Water relations and growth of loblolly pine seedlings planted under a shelterwood and in a clear-cut     

Dalton CT  Messina MG 《Tree physiology》1995,15(1):19-26

We investigated the influence of shelterwood conditions on water relations and growth of loblolly pine (Pinus taeda L.) seedlings on two harsh sites in eastern Texas. Site I was harvested to provide four overstory density treatments (0, 2.3, 4.6 and 9.2 m(2) of residual basal area per ha). To quantify the effects of overstory competition, trenched and nontrenched subplots, each containing 25 one-year-old seedlings, were established within each overstory treatment plot, and predawn and midday water potentials (Psi(w)), seedling growth and survival were measured during the growing season. Leaf area and seedling biomass partitioning were measured at the end of the growing season. Site II was harvested to provide two overstory density treatments (0 and 6.9 m(2) ha(-1)) and planted with one-year-old loblolly pine seedlings. Seedling Psi(w), stomatal conductance (g(wv)), transpiration flux density (E), leaf area, height and survival were determined. On Site I, seedling Psi(w) increased with increasing overstory basal area, whereas trenching only substantially affected Psi(w) of seedlings in the 9.2 m(2) ha(-1) overstory treatment. Growth was not affected by overstory treatment or trenching. On Site II, Psi(w) and g(wv) were highest during the morning hours and lowest in the afternoon, whereas E peaked in the afternoon. Vapor pressure deficits and photosynthetic photon flux density were major factors in determining g(wv) differences between treatments. On individual days, the presence of an overstory increased Psi(w) and reduced both g(wv) and E. On Site II, leaf area was affected by overstory treatment throughout most of the study. We conclude that the presence of an overstory can have ameliorative effects on harsh sites at the western fringe of the loblolly pine natural range.  相似文献   

Microvascular characteristics of the human interdental papilla   总被引：1，自引：0，他引：1  

Scardina GA  Fucà G  Messina P 《Anatomia, histologia, embryologia》2007,36(4):266-268

The aim of this study was to observe the microcirculation characteristics of the human interdental papilla in healthy patients in vivo. Twenty healthy patients were examined. Capillaroscopy was used to investigate the characteristics of microcirculation of the human periodontal mucosa. Visibility, course, tortuosity, as well as the average caliber of the capillary loops and the number of visible capillary loops per square millimeter were evaluated for each patient. The investigation of gingival mucosa revealed capillary loops with a course both parallel and perpendicular to the surface. Our study has pointed out that capillaroscopy is a reliable method to study periodontal microcirculation in vivo. This method could be applied to the study of microcirculation in periodontal diseases. Future studies might evaluate whether microcirculation in that area is compromised or not during systemic pathologies involving peripheral microcirculation alterations.  相似文献   

Corpus Luteum–Endometrium–Embryo Interactions in the Dairy Cow: Underlying Mechanisms and Clinical Relevance     

RS Robinson  AJ Hammond  DC Wathes  MG Hunter  GE Mann 《Reproduction in domestic animals》2008,43(S2):104-112

Conception rates of dairy cows are currently declining at an estimated 1% every year. Approximately, 35% of embryos fail to prevent luteolysis during the first three weeks of gestation. Interactions between the corpus luteum, endometrium and embryo are critical to the successful establishment of pregnancy and inadequacies will result in the mortality of the embryo. For example, as little as a one day delay in the post-ovulatory rise of progesterone has serious consequences for embryo development and survival. Recently, we found that LH support, degree of vascularization and luteal cell steroidogenic capacity were not the major factors responsible for this luteal inadequacy, but are nevertheless essential for luteal development and function. Progesterone acting on its receptor in the endometrium stimulates the production of endometrial secretions on which the free-living embryo is dependent. However, their exact composition and effects of inadequate progesterone remains to be determined. The embryo is recognized through its secretion of interferon tau (IFNT), which suppresses luteolytic pulses of prostaglandin F_2α. In the cow, it is most likely that IFNT inhibits oxytocin receptor up-regulation directly and does not require the prior inhibition of oestrogen receptor α (ESR1). Unravelling the precise luteal-endometrium and embryo interactions is essential for us to understand pregnancy establishment and development of strategies to reverse the declining fertility of dairy cows.  相似文献   

Resveratrol–cyclodextrin complex affects the expression of genes associated with lipid metabolism in bovine in vitro produced embryos          下载免费PDF全文

V Torres  M Hamdi  MG Millán de la Blanca  R Urrego  J Echeverri  A López‐Herrera  D Rizos  A Gutiérrez‐Adán  MJ Sánchez‐Calabuig 《Reproduction in domestic animals》2018,53(4):850-858

