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141.
Maturation and timing of spawning in relation to temperature were studied in a local Atlantic herring Clupea harengus population inhabiting a small semi‐enclosed ecosystem (7 km2) separated from the larger outer fjord system by narrow sills on the west coast of Norway. Ambient temperatures varied annually up to 4° C during both the pre‐spawning and spawning periods from February to April, but without affecting the spawning time. Instead, the timing of spawning was found to be related to thermal stratification in response to spring warming, which occurred about the same time every year regardless of initial temperatures. 相似文献
142.
dos Santos Schmidt Thassya C. Hay Doug E. Sundby Svein Devine Jennifer A. Óskarsson Guðmundur J. Slotte Aril Wuenschel Mark J. Lajus Dmitry Johannessen Arne van Damme Cindy J. G. Bucholtz Rikke H. Kjesbu Olav S. 《Reviews in Fish Biology and Fisheries》2021,31(3):685-708
Reviews in Fish Biology and Fisheries - Life-history traits of Pacific (Clupea pallasii) and Atlantic (Clupea harengus) herring, comprising both local and oceanic stocks subdivided into... 相似文献
143.
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145.
Effects of l-Methyl-4-Phenyl-l,2,3,6-Tetrahydropyridine in the Dog: Effect of Pargyline Pretreatment 总被引:2,自引:2,他引:0
J. N. Johannessen C. C. Chiueh J. P. Bacon N. A. Garrick R. S. Burns V. K. Weise I. J. Kopin J. E. Parisi S. P. Markey 《Journal of neurochemistry》1989,53(2):582-589
Adult beagle dogs of either sex were injected with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-HCl (2.5 mg/kg, i.v.) alone or after pretreatment with pargyline (5.0 mg/kg, s.c., twice), with pargyline alone, or were uninjected. Groups were killed 2 h, 3 weeks, or 3 months after injection, and several brain areas were assayed for biogenic amines and their synthetic and degradative enzymes. MPTP caused a massive and permanent loss of striatal dopamine, tyrosine hydroxylase, and 3,4-dihydroxyphenylalanine decarboxylase activities and the loss of cells within the substantia nigra pars compacta. Dopamine and norepinephrine also were depleted to various degrees in cortex, olfactory bulb, and hypothalamus; however, dopamine beta-hydroxylase activity in cortex was normal. There was no cell loss in the ventral tegmental area or locus ceruleus. The activities of monoamine oxidase (MAO)-A and MAO-B in cortex and caudate were not affected by MPTP. Despite a permanent loss of the nigrostriatal system, the dogs exhibited only a transient hypokinesia lasting 1-2 weeks. Pargyline pretreatment prevented the loss of striatal dopamine and cells from the substantia nigra, but did not prevent a prolonged but reversible decrease in the concentration of dopamine metabolites. It is argued that this apparent inhibition of MAO is due not to suicide inactivation of the enzyme by MPTP, but to reversible inhibition by accumulation of the pyridinium metabolite, 1-methyl-4-phenylpyridinium, selectivity in aminergic terminals. 相似文献
146.
Tanmay?S. Chavan Hyunbum Jang Lyuba Khavrutskii Sherwin?J. Abraham Avik Banerjee Benjamin?C. Freed Liv Johannessen Sergey?G. Tarasov Vadim Gaponenko Ruth Nussinov Nadya?I. Tarasova 《Biophysical journal》2015,109(12):2602-2613
Ras proteins are small GTPases that act as signal transducers between cell surface receptors and several intracellular signaling cascades. They contain highly homologous catalytic domains and flexible C-terminal hypervariable regions (HVRs) that differ across Ras isoforms. KRAS is among the most frequently mutated oncogenes in human tumors. Surprisingly, we found that the C-terminal HVR of K-Ras4B, thought to minimally impact the catalytic domain, directly interacts with the active site of the protein. The interaction is almost 100-fold tighter with the GDP-bound than the GTP-bound protein. HVR binding interferes with Ras-Raf interaction, modulates binding to phospholipids, and slightly slows down nucleotide exchange. The data indicate that contrary to previously suggested models of K-Ras4B signaling, HVR plays essential roles in regulation of signaling. High affinity binding of short peptide analogs of HVR to K-Ras active site suggests that targeting this surface with inhibitory synthetic molecules for the therapy of KRAS-dependent tumors is feasible. 相似文献
147.
Jostein Gohli Erica H. Leder Eduardo Garcia‐del‐Rey Lars Erik Johannessen Arild Johnsen Terje Laskemoen Magnus Popp Jan T. Lifjeld 《Molecular ecology》2015,24(1):180-191
A common challenge in phylogenetic reconstruction is to find enough suitable genomic markers to reliably trace splitting events with short internodes. Here, we present phylogenetic analyses based on genomewide single‐nucleotide polymorphisms (SNPs) of an enigmatic avian radiation, the subspecies complex of Afrocanarian blue tits (Cyanistes teneriffae). The two sister species, the Eurasian blue tit (Cyanistes caeruleus) and the azure tit (Cyanistes cyanus), constituted the out‐group. We generated a large data set of SNPs for analysis of population structure and phylogeny. We also adapted our protocol to utilize degraded DNA from old museum skins from Libya. We found strong population structuring that largely confirmed subspecies monophyly and constructed a coalescent‐based phylogeny with full support at all major nodes. The results are consistent with a recent hypothesis that La Palma and Libya are relic populations of an ancient Afrocanarian blue tit, although a small data set for Libya could not resolve its position relative to La Palma. The birds on the eastern islands of Fuerteventura and Lanzarote are similar to those in Morocco. Together they constitute the sister group to the clade containing the other Canary Islands (except La Palma), in which El Hierro is sister to the three central islands. Hence, extant Canary Islands populations seem to originate from multiple independent colonization events. We also found population divergences in a key reproductive trait, viz. sperm length, which may constitute reproductive barriers between certain populations. We recommend a taxonomic revision of this polytypic species, where several subspecies should qualify for species rank. 相似文献
148.
Primary malignant fibrous histiocytoma of the breast 总被引:1,自引:0,他引:1
Clinical, light microscopic, electron microscopic and immunocytochemical features of 4 cases (3 women and 1 man) of primary malignant fibrous histiocytoma (MFH) of the breast are presented. The literature is reviewed and the diagnosis and treatment discussed. The good outcome is stressed and local excision or simple mastectomy recommended as appropriate treatment. 相似文献
149.
Evolution of antibiotic resistance genes: the DNA sequence of a kanamycin resistance gene from Staphylococcus aureus 总被引:14,自引:0,他引:14
The kanamycin resistance gene from Staphylococcus aureus has been sequenced
and its structure compared with similar genes isolated from Streptomyces
fradiae and from two transposons, Tn5 and Tn903, originally isolated from
Klebsiella pneumoniae and Salmonella typhimurium, respectively. The genes
are all homologous but, since their common ancestor, have undergone
extensive divergence, with more than 43% divergence between the closest
pair. The phylogeny of the genes cannot be made congruent to the phylogeny
of the taxa from which they were isolated without requiring rather
improbable differences in rates. One is therefore led to conclude that
there have been multiple occurrences of gene transfer between these
species. Thus, although they are homologous, they are neither orthologous
nor paralogous. It is suggested that homologous genes of this type be
called xenologous.
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