Translational regulation of the differential synthesis of nonmuscle tropomyosin isoforms

Regulation of the differential synthesis of tropomyosin (TM) isoforms in chicken embryo fibroblasts was studied. Cell-free translation experiments with total RNA and Northern blot analyses of TM mRNAs from fractionated polysomes were performed. Unlike the major isoforms, mRNAs encoding at least one of the minor isoforms were only partially associated with the heavy polysomes. Thus, these experiments revealed that translational regulation plays a role in controlling the relative amounts of major and minor isoforms in the cell.     

Even if the fetus is not a person,abortion is immoral: The impairment argument

Much of the debate about the ethics of abortion has centered on whether the fetus is a person. In an attempt to sidestep this complex issue, I argue that, even if the fetus is not a person, abortion is immoral. To arrive at this conclusion, I argue that giving a fetus fetal alcohol syndrome is immoral, and that if this is so, then killing the fetus is immoral. Roughly, this is because killing the fetus impairs it more than giving it fetal alcohol syndrome. Since abortion (in most cases) amounts to killing the fetus, this means that abortion (in most cases) is immoral. I defend the premises of this argument against a plethora of objections, concluding that they either do not work, or commit their proponent to a controversial position.     

Vaginally administered PGF2alpha for cervical dilatation in nulliparas prior to suction curettage

Because of the need for an atraumatic method to dilate the cervix when performing artificial abortion by suction curettage, cervical dilatation following vaginally administered PGF2alpha was studied. A 50 mg PGF2alpha vaginal suppository was administered to 40 (treated group) first trimester nulliparas 3 hours prior to progressive cervical dilatation from a 19 (circumference in mm) Pratt dilator to a 35 Pratt dialator. The smallest-sized dilator that met resistance was interpreted as being the amount of clinically significant cervical dilatation. The results were compared to 20 (control group) first trimester nulliparas who received no PGF2alpha studied in an identical manner. Independent of gestational age, treated patients were dilated significantly more than the control patients. When subjects of similar gestational age were compared, PGF2alpha treated subjects were more often dilated sufficiently to perform abortion (55%) by suction curettage than control group subjects (5%). Those PGF2alpha subjects needing further dilatation to accept an appropriate sized cannula for their gestational age needed less dilatation than did those subjects of similar gestational age in the control group. No serious complications of PGF2alpha per se were observed and the most frequent side effects, vomiting and diarrhea, did not appear severe enough to limit the clinical practicability of the method.     

Using Marine Snails to Teach Biogeography and Macroevolution: The Role of Larvae and Dispersal Ability in the Evolution and Persistence of Species

While some marine animals are capable of traveling great distances, many have limited mobility as adults and spend the majority of their lifetimes in a small geographical area or may even be cemented to a single place. While it might be expected that species with limited mobility would have small geographic distributions, some nevertheless occur over very large areas. This is the case for some marine snails (gastropods). A key factor that impacts the geographic distribution of marine snails is the type of larvae they have during the phase of their life history that follows hatching from an egg. Because adult snails do not typically travel vast distances, the mobility of the larval stage determines the species?? ability to reach new territories. Some larvae are capable of long-distance travel, while others are not. An important component of the process of speciation involves geographic isolation, so the type of larvae a snail species possesses impacts the likelihood that it will become geographically isolated and give rise to a new species. Larval form also affects how long snail species will persist on geological timescales before going extinct, as well as rates of speciation. This paper briefly reviews the evolutionary consequences of different types of larval development in marine gastropods (especially cone snails, which are one of the most diverse groups of marine animals), particularly in determining the dispersal ability and geographic ranges of individual species, the amount of genetic exchange among populations within species, and the duration of species through time. The goal of this short review is to provide context and examples for classroom discussions of the connections between biogeography and macroevolution. Furthermore, a classroom activity is presented that involves students?? using information about snail life history and biogeography to develop research plans (and predicted results) that could be utilized to test (i.e., support or reject) several macroevolutionary hypotheses.     

Robbery-Related Injury in Convenience Stores: Estimating Lifetime Risk and Identifying High-Risk Populations

Robbery-related injuries constitute a major risk for convenience store workers in the United States. Studies that focus on the injury outcomes associated with convenience store robbery are extremely limited in number. This is a prospective study of 1271 convenience stores in three metropolitan areas of Virginia between February 1, 1995 and September 30, 1996. The study quantifies the lifetime risk for an occupational robbery-related injury occurrence and determines the relative importance of various types of factors in the classification of high risk stores. Lifetime risk was estimated by calculating the probability in convenience stores for having one or more employee(s) sustain at least one robbery-related injury over a range of years that a store could be in operation. Results indicate that knowledge of the circumstances of the robbery are needed to maximize the identification of high risk stores. Estimated lifetime risk reaches 567 stores with an occupational robbery-related injury occurrence per 1,000 stores in operation after 45 years. This study addresses limitations of previous research by including information on clerk resistance and the number of robbers in its analysis. These two circumstantial characteristics of robbery have been previously hypothesized to be associated with robbery-related injury.     

Organizational–Activational Concept Revisited: Sexual Differentiation in an Atherinomorph Teleost

Because of its numerous sexually dimorphic characters, the Western mosquitofishGambusia affinis affinisis an excellent vertebrate system for addressing questions concerning sexual differentiation. In this review, the actions and limits of gonadal sex steroids, specifically testosterone, on the development of the sexually dimorphic anal fin and its axial and appendicular support are described. Data from our laboratory show that the critical period in this species for the anterior transposition of the male anal fin and its appendicular support occurs during the late embryonic period and that this differentiation of the male phenotypic genital areaduring the critical period is regulated by androgen.