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411.
Growth,photosynthetic efficiency,and biochemical composition of Tetraselmis suecica F&M‐M33 grown with LEDs of different colors 下载免费PDF全文
412.
Keirith A. Snyder Robert Monnar Simon R. Poulson Peter Hartsough Franco Biondi 《Trees - Structure and Function》2010,24(3):585-595
Diurnal fluctuations of leaf water isotope ratios (δ18O and δD) were measured for Jeffrey (Pinus jeffreyi Balf.) and lodgepole (Pinus contorta Douglas ex Louden) pine. Two trees per species were sampled every few hours on 15–16 October 2005 and 19–20 June 2006. Diurnal
gas exchange was measured during the summer sampling. In fall 2005, leaf water δ18O ranged from 0.7 to 9.0‰, and leaf water δD ranged from −70 to −50‰. In summer 2006, leaf water δ18O ranged from 7.7 to 20.7‰, and leaf water δD ranged from −61 to −24‰. Diurnal variation of leaf water isotope values typically
reached a maximum in early afternoon, began decreasing around midnight, and reached a minimum in mid-morning. Both periods
showed a high degree of enrichment relative to source water, with leaf water–source water enrichments ranging up to 37.8‰
for δ18O, and up to 95‰ for δD. Leaf water enrichment varied by season with summer enrichment being greater than fall enrichment.
A steady-state model (i.e., modified Craig–Gordon modeling) for leaf water isotope compositions did not provide a good fit
to measured values of leaf water. In summer, a non-steady state model provided a better fit to the measured data than the
steady-state model. Our findings demonstrate substantial leaf water enrichment above source water and diurnal variations in
the isotopic composition of leaf water, which has application to understanding short-term variability of atmospheric gases
(water vapor, CO2, O2), climate studies based on the isotopic composition of tree rings, and ecosystem water fluxes. 相似文献
413.
Barbara Biondi Dante Goldin Elisa Giannini Roberta Lattanzi Lucia Negri Pietro Melchiorri Luigi Ciocca Raniero Rocchi 《International journal of peptide research and therapeutics》2006,12(2):139-144
Syntheses are described of the nociceptin (1–13) amide [NC(1–13)-NH2] and of several analogues in which either one or both the phenylalanine residues (positions 1 and 4), the arginine residues (positions 8 and 12) and the alanine residues (positions 7 and 11) have been replaced by N-benzyl-glycine, N-(3-guanidino-propyl)-glycine and β-alanine, respectively. The preparation is also described of NC(1–13)-NH2 analogues in which either galactose or N-acetyl-galactosamine are β-O-glycosidically linked to Thr5 and/or to Ser10. Preliminary pharmacological experiments on mouse vas deferens preparations showed that Phe4, Thr5, Ala7 and Arg8 are crucial residues for OP4 receptor activation. Manipulation of Phe1 yielded peptides endowed with antagonist activity but [Nphe1] NC(1–13)-NH2 acted as an antagonist still possessing weak agonist activity. Introduction of the βAla residue either in position 7 or 11 of the [Nphe1] NC(1–13)-NH2 sequence, abolished any residual agonist activity and [Nphe1, βAla7] NC(1–13)-NH2 and [Nphe1, βAla11] NC(1–13)-NH2 acted as competitive antagonists only. Modification of both Ala7 and Ala11 abolished the antagonist activity of [Nphe1]NC(1–13)-NH2 probably by hindering receptor binding. Changes at positions 10 and 11 gave analogues still possessing agonist activity. [Ser(βGal)10] NC(1–13)-NH2 displayed an activity comparable with that of NC(1–13)-NH2, [Ser(βGalNAc)10] NC(1–13)-NH2 and [βAla11] NC(1–13)-NH2 were five and 10 times less active, respectively.The α-amino acid residues are of the l-configuration. Standard abbreviations for amino acid derivatives and peptides are according to the suggestions of the IUPAC-IUB Commission on Biochemical Nomeclature (1984), Eur. J. Biochem. 138, 9–37. Abbreviations listed in the guide published in (2003), J. Peptide Sci. 9, 1–8 are used without explanation. 相似文献
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Christina Martínez-Labarga O. Rickards R. Scacchi R.M. Corbo G. Biondi J.A. Pea C. Varas De Vieira A.E.B. Guevara M.S. Mesa Santurino G.F. De Stefano 《American journal of physical anthropology》1999,109(2):159-174
The genetic structure of two African-Ecuadorian communities, Rio Cayapas and Viche (Esmeraldas province, northwest Ecuador), was studied on the basis of ACP1, ADA, AK1, CA2, ESD, GLO1, G6PD, PGD, and PGM1 subtypes and thermostability, PGM2, HBβ, F13A, F13B, ORM1, AHSG, C6, C7, and APOC2 gene frequency, and migration data on 255 individuals. The fixation index of Wright (FST), correspondence, and genetic distance analysis were applied to compare the genetic relationships between these communities and other American populations of African ancestry. FST values from the migration data and surname origins suggest that Rio Cayapas is genetically more isolated and shows less mobility and admixture than does Viche. The genetic admixture estimates indicate a large contribution of African genes to the gene pool of both communities (74.3% to 58.4%), whereas the proportion of the Amerindian component differs significantly (14.5% in Rio Cayapas to 27.6% in Viche). Am J Phys Anthropol 109:159–174, 1999.© 1999 Wiley-Liss, Inc. 相似文献
416.
