排序方式: 共有55条查询结果,搜索用时 31 毫秒
41.
Female mate preference based on male orange spot patterns in the feral guppy <Emphasis Type="Italic">Poecilia reticulata</Emphasis> in Japan 总被引:2,自引:2,他引:0
Kenji?Karinokkarino@u-gakugei.ac.jp" title="KK kkarino@u-gakugei.ac.jp" itemprop="email" data-track="click" data-track-action="Email author" data-track-label="">Email author Shinya?Shinjo 《Ichthyological Research》2004,51(4):316-320
It is known that females prefer males with larger and/or brighter orange spots in many populations of the guppy Poecilia reticulata. However, female preference for male orange spots varies among populations and changes within several years when they are introduced into new habitats with different environment. Guppies were introduced into Okinawa, Japan, more than 20 years ago and were subjected to natural and sexual selection for a long period. The female preference for orange spot patterns of males was examined by the dichotomous choice experiment for a feral guppy population of the Hiji River, Okinawa. We chose full-sibling males as a pair of stimulus males that were simultaneously presented to a test female, because sibling males should resemble each other. To create different orange spot patterns between stimulus males, one male of the stimulus male pair was fed carotenoid-supplement food such as algae and another male was fed low-carotenoid food. High-carotenoid-treatment males showed not only brighter coloration of orange spots but also larger spots than other males as a result of this dietary-manipulation. In the dichotomous choice experiment, females preferred the high-carotenoid-treatment males. In addition, logistic regression analysis clarified that brighter coloration of male orange spots was the most important factor for female mate preference. This finding suggests indirect benefits of female preference for male orange spot patterns if the male foraging ability for algae were heritable. 相似文献
42.
Astringency of aqueous solutions of phenolic compounds (grape seed tannins,
tannic acid, catechin and gallic acid) increased upon addition of citric
acid, whereas the astringency of alum was reduced. Astringency of alum was
decreased equivalently by addition of equi-sour levels of lactic acid,
citric acid or hydrochloric acid. The difference between alum and the
phenolic compounds is speculated to result from chemical modifications
affecting binding of the astringents with oral proteins rather than
cognitive differences. Chelation of the aluminum ion in alum by acids
reduces its availability for interacting with salivary proteins or
epithelial proteins. In contrast, the increased astringency produced upon
acidification of phenolic compounds is speculated to result from the pH
driven increase in the affinity of the phenols for binding with proteins.
These results suggest that alum cannot be used interchangeably with
phenolic astringents in psychophysical studies.
相似文献
43.
Wetra Yandi Sophie Mieszkin Alessio di Fino Pierre Martin-Tanchereau Maureen E. Callow James A. Callow 《Biofouling》2016,32(6):609-625
The resistance of charged polymers to biofouling was investigated by subjecting cationic (PDMAEMA), anionic (PSPMA), neutral (PHEMA-co-PEG10MA), and zwitterionic (PSBMA) brushes to assays testing protein adsorption; attachment of the marine bacterium Cobetia marina; settlement and adhesion strength of zoospores of the green alga Ulva linza; settlement of barnacle (Balanus amphitrite and B. improvisus) cypris larvae; and field immersion tests. Several results go beyond the expected dependence on direct electrostatic attraction; PSPMA showed good resistance towards attachment of C. marina, low settlement and adhesion of U. linza zoospores, and significantly lower biofouling than on PHEMA-co-PEG10MA or PSBMA after a field test for one week. PDMAEMA showed potential as a contact-active anti-algal coating due to its capacity to damage attached spores. However, after field testing for eight weeks, there were no significant differences in biofouling coverage among the surfaces. While charged polymers are unsuitable as antifouling coatings in the natural environment, they provide valuable insights into fouling processes, and are relevant for studies due to charging of nominally neutral surfaces. 相似文献
44.
45.
Effect of self-association on the structural organization of partially folded proteins: inactivated actin 总被引:1,自引:0,他引:1
下载免费PDF全文
![点击此处可从《Biophysical journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
IM Kuznetsova AG Biktashev SY Khaitlina KS Vassilenko KK Turoverov VN Uversky 《Biophysical journal》1999,77(5):2788-2800
The propensity to associate or aggregate is one of the characteristic properties of many nonnative proteins. The aggregation of proteins is responsible for a number of human diseases and is a significant problem in biotechnology. Despite this, little is currently known about the effect of self-association on the structural properties and conformational stability of partially folded protein molecules. G-actin is shown to form equilibrium unfolding intermediate in the vicinity of 1.5 M guanidinium chloride (GdmCl). Refolding from the GdmCl unfolded state is terminated at the stage of formation of the same intermediate state. An analogous form, known as inactivated actin, can be obtained by heat treatment, or at moderate urea concentration, or by the release of Ca(2+). In all cases actin forms specific associates comprising partially folded protein molecules. The structural properties and conformational stability of inactivated actin were studied over a wide range of protein concentrations, and it was established that the process of self-association is rather specific. We have also shown that inactivated actin, being denatured, is characterized by a relatively rigid microenvironment of aromatic residues and exhibits a considerable limitation in the internal mobility of tryptophans. This means that specific self-association can play an important structure-forming role for the partially folded protein molecules. 相似文献
46.
