Zinc fingers and other domains cooperate in binding of Drosophila sry beta and delta proteins at specific chromosomal sites.

The closely related Drosophila serendipity (sry) beta and delta zinc finger proteins display consensus in vitro DNA recognition sequences differing by 4 of 13 nucleotide positions and bind in vivo to distinct sets of sites on polytene chromosomes. We compared the pattern of in vivo chromosomal binding of deleted forms of the sry delta protein fused to beta-galactosidase and expressed in Drosophila transgenic lines. Results show that the carboxy-terminal DNA-binding finger domain is required and sufficient for binding at specific chromosomal sites but that this binding does not nearly reproduce the wild-type pattern. An NH2-terminal domain of the sry delta protein is essential to its specificity of in vivo interaction with chromatin. In vitro and in vivo experiments using reciprocal finger swap between the sry beta and delta proteins suggest that the in vivo specificity is dependent on selective protein-protein contacts at defined chromosomal sites, in addition to DNA specific recognition.     

Absence of Turner stigmata in a 46,XYp-female

A 46,XY female patient with streak gonads and a large deletion of Yp is described. The deletion included the Y chromosomal genes SRY, ZFY, and RPS4Y. The patient did not display any Turner stigmata, such as webbing of the neck, cardiac or other abnormalities. The findings argue against an important role of RPS4Y in the prevention of Turner stigmata in males and are consistent with a role of SRY in testis differentiation in humans.     

Prolactin modulates steroidogenesis by rat granulosa cells: I. Effects on progesterone

Either testosterone or follicle-stimulating hormone (FSH) stimulates progesterone secretion by granulosa cells from rats but the combination of the two hormones increases progesterone production in a synergistic manner. We have investigated the effects of graded doses of prolactin (0, 0.02, 0.2, 2, or 10 micrograms/ml) alone or in combination with testosterone (0.5 microM), FSH (300 ng/ml), or FSH + testosterone on progesterone secretion by granulosa cells at two stages of differentiation. Relatively undifferentiated granulosa cells from immature, diethylstilbestrol-treated, hypophysectomized (HPX) rats were cultured in defined (serum-free) medium for 3 days. More highly differentiated granulosa cells were obtained on the morning of proestrus from the preovulatory follicles of 30-day-old rats induced to undergo an estrous cycle by injection with 4 IU pregnant mare's serum gonadotropin; these cells were cultured in medium containing 10% fetal bovine serum. Prolactin alone did not enhance the negligible secretion of progesterone by cells from HPX rats, but increased progesterone secretion by cells from proestrous rats. Prolactin significantly enhanced the stimulatory effects of testosterone or FSH alone on cells from both HPX and proestrous rats. When cultures containing both FSH + testosterone were treated with prolactin, progesterone secretion by cells from proestrous rats was significantly enhanced, whereas secretion by cells from HPX rats was significantly depressed. Therefore when cells from HPX rats were cultured with both FSH and testosterone, the direction of the effect of prolactin was reversed from that observed with prolactin + FSH or testosterone alone, and from that observed when cells from proestrous rats were cultured with prolactin + FSH + testosterone.(ABSTRACT TRUNCATED AT 250 WORDS)     

Genetic structure of natural populations of the red-spotted newt,Notophthalmus viridescens

Genetic variation is described at 15 loci in 2 neotenic and 12 nonneotenic populations of red-spotted newts. Though high levels of genetic similarity (I=0.990) were found among all populations, allele frequencies at six of the eight most polymorphic loci show significant heterogeneity across populations. Change in allele frequencies at two of these loci (Pep-2 and Ldh-1) is significantly correlated with latitude. Interspecific homologies are established for newt peptidases based on substrate specificities and lactate dehydrogenases based on tissue distribution, thermal stability, and kinetic properties. Nonneotenic populations are highly variable (H=0.157) and neotenic populations are only slightly, but significantly, less variable (H=0.120). The high levels of heterozygosity detected in nonneotenic populations may result from large effective population size and/or environmental heterogeneity. The unexpectedly high heterozygosity values obtained for the neotenic populations may indicate adult dispersal or the presence of some previously undetected red efts at these localities. In any case, a major change in life history has apparently had little effect on the genetic structure of these populations.This research was supported by grants from the Blakeslee Fund of Smith College.     

Passive Transfer of Lambert-Eaton Myasthenic Syndrome in Mice: Decreased Rates of Resting and Evoked Release of Acetylcholine from Skeletal Muscle

Mice were injected for 1-2 months daily with 10 mg immunoglobulin G (IgG) from four patients with Lambert-Eaton myasthenic syndrome (LEMS); control mice were injected with pooled human IgG from normal donors. Gastrocnemius muscles were homogenised for the assay of acetylcholine (ACh), choline acetyltransferase (ChAT), and cholinesterase (ChE). The ACh, ChAT, and ChE contents of gastrocnemius muscles from "LEMS mice" were about the same as the control values, which were 180 pmol, 40 nmol X h-1 (37 degrees C), and 15 mumol X h-1 (37 degrees C), respectively. Hemidiaphragms were treated with an irreversible ChE inhibitor (Soman) and incubated at 20 degrees C for estimation of ACh release. Resting ACh release from experimental muscles was reduced by about 25% (P2 less than 0.05) and the release evoked by 3 s-1 nervous stimulation by 50% (P2 less than 0.05). On the other hand, 50 mM KCl-induced transmitter release was not abnormal in LEMS mice. The findings indicate that IgG antibody from patients with LEMS may bind to nerve terminal determinants that are involved in quantal and nonquantal ACh release.     

Levator advancement technique for eyelid ptosis

There have been many procedures advocated for the treatment of eyelid ptosis. The technique advocated in this paper consists of careful dissection and identification of anatomic landmarks, including preaponeurotic fat, Whitnall's superior transverse ligament, and the vertically oriented blood supply of the levator muscle. The attachment of the levator muscle into the cephalad portion of the levator muscle into the cephalad portion of the levator aponeurosis can be identified and easily dissected in order to perform the procedure of detachment and advancement to the tarsal plate. This procedure for ptosis has been successful in management in moderate to severe ptosis and in some cases has actually increased the muscle function, thereby enhancing the result. In this technique, the full length of levator muscle remains, so maximum excursion is achieved postoperatively. In addition, this surgical approach may be utilized for levator-lengthening procedures in cases of thyroid exophthalmus or overcorrected ptosis simply by performing the reverse procedure of detachment and insertion of a spacer based on the same ratio. Good results have been achieved in over 20 patients, with the exception of two patients who had absent to poor function and in whom undercorrection was present postoperatively.     

STUDIES ON LYMPHOCYTES

Some of the time parameters of the cell cycle in bovine thoracic duct lymphocytes have been estimated by analysing labeled mitoses curves, and by double labeling. The two methods gave similar estimates of T_s. Thus, T_s measured directly from labeled mitoses curves varied from 4 to 6 hr, while the estimates from double labeling were 4.8 and 4.5 hr. T _G measured directly from labeled mitoses curves was 5 hr, and estimates of T_G from the values of T_s ranged from 6.3 to 7.7 hr. The present data confirm the short generative cycle of large thoracic duct lymphocytes. Extracorporeal irradiation of the lymph (ECIL) had no detectable effect on the cell cycle or the fractional production rate of the lymphocytes. However, the calculated absolute production was reduced following ECIL, due to a decrease in the absolute number of cells present. The grain count over mitoses after ECIL was approximately one-half that found before ECIL.