Pregnant mice were treated on gestation Day 11 (E11) with a single dose of either hydroxyurea (HU, 250 mg/kg) or 5-bromo-2′deoxyuridine (BrdU, 500 mg/kg), or with a combination of the two agents. The dams were either allowed to go to term, when the fetuses were examined for cleft palate (CP) and digital anomalies, or killed 24 hr after the treatment. In the latter case, limbs from the embryos of control and treated dams were excised and cultured for 6 days in submerged culture. At the end of the culture period, the limb explants were stained for cartilage. The various cartilaginous components were subsequently analyzed using image analysis methods. CP was observed in 2.4 and 22.9% of the fetuses, respectively, after a single dose of HU or BrdU on E11. Simultaneous HU + BrdU treatment decreased the incidence of BrdU-induced CP to 3.6%, while treatment with BrdU 3 hr after HU resulted in 33.3% CP. In addition, syndactyly and ectrodactyly, not seen after the treatment with either HU or BrdU alone, were observed when the two agents were administered simultaneously, 1 hr apart or with a 3-hr delay. The teratogenic response was enhanced when limbs were cultured for 6 days. Digital anomalies were observed in the limb explants of BrdU-pretreated embryos; such abnormalities were not observed in vivo. Image analysis of cultured limb explants revealed that with HU-3 hr-BrdU pretreatment, the total limb area occupied by the long bones was increased at the cost of the paw area. However, no consistent changes in the shape or form of individual bones were observed. HU and BrdU given together produced a teratogenic response which was significantly different from that observed following the administration of HU or BrdU alone. This is considered to be due to an interference with the incorporation of BrdU in the DNA, since HU is known to block DNA synthesis. When HU was given before BrdU, the effects of BrdU were enhanced, probably due to the reported synchronizing action of HU on dividing cells. We also found that after a similar in utero exposure, the culture conditions themselves enhanced the frequency of teratogenic expression of BrdU.

A novel analog of dynorphin (1-13), D-Ala2,F5Phe4-dynorphin amide, was prepared and its pharmacological spectrum of activity was investigated. In a hot plate test on Swiss Webster and C57Bl mice, a 20 μg intracerebroventricular (icv) dose of the analog produced analgesia, which was greater in potency and duration than the parent dynorphin. This action of D-Ala2,F5Phe4-dynorphin amide was antagonized by the opiate receptor antagonist naloxone (2 mg/kg ip), administered either before or after the peptide. In addition to its analgesic action in mice, D-Ala2,F5Phe4-dynorphin amide produced a Straub tail and a catatonic-like state, both of which were also attenuated by naloxone. On the electrically-stimulated mouse vas deferens preparation, in vitro, D-Ala2,F5Phe4-dynorphin amide inhibited contractile activity and had an IC50 of 108.2 ± 34.7 nM (SEM), about 4-fold weaker than that of dynorphin. This action was also attenuated by naloxone. An icv dose of 150μg of D-Ala2,F5Phe4-dynorphin amide in mice, and a cumulative series of icv doses up to 2600μg in anesthetized rats, failed to produce a lethal effect. No pathological changes were observed in mouse liver kidney at 24 h after a 50 mg/kg dose of the peptide analog. In rats anesthetized with diallylbarbital (70 mg/kg ip) and urethane (280 mg/kg ip), D-Ala2,F5Phe4-dynorphin amide did not modify blood pressure, heart rate and respiratory rate. However, when mice were injected peripherally with single doses of D-Ala2,F5Phe4-dynorphin amide, convulsive episodes were produced, and lethal effects were observed with an LD50 of 60.0 mg/kg (95% confidence limits: 49.7-70.2 mg/kg) at 48 h. This action of D-Ala2,F5Phe4-dynorphin amide was not attenuated by naloxone (2.0 mg/kg, ip). Although analgesic and behavioral effects of D-Ala2,F5Phe4-dynorphin amide (e.g. Straub tail and catatonic-like state) are opiate-like, the lethal effect may be the consequence of actions of the peptide on non-opiate systems. Thus, the novel fluorinated dynorphin analog, D-Ala2,F5Phe4-dynorphin amide, may be a useful chemical tool for the study of opiate systems and their occasionally unanticipated biological or toxic actions.

Amounts of DNA in individual Feulgen-stained nuclei from squash preparations of ovaries and testes from wild-caught and laboratory-reared stocks of Poecilia spp. were determined with an integrating microdensitometer. The DNA content of primary spermatocytes (4C) at zygotene, pachytene, or at metaphase I (3.3-3.4 pg) was approximately twice that found in secondary spermatocytes (2C) and four times that found for young spermatids (1C). Rarely, mature sperm were found with 2C DNA amounts. Nuclei from follicular epithelium and oogonia from both bisexual and diploid unisexual fish contained about 1.6-1.7 pg DNA; whereas, the DNA content of primary oocyte nuclei was about 3.5-3.7 pg DNA, indicating that just one cycle of chromosomal replication had occurred in these cells during the period of DNA synthesis before the visible onset of meiotic prophase. Similar results were obtained for triploid unisexuals whose 6C primary oocyte nuclei contained 5.0-5.1 pg DNA, which was twice the DNA content of 3C oogonia and follicular epithelial cells (2.4-2.5 pg DNA). Autoradiographic studies, designed to monitor the incorporation of 3H-thymidine by oogonia and primary oocytes in vivo and in vitro, also showed that there is no additional synthesis of DNA during the course of meiotic prophase in these unisexual fish. Therefore, we conclude that apomixis, not endoreduplication, is the cytological basis of reproduction in Poecilia formosa and its related, triploid biotypes.

