LBL, a novel, developmentally regulated, laminin-binding lectin.

A 190/220-kDa complex found in integrin preparations was purified, and monoclonal antibodies were raised against it. The immunoaffinity-purified complex appears to be a trimer of very similar or identical 70-kDa subunits. It is a novel extracellular matrix molecule as determined by its subunit composition, N-terminal amino acid sequence, and in vivo localization. It is distributed widely in basement membranes including those from muscle, nerve, and kidney. It is also present in connective tissue regions such as perineurium and perimysium. It has the unusual property that it is initially expressed very late in avian development near the time of hatching. This protein is found to copurified with integrin because it binds to the carbohydrate support in Sepharose. Hemagglutination assays with mono- and disaccharides show that it functions as a lectin with galactoside-binding specificity. This protein is also found to bind strongly and specifically to laminin at a site distinct from its lectin activity, but does not bind to fibronectin or type IV collagen. The protein appears to be conserved and is a common contaminant of many laminin preparations. We call this novel protein "LBL" for laminin-binding lectin.     

Structural diversity in the extracellular faces of peptidergic G-protein-coupled receptors. Molecular cloning of the mouse C5a anaphylatoxin receptor.

The mouse C5a receptor gene was isolated using the human C5a receptor cDNA probe recently described (Gerard, N. P., and C. Gerard. 1991. Nature 349:614). By analogy with the human gene, the mouse homolog contains two exons with the 5' untranslated region and initiating methionine codon present in exon 1 and the remainder of the molecule in exon 2. Generation of an expressible cDNA for the mouse C5a receptor was accomplished using the polymerase chain reaction and a sense oligodeoxynucleotide primer which included an initiation codon just 5' to the sequence encoding the N-linked glycosylation site. When transfected into human 293 kidney epithelial cells the cloned cDNA directs expression of a binding site for human C5a anaphylatoxin with a binding constant of 2.5 +/- 0.3 nM; the human C5a receptor expressed under identical conditions has a Kd of 1.7 +/- 0.2 nM. Overall, the deduced amino acid sequences of the receptors are 65% identical given the analogous gene structures. Alignment of the sequences as seven transmembrane segment receptors reveals that the greatest structural diversity (approximately 70%) exists in the putative extracellular domains. In contrast, species differences among other members of this family of seven membrane-spanning receptors is generally only 10 to 20%, even for receptors whose ligands are relatively small and not expected to interact with sites on the extracellular surfaces. A high degree of structural identify is observed for the C5a receptors in the transmembrane segments and in all but one of the loops predicted to exist in the cytoplasm. Inasmuch as critical structures responsible for high affinity binding of the 74 amino acid polypeptide to both C5a receptors involve features conserved between species, these data provide the starting point for mutagenesis studies to determine the nature of the binding and activation sites for the chemotactic receptors. Additionally, these data provide a reagent for immunologic and molecular genetic studies on the role of C5a receptors in inflammatory models.     

THE INFLUENCE OF WATER STRESS ON STEM AND LEAF PHOTOSYNTHESIS IN GLYCINE MAX AND SPARTEUM JUNCEUM (LEGUMINOSAE)

Stem and leaf photosynthesis were measured in Glycine max var. essex (soybean) and Sparteum junceum (Spanish broom). The significance of stem photosynthesis to whole plant growth was evaluated by blocking stem photosynthesis with black straw sections. The growth of S. junceum was reduced by 18% when black straws were used in comparison to clear straws. The whole plant growth of G. max was not influenced by blocking the stem carbon contribution. Mean midday leaf photosynthesis was 12 μmol CO₂ m^–2 s^–1 and 17 μmol CO₂ m^–2 s^–1 for G. max and 5. junceum, respectively. Mean midday stem photosynthesis of S. junceum was 6.5 μmol CO₂ m^–2 s^–1; however, positive net photosynthesis did not occur in G. max stems. Water stress caused a proportionally greater decrease in leaf photosynthesis compared to that of stems during diurnal cycles of photosynthesis in S. junceum. As a result the contribution to canopy carbon gain by stem photosynthesis increased from 38% to 48% of the total plant carbon gain under reduced water availability.     

