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271.
From old organisms to new molecules: integrative biology and therapeutic targets in accelerated human ageing 总被引:6,自引:1,他引:5
Understanding the basic biology of human ageing is a key milestone in attempting to ameliorate the deleterious consequences of old age. This is an urgent research priority given the global demographic shift towards an ageing population. Although some molecular pathways that have been proposed to contribute to ageing have been discovered using classical biochemistry and genetics, the complex, polygenic and stochastic nature of ageing is such that the process as a whole is not immediately amenable to biochemical analysis. Thus, attempts have been made to elucidate the causes of monogenic progeroid disorders that recapitulate some, if not all, features of normal ageing in the hope that this may contribute to our understanding of normal human ageing. Two canonical progeroid disorders are Werner's syndrome and Hutchinson-Gilford progeroid syndrome (also known as progeria). Because such disorders are essentially phenocopies of ageing, rather than ageing itself, advances made in understanding their pathogenesis must always be contextualised within theories proposed to help explain how the normal process operates. One such possible ageing mechanism is described by the cell senescence hypothesis of ageing. Here, we discuss this hypothesis and demonstrate that it provides a plausible explanation for many of the ageing phenotypes seen in Werner's syndrome and Hutchinson-Gilford progeriod syndrome. The recent exciting advances made in potential therapies for these two syndromes are also reviewed. 相似文献
272.
tRNase Z: the end is not in sight 总被引:1,自引:0,他引:1
Although the enzyme tRNase Z has only recently been isolated, a plethora of data has already been acquired concerning the
enzyme. tRNase Z is the endonuclease that catalyzes the removal of the tRNA 3′ trailer, yielding the mature tRNA 3′ end ready
for CCA addition and aminoacylation. Another substrate cleaved by tRNase Z is the small chromogenic phosphodiester bis(p-nitrophenyl)phosphate (bpNPP), which is the smallest tRNase Z substrate known so far. Hitherto the biological function as
tRNA 3′-end processing enzyme has been shown only in one prokaryotic and one eukaryotic organism, respectively. This review
summarizes the present information concerning the two tRNase Z substrates pre-tRNA and bpNPP, as well as the metal requirements
of tRNase Z enzymes.
Received 29 March 2007; received after revision 15 May 2007; accepted 21 May 2007 相似文献
273.
Beyond their role in replication and chromosome end capping, telomeres are also thought to function in meiotic chromosome pairing, meiotic and mitotic chromosome segregation as well as in nuclear organization. Observations in both somatic and meiotic cells suggest that the positioning of telomeres within the nucleus is highly specific and believed to be dependent mainly on telomere interactions with the nuclear envelope either directly or through chromatin interacting proteins. Although little is known about the mechanism of telomere clustering, some studies show that it is an active process. Recent data have suggested a regulatory role for telomere chromatin structure in telomere movement. This review will summarize recent studies on telomere interactions with the nuclear matrix, telomere chromatin structure and factors that modify telomere chromatin structure as related to regulation of telomere movement. 相似文献
274.
Cryptic subarctic diversity: a new bumblebee species from the Yukon and Alaska (Hymenoptera: Apidae)
Paul H. Williams Sydney G. Cannings Cory S. Sheffield 《Journal of Natural History》2016,50(45-46):2881-2893
It is nearly 90 years since a bumblebee species has been described for the first time from Canada or the USA that was previously unrecognised by science. We describe and illustrate Bombus(Alpinobombus) kluanensis sp. nov. and begin to map its distribution. This species was discovered through analysis of Cytochrome c Oxidase subunit I barcodes and had been unsuspected on the basis of morphological and colour characteristics. So far, 247 female specimens considered to belong to this species are known from the subarctic mountains associated with the Denali Fault running from the Alaska Range (Alaska, USA) to Kluane in the Saint Elias Mountains (Yukon, Canada). A checklist of all species of the subgenus Alpinobombus worldwide is provided.
http://zoobank.org/urn:lsid:zoobank.org:pub:78D524DD-FFBA-4BC4-8D39-3EF4F6BDD39E 相似文献
275.
276.
Celso O. Azevedo Simon van Noort David G. Notton 《Journal of Natural History》2018,52(23-24):1537-1549
Holepyris semiruber Kieffer is redescribed and illustrated based on freshly collected specimens. Holepyris semiruber var. striatipleura Kieffer is considered a colour variant of this species and therefore a junior synonym of H. semiruber syn. nov. This species is transferred to Disepyris, D. semiruber (Kieffer) comb. nov., based on the possession of a short 2r-rs&Rs vein in the fore wing and presence of long flat spine-shaped setae on the outer (posterior) surface of the protarsi. The male is described for the first time from new specimens collected in South Africa. This species is recorded for the first time from Namibia and Zimbabwe. All photographs are available on www.waspweb.org. 相似文献
277.
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279.
Lily Campbell Sarah E. Dudas Francis Juanes Travis G. Gerwing 《Journal of Natural History》2020,54(15-16):919-945
ABSTRACT The Skeena River estuary supports commercial and culturally important salmon fisheries. However, considerable development has occurred in the area, and more has been proposed. If anthropogenic development degrades this critical habitat, the Skeena salmon run, that every year contributes $110 million to local economies, may be negatively impacted. Benthic invertebrates are common indicator species, as they often respond to disturbances before commercial species, warning of potential impacts. Unfortunately, invertebrates in the Skeena estuary have not been extensively studied, and we lack the detailed understanding of their community structure and dynamics for them to serve as indicator species in this region. Therefore, present conditions of the Skeena estuary are established here (invertebrate community, sediment conditions and food availability), in order to provide the data required both to anticipate changes associated with potential anthropogenic disturbances and to detect changes in this system if development occurs. 相似文献
280.
Thomas Görnitz 《Foundations of Science》2018,23(3):475-510
Our interest focusses on the idea, that consciousness is a powerful acting entity. Up to now there does not exist a scientific concept for this idea. This is not due to problems within the field of psychology or brain research, but rather in resisting theories of modern physics. That is, why we have to search for a solution in the field of physics. A solution can be found in a new understanding of the basics of physical theory. That could be given by abstract and absolute quantum bits of information (AQI bits). To avoid the popular misunderstanding of “information” as “meaningful” it was necessary to find a new word for the free-of-meaning AQI bits: the AQI bits establish a quantum pre-structure termed “Protyposis” (Greek: “pre-formation”), out of which real objects can be formed, starting from energetical and material elementary particles. The Protyposis AQI bits provide a pre-structure for all entities in natural sciences. They are the basic entities, whereof the physical nature of the brain, on the one hand, and the mental nature of consciousness, on the other hand, were formed during the cosmological and the following biological evolution. A deeper understanding of quantum structures may help to overcome the resistance against quantum theory in the field of brain research and consciousness. The key for an understanding is the concept of Protyposis, which means an abstract quantum information free of any definite meaning. With the AQI bits of the Protyposis, both, massless and massive quantum particles can be constructed. Even quantum information with special meanings, in example grammatically formulated thoughts, eventually could be explained. As long as the fundamental basis of quantum theory is misunderstood as being formed by a manifold of some small objects like atoms, quarks, or strings, the problem of understanding consciousness has no solution. If instead we understand quantum theory as based on truly simple quantum structures, there would be no longer fundamental problems for an understanding of consciousness. 相似文献