The number of sulfhydryl groups on the surface of intact erythrocytes from patients with polycythemia vera is significantly less (34%) than those from control subjects. Sulfhydryl groups were measured indirectly by reversibly blocking-SH groups with the thiol reagent, 6,6′-dithiodinicotinic acid, which forms stable mixed disulfides on the surface of erythrocytes. Glutathione was used to break the disulfides and release thione into the supernatant. Thione was then quantitated spectrophotometrically.

Focal lesions were placed in the retina of adult cats in order to denervate partially the laminae of the lateral geniculate nucleus (LGN). Retinogeniculate projections were assessed after survival times of from 5 days to 2 years by means of either reduced silver staining for degeneration or autoradiographic labelling. Filling of the lesion-denervated zones by 'sprouts' from the intact retinofugal fibers was not observed, even in the brains of animals with long-term lesions. It was concluded that the retinogeniculate projection in adult cat does not displat any significant ability to sprout into denervated regions.

The origin of hippocampal afferent projections was studied after horseradish peroxidase injections into the hippocampal formation. Labeled cells were found in the dorsal and ventrolateral aspects of the interpeduncular nucleus and in the ipsilateral portion of the nucleus reuniens thalami. In addition, neurons containing HRP were observed in the cortical, hypothalamic and brain stem areas reported by previous investigators.

A temperature-sensitive mutant of Escherichia coli affected in the alpha subunit of RNA polymerase has been investigated. Gene mapping and complementation experiments placed the mutation to temperature-sensitivity within the alpha operon at 72 min. on the bacterial chromosome. The rate of RNA synthesis in vivo and the accumulation of ribosomal RNA were significantly reduced in the mutant at 44°C. The thermostability at 44°C of the purified holoenzyme from mutant cells was about 20% of that of the normal enzyme. Assays with T7 DNA as a template showed that the fraction of active enzyme competent for transcription was reduced as a function of assay temperature but that initiation and elongation were not significantly affected by the alpha mutation. A major effect on the fidelity of transcription was observed with the mutant enzyme, with misincorporation on two different templates stimulated about 4 fold at 37°C. The role of the alpha dimer in the structure and function of RNA polymerase is discussed.

The Purkinje target cells for noradrenergic fibers originating in the locus coeruleus are considered to be of importance in the regulation of noradrenergic input to the cerebellum. The availability of a mouse mutant, Purkinje cell degeneration provides a non-surgical means for studying cellular regulation of innervation. Using a glyoxylic acid histofluorescent method for visualizing noradrenergic fibers, the observations have been made that the density of green histofluorescent neuntes is markedly increased in both the granule and molecular layers of the cerebellum of Purkinje cell degeneration mice, following spontaneous degeneration of the Purkinje cells. However, because of tissue shrinkage, tissue concentration of norepinephrine also increases, but total tissue content of norepinephrine is unchanged in whole cerebellum and outer cerebellar cortex. These findings indicate that the relative number of noradrenergic afferents to the molecular layer of the cerebellum is not reduced following spontaneous degeneration of Purkinje cells. Therefore, Purkinje target cells do not appear to be essential for maintenance of afferent inputs in mature cerebellum.

Choline acetyltransferase activity and localization of acetylcholinesterase and [3H]quinuclidinyl benzilate binding sites (muscarinic receptors) in rat facial nuclei were examined 2 weeks after right facial nerve transection or sham control surgery. Choline acetyltransferase activity in the right facial nucleus of nerve-transected rats was only one-third of that in the left nucleus. Histochemical observations revealed loss of acetylcholinesterase from most motoneurons and neuropil of the right facial nucleus after axotomy. Autoradiographic grains, marking muscarinic receptors, were likewise depleted substantially from this region. Facial nuclei of control animals were identical with respect to all of these neurochemical measures and undistinguishable from the left facial nucleus of nerve-transected rats. Cholinergic enzymes are known to be synthesized by motoneurons, but the source of muscarinic receptors in the facial nucleus is not known. Since all three proteins are depleted from the facial nucleus after axotomy of motoneurons, it is concluded that these cells produce cholinergic enzymes and muscarinic receptors. Synthesis of muscarinic receptors by facial motoneurons could indicate these neurons are cholinoceptive. Axotomy should be a useful tool for determining which other neurotransmitter receptors are produced by facial motoneurons and efferent neurons in other cranial nerve nuclei.

Three pairs of related macrolide antibiotics, differing at the 11,12 position of the macrolactone ring, were compared for effects on growth rate, cell viability, protein synthesis, and 50S ribosomal subunit formation in Staphylococcus aureus cells. For each parameter measured, the 11,12 carbonate-derivatized compound was more inhibitory compared with the corresponding 11,12-hydroxy antibiotic. Substitution at the 3-position of the ring was also important in the relative inhibition observed. The degree of inhibition found in two different growth media was proportional to the generation time of the cells. Inhibition of both protein synthesis and 50S subunit formation by each drug correlated well with the inhibition of cell viability. The results indicate that closure of the 11,12-hydroxyl groups in macrolide antibiotics with a carbonate substitution generates a more effective antimicrobial agent.