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221.
Current environmental conditions are known to affect plant growth, morphology, phenology, and therefore, plant performance.
However, effects of the previous-year environmental conditions can also affect plant structure by altering bud growth, and
proportion and date of budburst. Here, we analysed the effects of previous-year water stress and shade on bud size, percentage,
and date of budburst in seedlings of three co-occurring Iberian Quercus species in two independent experiments. Responses of apical, lateral, and basal buds were checked during an annual cycle.
In the first experiment, seedlings of two evergreens (Q. coccifera L., Q. ilex subsp. ballota (Desf.) Samp.) and a deciduous-marcescent tree (Q. faginea Lam.) were grown under two levels of summer watering. In the second experiment, seedlings were grown under three light intensities.
Soluble sugars and starch in shoots and roots were measured before budburst. Summer drought increased bud size of all species
and advanced budburst of Q. ilex and Q. coccifera. Moderate and/or intense shade tended to reduce bud size and delay budburst in all species. These responses seem related
to changes in the date of bud formation rather than to the amount of carbon reserves, which were reduced both by drought and
shade. Treatments affected percentage of budburst in lateral buds, which was reduced by shade and water stress, probably leading
to narrower crowns. These results show that previous-year environmental conditions are relevant for plant phenology and structure.
The different responses in budburst date between the deciduous and the evergreens might alter their competition relationships
at seedling stage. 相似文献
222.
Augusto B. Reis Fabiano C. Araújo Virginia M. Pereira Adelina M. Dos Reis Robson A. Santos Fernando M. Reis 《Journal of molecular histology》2010,41(1):75-80
The presence of classical components of the renin-angiotensin system has been demonstrated in the male reproductive tract,
mainly in the testes and epididymis. The objective of this study was to verify the localization of angiotensin (Ang)-(1–7)
and its receptor Mas in human testis. The study included 12 men with previously proven fertility submitted to orchiectomy
for prostate cancer and 20 infertile men submitted to testicular biopsy for infertility work-up, comprising a subgroup with
obstructive azoospermia/normal spermatogenesis (n = 8) and another with non-obstructive azoospermia and severely impaired spermatogenesis (n = 12). Testicular tissue samples were processed by immunohistochemistry and real time polymerase chain reaction. Ang-(1–7)
was strongly expressed in the interstitial compartment, mainly in Leydig cells, with similar intensity in all groups evaluated.
The peptide was also detected in the seminiferous tubules, but with much less intensity compared to interstitial cells. The
receptor Mas was equally distributed between interstitial and tubular compartments and was found in all layers of the normal
seminiferous epithelium. However, neither Ang-(1–7) nor Mas were detected in the seminiferous tubules of samples with impaired
spermatogenesis. The testicular samples of infertile men with impaired spermatogenesis (non-obstructive azoospermia) expressed
Mas and ACE2 mRNA at lower concentrations (fold change = 0.06 and 0.04, respectively, P < 0.05) than samples with full spermatogenesis (obstructive azoospermia). This shows, for the first time, the immunolocalization
of Ang-(1–7) and its receptor Mas in testes of fertile and infertile men, and suggests that this system may be altered when
spermatogenesis is severely impaired. 相似文献
223.
Elizabeth A. Archie Tammy Henry Jesus E. Maldonado Cynthia J. Moss Joyce H. Poole Virginia R. Pearson Suzan Murray Susan C. Alberts Robert C. Fleischer 《Immunogenetics》2010,62(2):85-100
Genes of the vertebrate major histocompatibility complex (MHC) are crucial to defense against infectious disease, provide
an important measure of functional genetic diversity, and have been implicated in mate choice and kin recognition. As a result,
MHC loci have been characterized for a number of vertebrate species, especially mammals; however, elephants are a notable
exception. Our study is the first to characterize patterns of genetic diversity and natural selection in the elephant MHC.
We did so using DNA sequences from a single, expressed DQA locus in elephants. We characterized six alleles in 30 African
elephants (Loxodonta africana) and four alleles in three Asian elephants (Elephas maximus). In addition, for two of the African alleles and three of the Asian alleles, we characterized complete coding sequences
(exons 1–5) and nearly complete non-coding sequences (introns 2–4) for the class II DQA loci. Compared to DQA in other wild
mammals, we found moderate polymorphism and allelic diversity and similar patterns of selection; patterns of non-synonymous
and synonymous substitutions were consistent with balancing selection acting on the peptides involved in antigen binding in
the second exon. In addition, balancing selection has led to strong trans-species allelism that has maintained multiple allelic
lineages across both genera of extant elephants for at least 6 million years. We discuss our results in the context of MHC
diversity in other mammals and patterns of evolution in elephants. 相似文献
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225.