Di Gioia S Rejman J Carrabino S De Fino I Rudolph C Doherty A Hyndman L Di Cicco M Copreni E Bragonzi A Colombo C Boyd AC Conese M 《Biomacromolecules》2008,9(3):859-866
Efficient gene transfer to the airways by nonviral vectors is a function of different parameters, among which the size and the charge of the transfecting particles. The aim of this study was to determine the transfection efficiency of polyethylenimine (PEI)/albumin polyplexes in ex vivo and in vivo models of respiratory epithelium and to correlate it with biophysical characteristics of the particles. Complexes were obtained by adding different amounts of human serum albumin (HSA) to PEI polyplexes preformed in saline. The presence of HSA caused the formation of bigger and more negative polyplexes and increased PEI transfection efficiency in primary respiratory epithelial cells by 4-6-fold. For in vivo administration to the lung, PEI polyplexes were formed in water and optimized with respect to the N/ P ratio. PEI/pC-Luc complexes gave the highest luciferase expression at N/ P 15 when administered through the trachea. At this N/ P ratio, the size and the surface charge of albumin-containing polyplexes were not different as compared with plain PEI polyplexes. Formulation of PEI polyplexes in the presence of HSA or murine serum albumin (MSA) resulted in a 2-fold increase in luciferase expression. In mice treated with PEI or PEI/MSA polyplexes containing the nuclear beta-gal gene, X-gal staining revealed that transfected cells localized at the bronchiolar epithelium and that PEI/MSA transfected four times as many cells as PEI ( p < 0.05). Finally, double administration of PEI/MSA polyplexes resulted in a further enhancement of transfection of the lung. Our data show that serum albumin enhances PEI-mediated gene transfer to airway epithelial cells in vivo, likely facilitating the uptake of polyplexes, and indicate that this formulation would fulfill the requirement of repeated administration, as necessary in chronic lung diseases like cystic fibrosis. 相似文献
47.
The connectivity diagram of neocortical circuits is still unknown, and there are conflicting data as to whether cortical neurons are wired specifically or not. To investigate the basic structure of cortical microcircuits, we use a two-photon photostimulation technique that enables the systematic mapping of synaptic connections with single-cell resolution. We map the inhibitory connectivity between upper layers somatostatin-positive GABAergic interneurons and pyramidal cells in mouse frontal cortex. Most, and sometimes all, inhibitory neurons are locally connected to every sampled pyramidal cell. This dense inhibitory connectivity is found at both young and mature developmental ages. Inhibitory innervation of neighboring pyramidal cells is similar, regardless of whether they are connected among themselves or not. We conclude that local inhibitory connectivity is promiscuous, does not form subnetworks, and can approach the theoretical limit of a completely connected synaptic matrix. 相似文献
48.
Purified chloroplast tRNAs were isolated fromPisum sativum leaves and radioactively labeled at their 3′ end using tRNA nucleotidyl transferase and α32P-labeled CTP. Pea ctDNA was fragmented using a number of restriction endonucleases and hybridized with thein vitro labeled chloroplast tRNAs by DNA transfer method. Genes for tRNAs have been found to be dispersed throughout the chloroplast
genome. A closer analysis of the several hybrid regions using recombinant DNA plasmids have shown that tRNA genes are localized
in the chloroplast genome in both single and multiple arrangements. Two dimensional gel electrophoresis of total ct tRNA have
identified 36 spots. All of them have been found to hybridize withPisum sativum ctDNA. Using recombinant clones, 30 of the tRNA spots have been mapped inPisum sativum ctDNA. 相似文献
49.
Age-stiffening of ocular tissues is statistically linked to glaucoma in the elderly. In this study, the effects of age-stiffening on the lamina cribrosa, the primary site of glaucomatous nerve damages, were modeled using computational finite element analysis. We showed that glaucomatous nerve damages and peripheral vision loss behavior can be phenomenologically modeled by shear-based damage criterion. Using this damage criterion, the potential vision loss for 30 years old with mild hypertension of 25mmHg intraocular pressure (IOP) was estimated to be 4%. When the IOP was elevated to 35mmHg, the potential vision loss rose to 45%; and age-stiffening from 35 to 60 years old increased the potential vision loss to 52%. These results showed that while IOP plays a central role in glaucomatous damages, age-stiffening facilitates glaucomatous damages and may be the principal factor that resulted in a higher rate of glaucoma in the elderly than the general population. 相似文献
50.
Andrea Raimondi Giorgia Girotti Gian Andrea Blengini Debora Fino 《The International Journal of Life Cycle Assessment》2012,17(8):987-996