Robust design and the use of auxiliary variables in estimating population size for an open population

We consider the problem of estimating the population size for an open population where the data are collected over secondary periods within primary periods according to a robust design suggested by Pollock (1982, Journal of Wildlife Management 46, 757-760). A conditional likelihood is used to estimate the parameters associated with a generalized linear model in which the capture probability is assumed to have a logistic form depending on individual covariates. A Horvitz-Thompson-type estimator is used to estimate the population size for each primary period and the survival probabilities between primary periods. The asymptotic properties of the proposed estimators are investigated through simulation and are found to perform well. A data set for such a robust design of a small-mammal capture-recapture study conducted at Dummy Bottom within Browns Park National Wildlife Refuge is analyzed.     

水分胁迫下盆栽冬小麦根系生长与苗系生长及某些生理特性的关系

水分胁迫下,盆栽冬小麦根干重和根长密度呈直线正相关。鉴于根长密度反映了土壤中根系最活跃的部分［５］,是研究植物根系吸收水分和养分的最优参数之一［６］,本文用之研究了它与地上部生物量、净同化速率、叶水势和叶片相对含水量、气孔阻力和蒸腾速率的关系。结果表明,根长密度与净同化速率和地上部干重呈直线负相关,与叶水势和叶片相对含水量呈直线正相关;与气孔阻力呈直线负相关,与蒸腾速率呈直线正相关。为实验室进行冬小麦生长控制与生理特性控制提供了一定的基础。     

扁秆藨草种群内禀增长率的研究

采用“定期起苗”法,从６ 月１０ 日—８ 月３０ 日止,分别统计从越冬块茎上萌发出的再生苗及其后代蔓生枝系再生苗的数量,从而得出扁秆藨草再生苗各旬株数增长的指数方程;又用“定株观察”法,对１２ 株越冬块茎上的再生苗及其全部后代植株开花、结实数量进行统计,探讨扁秆藨草有性繁殖的能力,然后进行综合计算,求得扁秆藨草种群的内禀增长率ｒ＝７．２４,阐明了扁秆藨草很高的内禀增长率是其种群过度生长的根本原因;通过对其过度生长关键时刻的判断,选择灭草的关键期,有效地灭杀此种恶性杂草     

A 22kDa protein specific for yeast mitochondrial nucleoids is an unidentified putative ribosomal protein encoded in open reading frame YGL068W

Summary. Mitochondrial-nucleoid (mt-nucleoid) proteins of the yeast Saccharomyces cerevisiae were separated by two-dimensional gel electrophoresis. Analysis of the N-terminal amino acid sequence showed that a 22kDa protein which is unique in the mt-nucleoid fraction is an unidentified protein encoded in the open reading frame YGL068W and shows a homology with the ribosomal protein L7/L12 of bacteria. We named this protein Mnp1p (for the mitochondrial-nucleoid protein 1). Immunoblotting of each fraction with an anti-Mnp1p antibody during the mt-nucleoid isolation showed that Mnp1p is highly concentrated in the mt-nucleoid fraction. Immunofluorescence microscopy suggested that Mnp1p is localized to mitochondria in vivo, and a significant amount of Mnp1p is associated with the mt-nucleoids. On the other hand, Northern blotting showed that a large amount of large and small mitochondrial ribosomal RNAs was not associated with the mt-nucleoids and remained in the supernatant after the isolation of mt-nucleoids. The null mutation of MNP1 led to a respiratory-deficient phenotype, but the morphology of the mt-nucleoids in the transformants carrying the null mutation was normal. These results suggest that a significant amount of Mnp1p plays a role as a major component of the mt-nucleoids.Correspondence and reprints: Department of Physics, Informatics, and Biology, Faculty of Science, Yamaguchi University, Yamaguchi 753-8512, Japan.     