The influence of climate on the distribution of taxa has been extensively investigated in the last two decades through Habitat Suitability Models (HSMs). In this context, the Worldclim database represents an invaluable data source as it provides worldwide climate surfaces for both historical and future time horizons. Thousands of HSMs‐based papers have been published taking advantage of Worldclim 1.4, the first online version of this repository. In 2017, Worldclim 2.1 was released. Here, we evaluated spatially explicit prediction mismatch at continental scale, focusing on Europe, between HSMs fitted using climate surfaces from the two Worldclim versions (between‐version differences). To this aim, we simulated occurrence probability and presence‐absence across Europe of four virtual species (VS) with differing climate‐occurrence relationships. For each VS, we fitted HSMs upon uncorrelated bioclimatic variables derived from each Worldclim version at three grid resolutions. For each factor combination, HSMs attaining sufficient discrimination performance on spatially independent test data were projected across Europe under current conditions and various future scenarios, and importance scores of the single variables were computed. HSMs failed in accurately retrieving the simulated climate‐occurrence relationships for the climate‐tolerant VS and the one occurring under a narrow combination of climatic conditions. Under current climate, noticeable between‐version prediction mismatch emerged across most of Europe for these two VSs, whose simulated suitability mainly depended upon diurnal or yearly variability in temperature; differently, between‐version differences were more clustered toward areas showing extreme values, like mountainous massifs or southern regions, for VSs responding to average temperature and precipitation trends. Under future climate, the chosen emission scenarios and Global Climate Models did not evidently influence between‐version prediction discrepancies, while grid resolution synergistically interacted with VSs'' niche characteristics in determining extent of such differences. Our findings could help in re‐evaluating previous biodiversity‐related works relying on geographical predictions from Worldclim‐based HSMs. 相似文献
417.
Wanassa Beroual Karine Prvost David Lalaouna Nadia Ben Zaina Odile Valette Yann Denis Meriem Djendli Gaël Brasseur Matteo Brilli Marta Robledo Garrido Jose-Ignacio Jimenez-Zurdo Eric Mass Emanuele G. Biondi 《PLoS biology》2022,20(2)
Bacteria are powerful models for understanding how cells divide and accomplish global regulatory programs. In Caulobacter crescentus, a cascade of essential master regulators supervises the correct and sequential activation of DNA replication, cell division, and development of different cell types. Among them, the response regulator CtrA plays a crucial role coordinating all those functions. Here, for the first time, we describe the role of a novel factor named CcnA (cell cycle noncoding RNA A), a cell cycle–regulated noncoding RNA (ncRNA) located at the origin of replication, presumably activated by CtrA, and responsible for the accumulation of CtrA itself. In addition, CcnA may be also involved in the inhibition of translation of the S-phase regulator, GcrA, by interacting with its 5′ untranslated region (5′ UTR). Performing in vitro experiments and mutagenesis, we propose a mechanism of action of CcnA based on liberation (ctrA) or sequestration (gcrA) of their ribosome-binding site (RBS). Finally, its role may be conserved in other alphaproteobacterial species, such as Sinorhizobium meliloti, representing indeed a potentially conserved process modulating cell cycle in Caulobacterales and Rhizobiales.During cell cycle progression in the bacterium Caulobacter crescentus, the master cell cycle regulator CtrA is controlled by CcnA, a cell cycle-regulated non-coding RNA transcribed from a gene located at the origin of replication. 相似文献
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Responses of acutely isolated neurons from the rostral nucleus of the
solitary tract (rNST) to GABA receptor agonists and antagonists were
investigated using whole-cell recording in current clamp mode. The isolated
neurons retain their morphology and can be divided into multipolar,
elongate and ovoid cell types. Most rNST neurons (97%), including all three
cell types, respond to GABA with membrane hyperpolarization and a reduction
in input resistance. The GABA(A) receptor agonist muscimol reduces neuronal
input resistance in a concentration-dependent manner, whereas the GABA(B)
receptor agonist baclofen had no effect on any of the neurons tested. The
GABA and muscimol reversal potentials were both found to be -75 mV Both the
GABA competitive antagonist picrotoxin and the GABA(A) receptor antagonist
bicuculline block the effect of GABA in a concentration-dependent manner.
These results suggest that GABA activates all neurons in the rNST and that
inhibitory synaptic activity is important in brainstem processing of
gustatory and somatosensory information.
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