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941.
Agustin Sanguinetti Cristiano Roberto Buzatto Marcelo Pedron Kevin L. Davies Pedro Maria de Abreu Ferreira Sara Maldonado Rodrigo B. Singer 《Annals of botany》2012,110(8):1607-1621
Background and Aims
The pollination biology of very few Chloraeinae orchids has been studied to date, and most of these studies have focused on breeding systems and fruiting success. Chloraea membranacea Lindl. is one of the few non-Andean species in this group, and the aim of the present contribution is to elucidate the pollination biology, functional floral morphology and breeding system in native populations of this species from Argentina (Buenos Aires) and Brazil (Rio Grande do Sul State).Methods
Floral features were examined using light microscopy, and scanning and transmission electron microscopy. The breeding system was studied by means of controlled pollinations applied to plants, either bagged in the field or cultivated in a glasshouse. Pollination observations were made on natural populations, and pollinator behaviour was recorded by means of photography and video.Key Results
Both Argentinean and Brazilian plants were very consistent regarding all studied features. Flowers are nectarless but scented and anatomical analysis indicates that the dark, clavate projections on the adaxial labellar surface are osmophores (scent-producing glands). The plants are self-compatible but pollinator-dependent. The fruit-set obtained through cross-pollination and manual self-pollination was almost identical. The main pollinators are male and female Halictidae bees that withdraw the pollinarium when leaving the flower. Remarkably, the bees tend to visit more than one flower per inflorescence, thus promoting self-pollination (geitonogamy). Fruiting success in Brazilian plants reached 60·78 % in 2010 and 46 % in 2011. Some pollinarium-laden female bees were observed transferring pollen from the carried pollinarium to their hind legs. The use of pollen by pollinators is a rare record for Orchidaceae in general.Conclusions
Chloraea membrancea is pollinated by deceit. Together, self-compatibility, pollinarium texture, pollinator abundance and behaviour may account for the observed high fruiting success. It is suggested that a reappraisal and re-analysis of important flower features in Chloraeinae orchids is necessary. 相似文献942.
Noé Manuel Montaño Alejandro Alarcón Sara Lucía Camargo-Ricalde Laura Verónica Hernández-Cuevas Javier Álvarez-Sánchez Ma. del Carmen A. González-Chávez Mayra E. Gavito Irene Sánchez-Gallen José Ramos-Zapata Patricia Guadarrama Ignacio E. Maldonado-Mendoza Silvia Castillo-Argüero Rosalva García-Sánchez Dora Trejo Ronald Ferrera-Cerrato 《Symbiosis (Philadelphia, Pa.)》2012,57(3):111-126
This review analyzes the historical development and advances of the research on arbuscular mycorrhizal fungi (AMF) in Mexico, as well as the prospects for future research. AMF-research has been focused on studying both diversity and functionality in several ecosystems of Mexico, but mainly in the tropical dry and rainy ecosystems, and the agricultural systems. In Mexico, 95 species of AMF have been recorded, representing 41% of the known species worldwide. The functional effects of AMF colonization have been examined in approximately 10% of the known host plants, but greenhouse studies continue to dominate over those conducted under field conditions. Even though research to date has been at the organismic level, further effort is needed due to the high plant diversity in Mexico. Studies on AMF biomass under field conditions and more taxonomic determination are required based on morphological features, biochemical determinations (fatty acids) and molecular tools. In addition, ecophysiological and ecological in situ studies would help in understanding the relationships among AMF, soil fauna, nutrients, and host plants. The contribution of AMF to ecosystemic processes is a priority line of research that requires an integrated approach (inter- and multidisciplinary) in order to define the role of AM symbioses for biogeochemical models. The creation of a Mexican mycorrhizal research network has and will help to identify the main challenges. Generating similar research protocols, and sharing databases and experience will assist mycorrhizologists working under the diverse financial and ecological contexts that is to be found in Mexico and Latin America. 相似文献
943.
