicate that declines in the total harvest of gray fox in Arkansas since 1980 are probably due to price declines

Effects of Retinoic Acid on Embryonic Chick Skin

The influence of vitamin A on differentiating epithelia was examined in explants of skin from 14-day chick embryos exposed to retinoic acid (RA) in low, moderate, and high doses. The changes observed in RA-treated cultures are both dose- and time-dependent and are reversible when explants are transferred to control medium. The periderm sloughs prematurely and horizontal stratification is lost. Keratinization is inhibited and fewer desmosomes and tonofilaments are seen. Surface epidermal cells develop microvilli, bulge upwards, and detach. Golgi elements, rough endoplasmic reticulum, and polyribosomes are unusually prominent. Mucin granules form and gland-like structures develop with intercellular canaliculi characterized by tight junctions, brush borders, and dense secretory contents. On the basis of present evidence there are several possible mechanisms by which RA could alter epidermal differentiation. RA-induced gaps in the basal lamina allow direct contact between epidermal basal cells and fibroblasts and collagen fibers which could result in inappropriate dermal signals reaching the epidermis. In younger embryos the entire epidermis, including the mitotically inactive surface cells, appears to respond to RA, and this could imply an epigenetic modulation of cell phenotype. Finally, after the formation of a stratum corneum in older embryos only the relatively undifferentiated basal layer shows a metaplastic response, indicating that RA could be acting directly on the genome

Analysis of Arkansas Fur Harvest Records - 1942-1984: I. State and Regional Accounts

Fur harvest records maintained by the Arkansas Game and Fish Commission from 1942-1984 summarized the number of pelts sold by region (Ozark Mountains, Ouachita Mountains, Gulf Coastal Plain, and Mississippi Delta) and the average price per pelt for 16 furbearers. Analysis of these records showed that in the 1979-80 trapping season (the record year for both harvest and value both in Arkansas and the nation), the value of the Arkansas fur harvest ranked 14th nationally (2.12% of total national value). Fur harvests in Arkansas were high in the 1940\u27s, declined in the 1950\u27s and 1960\u27s and then experienced a rapid increase in the 1970\u27s and into the 1980\u27s. In all decades, the Mississippi Delta has ranked first in both numbers of pelts harvested and total value. With the exception of the 1970\u27s, the Delta has been followed by the Ozark Mountains, the Gulf Coastal Plain, and the Ouachita Mountain Region

Arkansas Gray Fox Fur Price-Harvest Model Revisited

Peck and Heidt (1985) proposed a linear model that demonstrated that for gray fox (Urocyon cinereoargenteus) in Arkansas; total fur harvests from 1966-1982 were highly correlated with mean pelt values. Single variable models using linear regression analysis of current season pelt values (CSPV) and previous season pelt values (PSPV) were designed to predict total fur harvests. These models demonstrated high correlations (r =0.93 and 0.89, respectively). In the past 15 years, markets for fur have undergone many perturbations within Arkansas and overseas resulting in great changes in mean pelt prices. In an attempt to evaluate the continued performance of the original model, pelt price and harvest data from 1983-1997 were tested for correlation using linear regression analysis. The results from these tests showed a high correlation. Two specific years (1983 and 1987) were affected strongly by political and economic events. A new model encompassing trapping seasons from 1966 through 1997 was evaluated. Mean pelt value remains a significant predictor of total gray fox fur harvest in Arkansas

An Integrative Approach to Computational Modelling of the Gene Regulatory Network Controlling Clostridium botulinum Type A1 Toxin Production

Clostridium botulinum produces botulinum neurotoxins (BoNTs), highly potent substances responsible for botulism. Currently, mathematical models of C. botulinum growth and toxigenesis are largely aimed at risk assessment and do not include explicit genetic information beyond group level but integrate many component processes, such as signalling, membrane permeability and metabolic activity. In this paper we present a scheme for modelling neurotoxin production in C. botulinum Group I type A1, based on the integration of diverse information coming from experimental results available in the literature. Experiments show that production of BoNTs depends on the growth-phase and is under the control of positive and negative regulatory elements at the intracellular level. Toxins are released as large protein complexes and are associated with non-toxic components. Here, we systematically review and integrate those regulatory elements previously described in the literature for C. botulinum Group I type A1 into a population dynamics model, to build the very first computational model of toxin production at the molecular level. We conduct a validation of our model against several items of published experimental data for different wild type and mutant strains of C. botulinum Group I type A1. The result of this process underscores the potential of mathematical modelling at the cellular level, as a means of creating opportunities in developing new strategies that could be used to prevent botulism; and potentially contribute to improved methods for the production of toxin that is used for therapeutics