? Premise of the study: The use of continuous morphological characters in taxonomy is traditionally contingent on the existence of discrete diagnostic characters. When plant species are the result of recent divergence and gene flow and/or hybridization occur, the use of continuous morphological characters may help in species identification and delimitation. Between nine and 15 species have been recognized in the last treatments of Hedera. The recent divergence of the species and the involvement of allopolyploidization as the main force in this process may have greatly impeded the establishment of clear limits and contributed to multiple taxonomic proposals. ? Methods: A multivariate statistical decision-making procedure was applied to 56 quantitative morphological characters and 602 specimens to identify and delimit Hedera species under the general lineage concept. Species' exclusive genetic ancestry was evaluated with the genealogical sorting index from the Bayesian inference trees of 30 Hedera ITS sequences. ? Key results: The decision-making procedure allowed recognizing 12 species and two groups (stellate and scale-like trichome groups) in Hedera and provided statistical support for making decisions about long-standing taxonomic controversies. Common ancestry was detected for the populations of three species even in the absence of the species monophyly. ? Conclusions: Quantitative variation supports discrete variation and provides statistical support for the taxa recognized in some recent proposals of Hedera. The need of explicit analysis of quantitative data are claimed to reduce taxonomic subjectivity and ease decision-making when qualitative data fail. 相似文献
226.
Tompson SW Bacino CA Safina NP Bober MB Proud VK Funari T Wangler MF Nevarez L Ala-Kokko L Wilcox WR Eyre DR Krakow D Cohn DH 《American journal of human genetics》2010,87(5):708-712
Fibrochondrogenesis is a severe, autosomal-recessive, short-limbed skeletal dysplasia. In a single case of fibrochondrogenesis, whole-genome SNP genotyping identified unknown ancestral consanguinity by detecting three autozygous regions. Because of the predominantly skeletal nature of the phenotype, the 389 genes localized to the autozygous intervals were prioritized for mutation analysis by correlation of their expression with known cartilage-selective genes via the UCLA Gene Expression Tool, UGET. The gene encoding the α1 chain of type XI collagen (COL11A1) was the only cartilage-selective gene among the three candidate intervals. Sequence analysis of COL11A1 in two genetically independent fibrochondrogenesis cases demonstrated that each was a compound heterozygote for a loss-of-function mutation on one allele and a mutation predicting substitution for a conserved triple-helical glycine residue on the other. The parents who were carriers of missense mutations had myopia. Early-onset hearing loss was noted in both parents who carried a loss-of-function allele, suggesting COL11A1 as a locus for mild, dominantly inherited hearing loss. These findings identify COL11A1 as a locus for fibrochondrogenesis and indicate that there might be phenotypic manifestations among carriers. 相似文献
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230.
Biswas PS Pedicord V Ploss A Menet E Leiner I Pamer EG 《Journal of immunology (Baltimore, Md. : 1950)》2007,179(7):4520-4528
Regulation of CD8 T cell expansion and contraction is essential for successful immune defense against intracellular pathogens. IL-10 is a regulatory cytokine that can restrict T cell responses by inhibiting APC functions. IL-10, however, can also have direct effects on T cells. Although blockade or genetic deletion of IL-10 enhances T cell-mediated resistance to infections, the extent to which IL-10 limits in vivo APC function or T cell activation/proliferation remains unknown. Herein, we demonstrate that primary and memory CD8 T cell responses following Listeria monocytogenes infection are enhanced by the absence of IL-10. Surface expression of the IL-10R is transiently up-regulated on CD8 T cells following activation, suggesting that activated T cells can respond to IL-10 directly. Consistent with this notion, CD8 T cells lacking IL-10R2 underwent greater expansion than wild-type T cells upon L. monocytogenes infection. The absence of IL-10R2 on APCs, in contrast, did not enhance T cell responses following infection. Our studies demonstrate that IL-10 produced during bacterial infection directly limits expansion of pathogen-specific CD8 T cells and reveal an extrinsic regulatory mechanism that modulates the magnitude of memory T cell responses. 相似文献