The pituitary gland is unique to Chordates, with significant variation within this group, offering an excellent opportunity to increase insight into phylogenetic relationships within this phylum. The structure of the pituitary in adult Teleosts (class: Osteichthyes) is quite different from that in other chordates and is also variable among members of the class. Therefore, a complete description of the structure and development of the pituitary in members of this class is a critical component to our overall understanding of this gland. An obvious teleost model organism is the zebrafish, Danio rerio, as a significant amount of work has been done on the molecular control of pituitary development in this fish. However, very little work has been published on the morphological development of the pituitary in the zebrafish; the present study aims to fill this void. The pituitary develops from cells on the rostrodorsal portion of the head and reaches its final position, ventral to the hypothalamus, as the cephalic flexure occurs and the jaws and mouth form. The pituitary placode is juxtaposed to cells that will form the olfactory vesicles, the stomodeum, and the hatching gland. The volume of the pituitary is greatest at 24 hours post fertilization (hpf). From 24 to 120 hpf, the pituitary decreases in height and width as it undergoes convergent extension, increasing in length with the axis. The adenohypophysis is a morphologically distinct structure by 24 hpf, whereas the neurohypophysis remains indistinct until 72 hpf. The findings of this study correlate well with the available molecular data.
High-affinity LH/hCG binding sites have been identified in both porcine and rabbit uteri. We have now identified these binding sites in rat uteri. We have assessed the binding site specificity and modulation and have searched for binding sites for a related glycoprotein. Radioreceptor assays were performed with membrane homogenates of uterine tissue, and were analysed for binding site specificity, affinity, and capacity. The rabbit and rat LH/hCG binding sites did not bind human TSH or human FSH. Rabbit uterine tissue contained no binding sites for FSH, as determined with 125I-labelled FSH and unlabelled FSH. Pretreatment of rabbits with hCG decreased their uterine binding site capacity from 1.30\m=+-\0.29to 0.46\m=+-\0.01 fmol/mg protein. Pretreatment of castrated rabbits with estrogen or estrogen combined with progesterone did not alter the binding site affinity or capacity. In rats, the uterine binding site number was shown to vary inversely with the serum LH concentration and directly with the ovarian LH/hCG bindig site number during the estrus cycle. Hypophysectomy resulted in a significant increase in uterine binding site capacity in rats. Estrogen treatment prevented this hypophysectomy-induced increase. The function of these LH/hCG binding sites remains uncertain; however, the lack of binding sites for a related glycoprotein and the modulation of these binding sites by hormonal factors strengthen the concept that uterine tissue might respond in a specific manner to direct LH/hCG stimulation. The gonadotropins, luteinizing hormone and fol¬ licle-stimulating hormone, are glycoproteins which act via specific receptors to control gonadal steroid production and gametogenesis in both males and females. Another very closely related glycoprotein, human chorionic gonadotropin also acts through specific receptors. The receptors for LH and hCG are believed to be identical since they cannot be distinguished by competitive receptor assays; thus, hCG is usually employed to measure these recep¬ tors due to its greater stability than LH upon iodi¬ nation (1). Until 1986, when Ziecik et al. demonstrated the presence of specific, high-affinity (Ka=9.90 X 101(1/mol)), low-capacity binding sites for LH/hCG in porcine uterine tissue (2), the gonads were thought to be the only target tissues for these gonadotro¬ pins. The findings of Ziecik et al. prompted us to investigate the presence and possible function of these uterine binding sites. Recently, work in our laboratory has shown LH/hCG binding sites also exist in rabbit uterine tissue with an affinity of 9.20X 1010 (1/mol) and a capacity of 4.65 fmol/mg of protein (3). The work presented in this paper was under¬ taken to determine the existence of these binding sites in yet another animal species, the rat, and to further characterize the binding sites in both rabbit and rat tissue. The demonstration of the specificity of these binding sites in a third species, of the ab¬ sence of binding sites for a related glycoprotein, and of modulation of these binding sites by hor¬ mon...
Twenty-four alleles have been defined for HLA-DPB based on their second exon sequences. This paper describes a novel method, co-digested amplified fragment length polymorphisms (CAFLP), for assigning these alleles to heterozygous patients, as well as to homozygous cell lines. The method depends on co-digestion of amplified DNA by restriction endonucleases and separation of the resultant fragments with polyacrylamide gel electrophoresis. Co-digestion by selected restriction enzymes produces a set of readily discernible fragments that are unique for a given haplotype because the selected restriction sites occur in cis. Consequently, this method provides haplotype information not available from independent digests and allows all known heterozygous genotypes to be identified. Analysis of 103 trios of mother, father, and child, plus 120 normal caucasians, demonstrates the reliability and simplicity of this procedure. This simple typing method results in unambiguous assignment of all current HLA-DPB genotypes in random samples with a high proportion of heterozygous individuals.
DBA/2J mice exhibit audiogenic seizure susceptibility (AGSS) and lower electroshock seizure thresholds compared with C57BL/6J mice. Thyroid function, including thyroxine (T4), 3,5,3'-triiodothyronine (T3), and thyrotropin (TSH) concentrations, T4/T3 ratio, and iodide uptake, of DBA and C57 mice were compared. Thyroid function was also assessed in relation to AGSS and severity in DBA mice. DBA mice have a larger thyroidal pool of iodide due to increased iodide uptake and possibly decreased release, but not to an increased organification rate. This increased iodide uptake exists until about 40 days of age. DBA mice also have a decreased radiochloride space and increased thyroid weight, indicative of enhanced TSH activity. The DBA mice show high T4 and TSH concentrations and a high T4/T3 ratio between the ages of 20 and 40 days. Beginning at 40 days of age the DBA mice have high T4, TSH, and T3 concentrations leading to a T4/T3 ratio approximating the C57 ratio. At any age, DBA mice demonstrating clonic/tonic seizures in response to auditory stimulation have hormone concentrations similar to their 21-day-old counterparts with seizures. Mice that show decreased response to auditory stimulation have hormone concentrations similar to the older age group. The increased thyroid activity of DBA mice is the result of enhanced TSH secretion. The increased TSH production is due to adaptations corresponding to the different age and AGSS. A decreased conversion of T4 to T3 by 3,3,5'-monodeiodinase, is responsible for the increase in TSH due to loss of T3 negative feedback on the anterior pituitary gland. By 40 days of age, the Type I 5'-deiodinase matures whereas the brain deiodinase activity remains subnormal.(ABSTRACT TRUNCATED AT 250 WORDS)
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