Electrophoretic study of cutthroat trout populations in Utah

Thirty - nine Utah streams were sampled for cutthroat trout. Of these, 31 contain cutthroat or cutthroat / rainbow hybrid populations. By using starch gel electrophoresis, these populations were segregated into three groups. One group consisted predominately of fish from the Sevier River (of the Bonneville Basin) and Colorado drainages. A second was primarily populations from the Bear River Drainage (Bonneville Basin) as well as some scattered populations along the Wasatch Front (Bonneville Basin). The third consisted of Wasatch Front populations and populations that have hybridized with rainbow trout. Since different subspecies of cutthroat trout are native to the Colorado and Bonneville drainages, one would expect the populations from within the Bonneville Basin to be more similar to one another and less similar to the Colorado River populations. That this did not occur raises questions concerning the evolutionary relationships of the subspecies and the populations. It is clear that at least a northern (Bear River) and southern (Sevier River) form of the Bonneville cutthroat exists. The Wasatch Front may represent an intermediate zone where these two forms intergrade.         

Influence of castration and testosterone replacement on hypothalamic tyrosine hydroxylase activity in the rat.

Hypothalamic tyrosine hydroxylase (TH) activity of castrate rats is modulated by testosterone propionate (TP) in vivo. Kinetic studies revealed that both Vmax and Km were virtually unaltered for substrate tyrosine in the presence of an excess of DMPH4 cofactor. TP replacement to castrate rats increased the Km for added DMPH4 cofactor, while Vmax decreased. These results suggest that TP decreases TH activity of castrate rats by inhibiting the enzyme-reduced pteridine cofactor complex.     

Reproductive cycle of the Belding ground squirrel ( Spermophilus beldingi beldingi ): seasonal and age differences

The reproductive cycle in Belding ground squirrels was studied in the Sierra Nevada Mountains at two locations, one at 2,100 m elevation, the other at 3,000 m. Adults emerged from hibernation completely prepared physiologically for reproduction. Males tended to emerge slightly ahead of females and yearlings tended to emerge later than adults. Yearling females were fertile but produced smaller litters than adults, 4.48 vs. 6.31. Yearling males were infertile. They exhibited a slight seasonal cycle in testicular growth but did not reach sexual maturity. Testicular growth and spermatogenesis were incipient in many adults and in yearlings prior to hibernation.       

Absence of a robust innate immune response in rat neurons facilitates persistent infection of Borna disease virus in neuronal tissue

Borna disease virus (BDV) persistently infects neurons of the central nervous system of various hosts, including rats. Since type I IFN-mediated antiviral response efficiently blocks BDV replication in primary rat embryo fibroblasts, it has been speculated that BDV is not effectively sensed by the host innate immune system in the nervous system. To test this assumption, organotypical rat hippocampal slice cultures were infected with BDV for up to 4 weeks. This resulted in the secretion of IFN and the up-regulation of IFN-stimulated genes. Using the rat Mx protein as a specific marker for IFN-induced gene expression, astrocytes and microglial cells were found to be Mx positive, whereas neurons, the major cell type in which BDV is replicating, lacked detectable levels of Mx protein. In uninfected cultures, neurons also remained Mx negative even after treatment with high concentrations of IFN-α. This non-responsiveness correlated with a lack of detectable nuclear translocation of both pSTAT1 and pSTAT2 in these cells. Consistently, neuronal dissemination of BDV was not prevented by treatment with IFN-α. These data suggest that the poor innate immune response in rat neurons renders this cell type highly susceptible to BDV infection even in the presence of exogenous IFN-α. Intriguingly, in contrast to rat neurons, IFN-α treatment of mouse neurons resulted in the up-regulation of Mx proteins and block of BDV replication, indicating species-specific differences in the type I IFN response of neurons between mice and rats.     

Summer habitat use and selection by female Sage Grouse ( Centrocercus urophasianus ) in Oregon

Cover types and vegetative characteristics (e.g., grasses, forbs, shrubs) used by female Sage Grouse ( Centrocercus urophasianus ) during summer were compared with available habitat on two study areas in southeastern Oregon. Broodless hens, which constituted 114 of the 125 (91%) radio-marked hens studied, selected big ( Artemisia tridentata ) subspp.) and low sagebrush ( A. arbuscular ) cover types at both study areas. At Hart Mountain, broodless hens did not select specific vegetative characteristics within cover types. However, at Jackass Creek, forb cover was greater ( P = .004) at broodless hen sites than at random locations. Differences in habitat use by broodless hens between study areas were associated with differences in forb availability. Broodless hens used a greater diversity of cover types than hens with broods. Broodless hens gathered in flocks and remained separate from but near hens with broods during early summer. By early July broodless hens moved to meadows while hens with broods remained in upland habitats.     

