Evolution of burrow systems after the accidental introduction of a new earthworm species into a Swiss pre-alpine meadow

 The unintentional introduction of a new earthworm species (Aporrectodea nocturna) into a Swiss pre-alpine meadow resulted in a great increase in earthworm density in the newly colonized area (386 m^–2) compared with the density observed in the natural area (273 m^–2) where an earthworm community was already present. To investigate the impact of this introduction on the burrow systems, eight soil cores (length 25 cm, diameter 16 cm) were taken (four in the colonized area and four in the natural area) and analysed with computer-assisted X-ray tomography. The resulting images were processed to obtain the 3D-skeleton reconstructions of the earthworm burrow systems. Due to high variability in these burrow systems, only slight differences were observed between the two areas. The total burrow length and the mean burrow lengths tended to be greater in the colonized area. Moreover, the distribution of pore numbers with depth showed different patterns with a maximum for depths between 10 cm and 15 cm in the colonized area and a maximum for depths between 20 cm and 25 cm in the natural area. These differences may have been related to: (1) the particular behaviour of A. nocturna, which was observed to cast at the surface in this site, and (2) the predominance of juvenile earthworms around the colonization front. These differences were sufficient to create significant effects on the continuity of the burrow systems (assessed by the number of different pathways between virtual horizontal planes) for the two areas. The colonized area was characterized by a greater pore continuity, which could have resulted in enhanced transfer properties. Received: 2 July 1999     

鸡脯肉和鸡骨架制备鸡精原料的最佳工艺条件研究

[目的]建立一种利用鸡脯肉和鸡骨架制备鸡精原料的工艺简单、成本低、制得产品风味好的方法。[方法]以鸡脯肉和鸡骨架为原料,通过控制合适的原料配比和酶解工艺制备鸡精原料,提高呈现Kokumi风味并减少苦味肽的形成。[结果]分析表明,该试验的处理5的原料配比及酶解工艺制得的鸡精(鸡粉)原料香味及滋味多样,产品品质得到极大提高。[结论]研究解决了目前酶解单一底物存在的弊端,实现了在产品的鸡肉风味得到较大提升的同时,生产成本下降的效果。     

Osteosarcoma in the proximal humerus of a mare

A 15‐year‐old Quarter Horse mare was examined for significant and progressive lameness in the right front limb. On physical examination, muscle atrophy over the scapular and pectoral regions were noted. A pain response was elicited on palpation of the scapulohumeral joint. No other abnormalities were noted on examination of the limb. Diagnostic nerve blocks ruled out a source of lameness in the distal limb. Arthrocentesis of the scapulohumeral joint was performed and results were within normal limits. Radiographs of the right scapulohumeral joint revealed an extensive, aggressive bone lesion in the proximal humerus, suspected to be an osteosarcoma. After a course of nonsteroidal anti‐inflammatory therapy, minimal improvement to the lameness was noted. The owner elected to subject the horse to euthanasia due to the lack of significant response to treatment. Post mortem radiographic and histological examinations determined a definitive diagnosis of an osteosarcoma in the proximal humerus.     

基于最大正方形的玉米作物行骨架提取算法

为了满足现代农业精准施药技术中导航路径识别的需要,该文提出一种基于最大正方形的玉米作物行骨架提取算法。首先对采集到的田间玉米作物行图像进行灰度变换,采用改进的过绿灰度化算法使作物行与背景明显分割开来;然后通过滤波、阈值分割得到二值图像;而后对经过预处理后的二值图像进行形态学中的闭运算操作,得到玉米作物行的轮廓;最后利用最大正方形准则提取玉米作物行骨架。为了验证该算法的准确度,对提取的玉米作物行骨架进行直线拟合操作,利用拟合出的中央作物行线与实际导航线偏差的大小来判断骨架提取的精准度。试验结果表明,该算法能保持骨架像素的单一性,对边缘噪声具有很强的抗干扰能力,提取骨架的误差小于5 mm,能够满足玉米对行精准施药的需求。     

铰接式客车车身骨架轻量化研究

对某18 m低入口后置铰接式城市客车车身进行有限元分析获得车身强度分布情况,在此基础上,采用正交法和交互调整相结合的方法对车身骨架进行轻量化改进设计。对重要构件安排正交计算,进行不同工况水平下的多次计算,以轻量化为目标确定最佳的改进方案,对强度、刚度影响小的构件,则直接进行改进。优化后的轻量化模型满足客车的强度、刚度要求,且轻量化效果显著,为铰接式客车车身骨架的轻量化设计提供了参考依据。     