Effects of Na+ on the Predominant K+ Channel in the Tonoplast of Chara: Decrease of Conductance by Blocks in 100 Nanosecond Range and Induction of Oligo- or Poly-subconductance Gating Modes

We present three mechanisms by which Na⁺ inhibits the open channel currents of the predominant K⁺ channel in the tonoplast of Chara corallina: (i) Fast block, i.e., short (100 ns range) interruptions of the open channel current which are determined by open channel noise analysis, (ii): Oligo-subconductance mode, i.e., a gating mode which occurs preferentially in the presence of Na⁺; this mode comprises a discrete number (here 3) of open states with smaller conductances than normal, and (iii): Polysubconductance mode, i.e., a gating mode with a nondiscrete, large number (>30) of states with smaller conductances than the main open channel conductance. This novel mode has also been observed only in the presence of Na⁺. Received: 16 November 1999/Revised: 8 February 2000     

Extra- and Intracellular Proton-Binding Sites of Volume-Regulated Anion Channels

We have investigated the effects of extracellular and intracellular pH on single channel and macroscopic (macropatches) currents through volume-regulated anion channels (VRAC) in endothelial cells. Protonation of extracellular binding sites with an apparent pK of 4.6 increased voltage independent of the single-channel amplitude. Cytosolic acidification had a dual effect on VRAC currents: on the one hand, it increased single channel conductance by ∼20% due to protonation of a group with an apparent pK of 6.5 and a Hill coefficient of 2. On the other hand, it reduced channel activity due to protonation of a group with an apparent pK of 6.3 and a Hill coefficient of 2.1. This dual effect enhances the macroscopic current at a slightly acidic pH but inhibits it at more acidic pH. Cytosolic alkalization also reduced channel activity with a pK of 8.4 and a Hill coefficient of 1.9, but apparently did not affect single-channel conductance. These data show that VRAC channels are maintained in an active state in a narrow pH range around the normal physiological pH and shut down outside this range. They also show that HEPES-buffered pipette solutions do not effectively buffer pH in the vicinity of the VRAC channels. Received: 31 January 2000/Revised: 21 April 2000     

Intracellular Mg<Superscript><Emphasis Type="Bold">2+</Emphasis></Superscript> Influences Both Open and Closed Times of a Native Ca<Superscript><Emphasis Type="Bold">2+</Emphasis></Superscript>-activated BK Channel in Cultured Human Renal Proximal Tubule Cells

Effects of intracellular Mg²⁺ on a native Ca²⁺-and voltage-sensitive large-conductance K⁺ channel in cultured human renal proximal tubule cells were examined with the patch-clamp technique in the inside-out mode. At an intracellular concentration of Ca²⁺ ([Ca²⁺]_i) of 10⁻⁵–10⁻⁴ M, addition of 1–10 mM Mg²⁺ increased the open probability (P_o) of the channel, which shifted the P_o –membrane potential (V_m) relationship to the negative voltage direction without causing an appreciable change in the gating charge (Boltzmann constant). However, the Mg²⁺-induced increase in P_o was suppressed at a relatively low [Ca²⁺]_i (10^−5.5–10⁻⁶ M). Dwell-time histograms have revealed that addition of Mg²⁺ mainly increased P_o by extending open times at 10⁻⁵ M Ca²⁺ and extending both open and closed times simultaneously at 10^−5.5 M Ca²⁺. Since our data showed that raising the [Ca²⁺]_i from 10⁻⁵ to 10⁻⁴ M increased P_o mainly by shortening the closed time, extension of the closed time at 10^−5.5 M Ca²⁺ would result from the Mg²⁺-inhibited Ca²⁺-dependent activation. At a constant V_m, adding Mg²⁺ enhanced the sigmoidicity of the P_o–[Ca²⁺]_i relationship with an increase in the Hill coefficient. These results suggest that the major action of Mg²⁺ on this channel is to elevate P_o by lengthening the open time, while extension of the closed time at a relatively low [Ca²⁺]_i results from a lowering of the sensitivity to Ca²⁺ of the channel by Mg²⁺, which causes the increase in the Hill coefficient. M. Kubokawa and Y. Sohma contributed equally to this work.     