Antioxidants have been widely used during in vitro production to decrease the negative effect of reactive oxygen species. It was reported that the complex resveratrol–methyl β‐cyclodextrin (RV ‐CD ) improves resveratrol's stability and bioavailability and increases its antioxidant activity. This study evaluates the effect of RV ‐CD during in vitro oocyte maturation (IVM ) or in vitro embryo culture (IVC ) on developmental competence and quantitative changes in gene expression of developmental important genes. In experiment 1, RV ‐CD was added to IVM media and maturation level, embryo development and oocytes, cumulus cells, and blastocysts gene expression by RT ‐qPCR were examined. In experiment 2, presumptive zygotes were cultured in SOF supplemented with RV ‐CD and embryo development and blastocysts gene expression by RT ‐qPCR were studied. A group without RV ‐CD (control^?) and a group with cyclodextrin (control⁺) were included. No differences were found in cleavage rate or blastocyst yield between groups. However, the expression of LIPE was higher in blastocysts derived from oocytes treated with resveratrol compared with control groups (p  <  .05). Blastocysts produced by IVC with resveratrol showed that RV ‐CD could modify the expression of genes related to lipid metabolism (CYP 51A1 , PNPLA 2 and MTORC 1 ) compared with control groups (p  < .05). RV ‐CD in the IVM and IVC media could reduce accumulated fat by increasing lipolysis and suppressing lipogenesis of blastocysts.  相似文献   

Phenotypic and genotypic profiling of antimicrobial resistance in enteric Escherichia coli communities isolated from finisher pigs in Australia          下载免费PDF全文

MG Smith  D Jordan  JS Gibson  RN Cobbold  TA Chapman  S Abraham  DJ Trott 《Australian veterinary journal》2016,94(10):371-376

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Aromatic‐ring‐functionalised benzoxazinones in the system Oryza sativa–Echinochloa crus‐galli as biorational herbicide models     

Francisco A Macías  Nuria Chinchilla  Rosa M Varela  José MG Molinillo  David Marín  Joao M de Siqueira 《Pest management science》2009,65(10):1104-1113

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Localized reconnection in the near jovian magnetotail     

CT Russell  KK Khurana  DE Huddleston  MG Kivelson 《Science (New York, N.Y.)》1998,280(5366):1061-1064

The oppositely directed magnetic field in the jovian magnetic tail is expected eventually to reconnect across the current sheet, allowing plasma produced deep inside the magnetosphere near Io's orbit to escape in the antisolar direction down the tail. The Galileo spacecraft found localized regions of strong northward and southward field components beyond about 50 jovian radii in the postmidnight, predawn sector of the jovian magnetosphere. These pockets of vertical magnetic fields can be stronger than the surrounding magnetotail and magnetodisk fields. They may result from episodic reconnection of patches of the near jovian magnetotail.  相似文献   

From the editors     

Jose Alvarez  William A. Messina 《Agriculture and Human Values》1993,10(3):1-2

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A Magnetic Signature at Io: Initial Report from the Galileo Magnetometer   总被引：1，自引：0，他引：1  

MG Kivelson  KK Khurana  RJ Walker  CT Russell  JA Linker  DJ Southwood  C Polanskey 《Science (New York, N.Y.)》1996,273(5273):337-340

During the inbound pass of the Galileo spacecraft, the magnetometer acquired 1 minute averaged measurements of the magnetic field along the trajectory as the spacecraft flew by Io. A field decrease, of nearly 40 percent of the background jovian field at closest approach to Io, was recorded. Plasma sources alone appear incapable of generating perturbations as large as those observed and an induced source for the observed moment implies an amount of free iron in the mantle much greater than expected. On the other hand, an intrinsic magnetic field of amplitude consistent with dynamo action at Io would explain the observations. It seems plausible that Io, like Earth and Mercury, is a magnetized solid planet.  相似文献   

Ordered mesoporous materials from metal nanoparticle-block copolymer self-assembly     

Warren SC  Messina LC  Slaughter LS  Kamperman M  Zhou Q  Gruner SM  DiSalvo FJ  Wiesner U 《Science (New York, N.Y.)》2008,320(5884):1748-1752

The synthesis of ordered mesoporous metal composites and ordered mesoporous metals is a challenge because metals have high surface energies that favor low surface areas. We present results from the self-assembly of block copolymers with ligand-stabilized platinum nanoparticles, leading to lamellar CCM-Pt-4 and inverse hexagonal (CCM-Pt-6) hybrid mesostructures with high nanoparticle loadings. Pyrolysis of the CCM-Pt-6 hybrid produces an ordered mesoporous platinum-carbon nanocomposite with open and large pores (>/=10 nanometers). Removal of the carbon leads to ordered porous platinum mesostructures. The platinum-carbon nanocomposite has very high electrical conductivity (400 siemens per centimeter) for an ordered mesoporous material fabricated from block copolymer self-assembly.  相似文献