MRI metrics at the epicenter of spinal cord injury are correlated with the stepping process in rhesus monkeys

Clinical evaluations of long-term outcomes in the early-stage spinal cord injury (SCI) focus on macroscopic motor performance and are limited in their prognostic precision. This study was designed to investigate the sensitivity of the magnetic resonance imaging (MRI) indexes to the data-driven gait process after SCI. Ten adult female rhesus monkeys were subjected to thoracic SCI. Kinematics-based gait examinations were performed at 1 (early stage) and 12 (chronic stage) months post-SCI. The proportion of stepping (PS) and gait stability (GS) were calculated as the outcome measures. MRI metrics, which were derived from structural imaging (spinal cord cross-sectional area, SCA) and diffusion tensor imaging (fractional anisotropy, FA; axial diffusivity, λ_//), were acquired in the early stage and compared with functional outcomes by using correlation analysis and stepwise multivariable linear regression. Residual tissue SCA at the injury epicenter and residual tissue FA/remote normal-like tissue FA were correlated with the early-stage PS and GS. The extent of lesion site λ_///residual tissue λ_// in the early stage after SCI was correlated with the chronic-stage GS. The ratios of lesion site λ_// to residual tissue λ_// and early-stage GS were predictive of the improvement in the PS at follow-up. Similarly, the ratios of lesion site λ_// to residual tissue λ_// and early-stage PS best predicted chronic GS recovery. Our findings demonstrate the predictive power of MRI combined with the early data-driven gait indexes for long-term outcomes. Such an approach may help clinicians to predict functional recovery accurately.     

TEB/POLQ plays dual roles in protecting Arabidopsis from NO-induced DNA damage

Nitric oxide (NO) is a key player in numerous physiological processes. Excessive NO induces DNA damage, but how plants respond to this damage remains unclear. We screened and identified an Arabidopsis NO hypersensitive mutant and found it to be allelic to TEBICHI/POLQ, encoding DNA polymerase θ. The teb mutant plants were preferentially sensitive to NO- and its derivative peroxynitrite-induced DNA damage and subsequent double-strand breaks (DSBs). Inactivation of TEB caused the accumulation of spontaneous DSBs largely attributed to endogenous NO and was synergistic to DSB repair pathway mutations with respect to growth. These effects were manifested in the presence of NO-inducing agents and relieved by NO scavengers. NO induced G2/M cell cycle arrest in the teb mutant, indicative of stalled replication forks. Genetic analyses indicate that Polθ is required for translesion DNA synthesis across NO-induced lesions, but not oxidation-induced lesions. Whole-genome sequencing revealed that Polθ bypasses NO-induced base adducts in an error-free manner and generates mutations characteristic of Polθ-mediated end joining. Our experimental data collectively suggests that Polθ plays dual roles in protecting plants from NO-induced DNA damage. Since Polθ is conserved in higher eukaryotes, mammalian Polθ may also be required for balancing NO physiological signaling and genotoxicity.     

大雾岭保护区穿山甲冬季生境选择

1999年12月至2001年2月,对大雾岭自然保护区穿山甲冬季栖息地的选择进行了研究,结果表明对林型选择的先后次序为针阔混交林、灌木丛、常绿阔叶林、针叶林;最偏爱针阔混交林,最不喜爱针叶林.多选择陡坡(30～ 60°);干扰源距离较远(>1 000 m),干扰程度小;林下草灌层盖度高(81% ～ 100%),隐蔽程度好; 阳坡或半阴半阳坡;中低海拔(760 ～ 1 500 m);中下坡位;水源距离较近(<500 m);乔木郁闭度适中(31% ～ 70%)的生境.较少选择上坡位,林下草灌层中低(0 ～ 50%),乔木郁闭度偏高(71%～ 100%)或偏低(0～ 30%),阴坡的生境.对洞口设置的要求是多朝南,而且要求隐蔽条件好,多数为全隐蔽或半隐蔽;最不喜爱将洞口设置在裸露、隐蔽程度差的生境,强力避免洞口向北.坡度、干扰源距离和林下草灌层盖度是影响穿山甲冬季栖息地选择的关键环境因子.     