有机锌锰对蛋鸡种蛋中锌锰含量及子代胫骨发育的影响

试验旨在研究蛋鸡母体添加有机锌和有机锰对种蛋中锌锰含量及后代雏鸡骨骼发育的影响。选取23周龄、体重相近的健康海兰褐祖代种母鸡576只,随机分为3组,每组12个重复,每个重复16只鸡。对照组饲粮添加80 mg/kg的无机锌锰(来源:ZnSO4、MnSO4),等量添加组饲粮用40 mg/kg的有机锌锰(来源:氨基酸锌、锰)替换对照组饲粮等量的无机锌和无机锰,额外添加组饲粮在对照组饲粮的基础上添加40 mg/kg有机锌、锰,试验第8、24周测定种蛋中锌锰含量,试验第31周所产种蛋入孵。检测1日龄雏鸡的胫骨发育情况。结果表明:种鸡饲粮中添加有机锌锰显著提高了蛋黄和胫骨中的锰沉积量(P<0.05);试验第23周,等量添加组雏鸡的胫骨长度显著高于对照组和额外添加组(P<0.05);试验第31周,等量添加组雏鸡的胫骨重显著低于对照组(P<0.05)。因此,种鸡饲粮等量添加有机和无机锌锰能促进锰在蛋黄和后代胫骨中的沉积,促进骨骼发育。     

尖吻鲈仔鱼骨骼发育观察

掌握尖翅燕鱼 (Platax teira) 仔稚鱼脊柱及附肢骨骼系统的发育时序特征,可为其苗种繁育、环境适应及分类鉴定提供理论依据。采用软骨-硬骨双染色法对尖翅燕鱼仔稚鱼 [0~30日龄 (dah)] 脊柱、胸鳍、腹鳍、背鳍、臀鳍以及尾鳍进行染色观察与分析。结果表明,尖翅燕鱼有24枚脊椎骨,尾部骨骼由5枚尾下骨和2枚尾上骨构成,附肢支鳍骨的发育顺序为胸鳍、腹鳍、尾鳍、臀鳍和背鳍。尖翅燕鱼在初孵仔鱼已具备胸鳍支鳍骨原基和脊索,4 dah仔鱼胸鳍和腹鳍最先发育;7 dah仔鱼髓弓、脉弓开始出现;13 dah仔鱼骨骼形态和数量基本稳定;26 dah左右稚鱼开始骨化,脊柱和脊椎最先完成骨化;30 dah进入幼鱼阶段,其外表形态已经固定,与成鱼无异,典型特征为头部、躯干部和尾部各有3条黑色条带,身体呈雪白银色,受到外界刺激时体色瞬间变为黑色。尖翅燕鱼脊柱及附肢骨的发育顺序与其他海水鱼基本一致,但骨骼发育时间节点和数量有所不同。     

鮸鱼仔鱼摄食功能骨骼早期发育研究

采用硬骨-软骨双染色技术,详细地研究了鲵鱼仔鱼各发育阶段摄食功能骨骼的形态发育和骨化特征.在孵化后至4日龄(体长3.0 mm)仔鱼,舌弓、鳃弓、悬骨系以软骨形式,而鳃盖骨系、上下颌则以纤维化骨质逐步出现并相继硬骨化,至34日龄(7.8 mm)仔鱼,除方骨、后翼骨和中翼骨外,其它骨骼完全硬骨化.研究结果表明:鮸鱼仔鱼摄食器官的骨骼在短时间内硬骨化,为开始主动摄食提供了必要条件,表明仔鱼阶段已具备了摄食能力.     

Inhibitory effects of septin 2 gene silencing induced by siRNA on migration of human colorectal cancer cell line LoVo

AIM:To investigate the expression of septin 2 in human colorectal cancer cell lines and the effect of septin 2 on the capacity of migration of human colorectal cancer cell line LoVo. METHODS:Real-time fluorescence quantitative RT-PCR and Western blotting analysis were used to determine the mRNA and protein levels of septin 2 in different metastatic potential cell lines, respectively. The expression of septin 2 in LoVo cells was silenced by siRNA. The efficacy of siRNA was confirmed by real-time fluorescence quantitative RT-PCR. Septin 2 and its co-localization with F-actin were measured by immunofluorescence method. The migration of transfected cells was analyzed by scratch test. RESULTS:The expression of septin 2 in LoVo cells was significantly higher than that in low metastatic potential cell lines such as SW480, HCT-116 and HT-29 at both mRNA and protein levels. The mRNA expression of septin 2was successfully silenced in LoVo cells by siRNA. Cell wound closure rate was also decreased in septin 2 siRNA group as compared with control group(both P<0.05). The co-expression of septin 2 and F-actin formed the typical filamentous-granular organization, and down-regulation of septin 2 resulted in cell skeleton disturbance with less or shorter pseudopodium and decreased stress fibers. CONCLUSION:Septin 2 is highly expressed in LoVo cells. Partial deletion of septin 2 represses the capability of tumor cell migration.