Binding patterns of vanadium ions with different valence states to human serum transferrin studied by HPLC/high-resolution ICP-MS

Vanadium (V) is an essential metal for mammals and has different valence states. In blood, V is bound to serum transferrin (Tf), a glycoprotein which has two metal-binding sites, and carbonate is generally required for the binding. In this study, the binding patterns of V(III), V(IV), and V(V) to human serum Tf (hTf) were analyzed using an HPLC system equipped with an anion-exchange column and directly connected to a high-resolution inductively coupled plasma-mass spectrometer for metal detection (51V). In affinity to hTf, the three ions were ranked V(III)>V(IV)>V(V) in the presence of bicarbonate and V(III) reverse congruent V(IV)>V(V) in the absence. Intermediates in the "open forms" binding to the respective sites were detected at the initial stage. V(IV) and V(V) were bound to the N-lobe site in the "closed form" and "open form," respectively. In the absence of bicarbonate, V ions with respective valence states were bound to hTf in the "open form." In terms of binding to hTf, tri-valent V was most favorable in the presence of bicarbonate.     

腹腔镜与开腹胰十二指肠切除术治疗胰头癌的疗效对比及术后肿瘤早期复发的随访研究

摘要 目的：对比腹腔镜与开腹胰十二指肠切除术治疗胰头癌的疗效,并分析术后肿瘤早期复发的影响因素。方法：选择2019年3月~2020年4月期间四川大学华西空港医院普外科收治的15例及四川大学华西医院胰腺外科收治的65例共计80例胰头癌患者,根据手术方式的不同分为开腹组和微创组,例数分别为32例和48例,对比两组围术期相关临床指标、并发症发生率和随访期间的肿瘤早期复发率。采用多因素Logistic回归分析术后早期复发的影响因素。结果：微创组的手术时间长于开腹组,住院费用多于开腹组,术中出血量少于开腹组,下床活动时间、术后排气时间、开始进食时间、术后住院时间短于开腹组（P<0.05）。两组并发症发生率对比无差异（P>0.05）。两组术后肿瘤早期复发率对比差异无统计学意义（P>0.05）。单因素分析结果显示,胰头癌患者术后肿瘤早期复发与年龄、肿瘤最大直径、有无淋巴结转移、有无脉管癌栓、有无神经侵犯、术前白蛋白、术前糖类抗原125（CA125）、术前癌胚抗原（CEA）水平、术后有无放化疗有关（P<0.05）。多因素Logistic回归分析显示：淋巴结转移、脉管癌栓、神经侵犯、术后未放化疗以及术前CA125水平较高是胰头癌患者术后肿瘤早期复发的危险因素（P<0.05）。结论：相较于传统开腹手术,腹腔镜下行胰十二指肠切除术治疗胰头癌,可缩短住院时间,促进患者术后恢复,但两者间并发症发生率和术后早期复发率无显著差异。胰头癌术后肿瘤早期复发受到淋巴结转移、脉管癌栓、神经侵犯、术后放化疗、术前CA125水平等多种因素的影响。     

Homebase behavior of zebrafish in novelty-based paradigms

Zebrafish (Danio rerio) are emerging as a promising model species in neuroscience research. Many traditional rodent behavioral paradigms may be adapted for zebrafish testing. Exposing zebrafish to three different “open field” tanks for 30 min, we showed that fish display robust homebase behavior, in which one area of the tank is chosen as a preferred point of reference during the test, which the fish frequently return to and spend a longer duration in. This phenotype strikingly resembles rodent homebase behavior, confirming that both species use homebases as “reference points” for their exploration. Our study introduces a simple method for zebrafish homebase phenotyping, and further supports the utility of these fish in neurobehavioral and cognitive research.