栗山天牛成虫羽化与温湿度的关系

栗山天牛Massicus raddei (Blessig)是危害我国东北辽东栎Quercus liaotungensis和蒙古栎Q.mongolicus天然林的重大害虫,生活周期长,3a发生1代,而且生活史整齐,在东北林区的辽宁、吉林和内蒙发育历期基本一致,因而绝大部分的成虫羽化时期出现在同一年份.为了有效防治栗山天牛,利用栗山天牛成虫具有趋光性这一特点,研究发明了诱集捕杀成虫的专用黑光灯,诱杀了大量的栗山天牛成虫,吉林省2008年共诱杀栗山天牛成虫达24.16t.根据每天晚上所诱到的栗山天牛的成虫数量(平均lkg栗山天牛成虫数量为430头,按此折合成重量kg统计),分析栗山天牛在成虫发生期其羽化数量与温湿度因子的关系.结果表明,栗山天牛成虫的羽化高峰期集中在7月下旬至8月上旬;成虫的羽化与林间气温呈显著的正相关关系,与相对湿度则呈显著负相关关系.研究对栗山天牛成虫的发生量与温湿度的关系进行了拟合.研究结果为我国东北林区栗山天牛成虫羽化年份预测预报成虫出现和发生期以及在成虫发生期开展防治提供了依据.     

高温强光胁迫对苹果果皮PPO活性的影响

苹果果实日烧是一种普遍发生的生理病害,最常见的特征之一就是在果实表面出现褐变。通常认为PPO与植物的酶促褐变密切相关。研究了自然和控制条件下,高温强光胁迫对果实PPO活性的影响,以便揭示高温强光胁迫下苹果果实褐变与PPO活性之间的联系。结果表明：高温和强光胁迫与果皮PPO活性变化密切相关。就树冠不同方位而言,西南方位是高温和强光胁迫最严重的区域,其外围裸露果实的PPO活性也最强。在一定范围内,随着处理温度和光照强度的升高,果皮PPO活性也逐渐增强。短时间剧烈升温能够引起PPO活性骤然上升。在同样程度的高温胁迫下,提高环境湿度有利于抑制果皮PPO活性,从而减轻褐变症状的发生。室内外试验一致证实：果实日烧褐变现象与高温强光胁迫下果皮组织PPO活性大幅度提高有直接关系。     

大兴安岭兴安落叶松(Larix gmelinii)天然林分级木转换特征

通过调查样地,作树干解析,分析了不同结构兴安落叶松天然林分级木（优势木、平均木和被压木）转换特征。研究表明：（1）不同结构的兴安落叶松天然林分级木转换年龄、方向和转换率均不同。兴安落叶松分级木转换率29.4%。分级木中,优势木、平均木和被压木转换率分别35.3%、41.2%、11.8%。分级木转换中,优势木与平均木相互转换比例较高,优势木转平均木占83.3%,平均木转优势木占85.7%;优势木向被压木转换比例仅为16.7%;被压木不能转换成优势木,只能转换成平均木,被压木中无转换占88.2%,在森林经营和抚育采伐中应考虑伐除这些被压木。（2）在林分年龄36～65a范围内,随着林分年龄增大,其转换率呈增加趋势。林分年龄30～39a、50～59a和60～69a时,其转换率分别0、33.3%和46.7%。（3）随着林分密度增加,分级木转换率呈增高趋势。当林分密度小于2500株.hm^-2时,主要于优势木与平均木间转换。当林分密度大于2500株.hm^-2时,才出现其它分级木与被压木相互转换现象。（4）不同林型分级木转换率和转换方向不同。草类-落叶松和杜香-落叶松林分级木转换率分别50%和9.5%。（5）不同水平格局林分分级木转换率不同。聚集分布和随机分布时,其转换率分别61.1%和13.3%。     

大长鼻白蚁有翅成虫的首次记述

首次发现并记述大长鼻白蚁Schedorhinotermes magnus Tsai et Chen,1963有翅成虫。大长鼻白蚁有翅成虫头壳近圆形,前胸背板长0.78-0.87 mm,体长7.99-8.54 mm。研究标本采集于广西壮族自治区南宁市,保存于南宁市白蚁防治所。