Al-Sukhni W Joe S Lionel AC Zwingerman N Zogopoulos G Marshall CR Borgida A Holter S Gropper A Moore S Bondy M Klein AP Petersen GM Rabe KG Schwartz AG Syngal S Scherer SW Gallinger S 《Human genetics》2012,131(9):1481-1494
Adenocarcinoma of the pancreas is a significant cause of cancer mortality, and up to 10?% of cases appear to be familial. Heritable genomic copy number variants (CNVs) can modulate gene expression and predispose to disease. Here, we identify candidate predisposition genes for familial pancreatic cancer (FPC) by analyzing germline losses or gains present in one or more high-risk patients and absent in a large control group. A total of 120 FPC cases and 1,194 controls were genotyped on the Affymetrix 500K array, and 36 cases and 2,357 controls were genotyped on the Affymetrix 6.0 array. Detection of CNVs was performed by multiple computational algorithms and partially validated by quantitative PCR. We found no significant difference in the germline CNV profiles of cases and controls. A total of 93 non-redundant FPC-specific CNVs (53 losses and 40 gains) were identified in 50 cases, each CNV present in a single individual. FPC-specific CNVs overlapped the coding region of 88 RefSeq genes. Several of these genes have been reported to be differentially expressed and/or affected by copy number alterations in pancreatic adenocarcinoma. Further investigation in high-risk subjects may elucidate the role of one or more of these genes in genetic predisposition to pancreatic cancer. 相似文献
944.
The aim of this research was to determine the potential probiotic activity of Lactobacillus
acidophilus ATCC 4356 against several human Campylobacter jejuni isolates. The ability to inhibit the pathogen’s growth was evaluated by co-culture experiments as well as by antimicrobial
assays with cell-free culture supernatant (CFCS), while interference with adhesion/invasion to intestinal Caco-2 cells was
studied by exclusion, competition, and displacement tests. In the co-culture experiments L. acidophilus ATCC 4356 strain reduced the growth of C. jejuni with variable percentages of inhibition related to the contact time. The CFCS showed inhibitory activity against C. jejuni strains, stability to low pH, and thermal treatment and sensitivity to proteinase K and trypsin. L. acidophilus ATCC 4356 was able to reduce the adhesion and invasion to Caco-2 cells by most of the human C. jejuni strains. Displacement and exclusion mechanisms seem to be the preferred modalities, which caused a significant reduction
of adhesion/invasion of pathogens to intestinal cells. The observed inhibitory properties of L. acidophilus ATCC 4356 on growth ability and on cells adhesion/invasion of C. jejuni may offer potential use of this strain for the management of Campylobacter infections. 相似文献
945.
The aims of the present study were to determine whether the estimations of the frontal area of the combined cyclist-bicycle (APCB) obtained with the Heil's non-logarithmic prediction equations (NPE) in the stem position (SP), brake hoods position (BHP) and drops position (DP) are comparable to the measured APCB with the computerized planimetry (CP) method, and to analyse with the CP method and the NPE the influence of the body position on the APCB. Nineteen participants competing in the Spanish Road Cycling First division took part in the study. The NPE overestimated the APCB in the BHP and in the DP compared with the measured APCB with the CP method (6.9% and 5.1%, respectively; p<0.05). Significant differences among the three positions were obtained with the CP method. The overestimation of the APCB with the NPE in the BHP and in the DP and the less sensitivity of the NPE to show significant differences between the SP and DP suggest that the NPE are not appropriate to accurately predict the APCB. 相似文献
946.
Molinas SM Trumper L Marinelli RA 《American journal of physiology. Renal physiology》2012,303(3):F458-F466
Mitochondrial ammonia synthesis in proximal tubules and its urinary excretion are key components of the renal response to maintain acid-base balance during metabolic acidosis. Since aquaporin-8 (AQP8) facilitates transport of ammonia and is localized in inner mitochondrial membrane (IMM) of renal proximal cells, we hypothesized that AQP8-facilitated mitochondrial ammonia transport in these cells plays a role in the response to acidosis. We evaluated whether mitochondrial AQP8 (mtAQP8) knockdown by RNA interference is able to impair ammonia excretion in the human renal proximal tubule cell line, HK-2. By RT-PCR and immunoblotting, we found that AQP8 is expressed in these cells and is localized in IMM. HK-2 cells were transfected with short-interfering RNA targeting human AQP8. After 48 h, the levels of mtAQP8 protein decreased by 53% (P < 0.05). mtAQP8 knockdown decreased the rate of ammonia released into culture medium in cells grown at pH 7.4 (-31%, P < 0.05) as well as in cells exposed to acid (-90%, P < 0.05). We also evaluated mtAQP8 protein expression in HK-2 cells exposed to acidic medium. After 48 h, upregulation of mtAQP8 (+74%, P < 0.05) was observed, together with higher ammonia excretion rate (+73%, P < 0.05). In vivo studies in NH(4)Cl-loaded rats showed that mtAQP8 protein expression was also upregulated after 7 days of acidosis in renal cortex (+51%, P < 0.05). These data suggest that mtAQP8 plays an important role in the adaptive response of proximal tubule to acidosis possibly facilitating mitochondrial ammonia transport. 相似文献
947.