Mathematics, technics, and courtly life in Late Renaissance Urbino

The present article seeks to provide an overview of the general characteristics of the cultural and scientific climate in the Duchy of Urbino. Three of the Duchy’s milieus seem to have been particularly important for scholars who were engaged in the study of mathematics: the so-called “School of Urbino”, the environment of the court, and the world of the technicians and engineers. While the Urbino School has already been the object of previous studies, the other two milieus and their effect on the mathematicians’ work have been rather neglected and are, consequently, addressed here. The paper’s final section presents some documents that attest the importance of Renaissance scholars’ interaction with these environments to their actual scientific activity, taking the case of Guidobaldo dal Monte as an example.     

HCN2 channels in local inhibitory interneurons constrain LTP in the hippocampal direct perforant path

Neuronal hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are known to modulate spontaneous activity, resting membrane potential, input resistance, afterpotential, rebound activity, and dendritic integration. To evaluate the role of HCN2 for hippocampal synaptic plasticity, we recorded long-term potentiation (LTP) in the direct perforant path (PP) to CA1 pyramidal cells. LTP was enhanced in mice carrying a global deletion of the channel (HCN2^−/−) but not in a pyramidal neuron-restricted knockout. This precludes an influence of HCN2 located in postsynaptic pyramidal neurons. Additionally, the selective HCN blocker zatebradine reduced the activity of oriens-lacunosum moleculare interneurons in wild-type but not HCN2^−/− mice and decreased the frequency of spontaneous inhibitory currents in postsynaptic CA1 pyramidal cells. Finally, we found amplified LTP in the PP of mice carrying an interneuron-specific deletion of HCN2. We conclude that HCN2 channels in inhibitory interneurons modulate synaptic plasticity in the PP by facilitating the GABAergic output onto pyramidal neurons.     

Drosophila genes Posterior Sex Combs and Suppressor two of zeste encode proteins with homology to the murine bmi-1 oncogene.

The Polycomb group (Pc-G) genes are needed to maintain expression patterns of the homeotic selector genes of the Antennapedia (Antp-C) and bithorax (bx-C) complexes, and hence for the maintenance of segmental determination. We report the predicted protein sequence of the Pc-G gene Posterior Sex Combs (Psc), and of the neighbouring and related gene Suppressor two of zeste (Su(z)2). Both genes encode large proteins that contain a 200 amino-acid domain identical over 37.4% that is also conserved in the murine oncogene bmi-1. At the amino terminus of this domain is a cysteine-rich sequence that has been proposed as a novel type of zinc finger.     

Evidence for a different site of action of phenoxybenzamine and desmethylimipramine on the catecholamine uptake system

Resumen El tratamiento con fenoxibenzamina o desmetilimipramina da lugar a una potenciación irreversible de las respuestas a noradrenalina, en la aurícula aislada de cobayo. La presencia de tiramina durante el tratamiento previene dicha potenciación cuando se utiliza fenoxibenzamina, mientras que no la modifica en el caso de la desmetilimipramina     

Phorbol ester and diacylglycerol induce protein phosphorylation at tyrosine

The phorbol ester 12-O-tetradecanoyl-phorbol-13-acetate (TPA) is an efficient tumour promoter in vivo. In vitro, TPA activates the phospholipid- and Ca2+-dependent protein kinase, kinase C. This activation is believed to reflect the structural similarity between TPA and diacylglycerol, the endogenous protein kinase C activator which is produced in vivo by hydrolysis of phosphatidylinositol (reviewed in ref. 3). Protein kinase C phosphorylates protein substrates at serine and threonine residues in vitro. The effects of TPA on cultured fibroblasts--including enhanced hexose uptake, disruption of actin stress fibres and growth stimulation--are very similar to those induced by certain retrovirus transforming proteins and by peptide growth factors such as epidermal growth factor (EGF), platelet-derived growth factor (PDGF) and multiplication-stimulating activity (MSA). These transforming proteins and mitogenic agents seem to act by inducing tyrosine-specific protein phosphorylation. Such observations suggested that some of the effects of TPA in vivo may be mediated by protein phosphorylation at tyrosine residues. A 42,000-molecular weight (42 K) polypeptide was previously shown to be phosphorylated at tyrosine in cells transformed by avian sarcoma viruses and in cells stimulated by EGF, PDGF or MSA (J. Cooper, personal communication and refs 11 and 12; this polypeptide was originally designated 43 K or spot n in ref. 10). We show here that this polypeptide also becomes phosphorylated at tyrosine in cells treated with TPA. Furthermore, exogenously added diacylglycerol likewise stimulates the phosphorylation of this protein at tyrosine.