Bustamante-Aragonés A Rodríguez de Alba M Perlado S Trujillo-Tiebas MJ Arranz JP Díaz-Recasens J Troyano-Luque J Ramos C 《Gene》2012,504(1):144-149
Prenatal diagnosis (PD) is available for pregnancies at risk of monogenic disorders. However, PD requires the use of invasive obstetric techniques for fetal-sample collection and therefore, involves a risk of fetal loss. Circulating fetal DNA in the maternal bloodstream is being used to perform non-invasive prenatal diagnosis (NIPD). NIPD is a challenging discipline because of the biological features of the maternal blood sample. Maternal blood is an unequal mixture of small (and fragmented) amounts of fetal DNA within a wide background of maternal DNA. For this reason, initial NIPD studies have been based on the analysis of specific paternally inherited fetal tracts not present in the maternal genome so as to ensure their fetal origin. Following this strategy, different NIPD studies have been carried out, such as fetal-sex assessment for pregnancies at risk of X-linked disorders, RhD determination, and analysis of single-gene disorders with a paternal origin. The study of the paternal mutation can be used for fetal diagnosis of dominant disorders or to more accurately assess the risk of an affected child in case of recessive diseases. Huntington's disease, cystic fibrosis, or achondroplasia are some examples of diseases studied using NIPD. New technologies are opening NIPD to the analysis of maternally inherited fetal tracts. NIPD of trisomy 21 is the latest study derived from the use of next-generation sequencing (NGS). 相似文献
948.
MicroRNA (miRNA) play important roles in the development and physiological function of hematopoietic stem/progenitor and mature cell lineages. In addition, deregulated miRNA expression and subsequent gene expression changes are associated with hematologic diseases including myelodysplastic syndromes and acute myeloid leukemia. This review focuses on myelopoiesis as a model to highlight the involvement of miRNA in the regulation of normal and malignant cellular signaling pathways. By incorporating miRNA regulation into well-established myeloid signal transduction pathways, we hope to shed light on targetable factors both upstream and downstream of miRNA signaling. These pathway-specific miRNA functions suggest scenarios wherein miRNA-based therapeutics may be beneficial either alone or in combination with current therapies. 相似文献
949.
The mistletoe, Viscum album, living on Scots pine (Pinus sylvestris) has been reported barely to regulate its transpiration and thus heavily to affect the gas exchange of its host. The extent of this mistletoe effect and its underlying mechanism has, so far, only been partially analysed. In this study, pine branches with different mistletoe infestation levels were investigated by sap flow gauges and analysed with a modelling approach to identify the mistletoe-induced stomatal regulation of pine and its consequences for the water and carbon balances of the tree. It was found that Viscum album barely regulates its stomata and that pines consequently compensate for the additional water loss of mistletoes by closing their own stomata. Despite the reduced stomatal aperture of the needles, the total water loss of branches with mistletoes increased. Furthermore, the increasingly closed stomata reduced carbon assimilation for the pine. Such a negative effect of the mistletoes on pine's stomatal conductance and carbon gain was particularly strong during dry periods. Our study therefore suggests that mistletoe-induced stomatal closure is a successful mechanism against dying from hydraulic failure in the short term but increases the risk of carbon starvation in the long term. With the current conditions in Valais, Switzerland, a tree with more than about 10-20% of its total leaf area attributable to mistletoes is at the threshold of keeping a positive carbon balance. The currently increasing mistletoe abundance, due to increasing mean annual temperatures, is therefore accelerating the ongoing pine decline in many dry inner-Alpine valleys. 相似文献
950.