Cloning and restriction fragment length polymorphism analysis of a cDNA for swine PIT-1, a gene controlling growth hormone expression*

A partial swine cDNA which encodes the functional domain of PIT-1 was isolated by the polymerse chain reaction (PCR). The swine PIT-1 cDNA clone is 95% identical at the protein level to the rat Pit-1 gene. Thus, Pit-l's known function in control of rat growth hormone and prolactin expression is likely to be conserved in swine. This swine cDNA clone was used to investigate genetic variability at PIT-1 in several American and Chinese breeds. Polymorphic BamIII fragments were found in pure-bred Meishan animals (n= 13), but only monomorphic fragments in five American breeds (n= 36).     

Endocytosis and Exocytosis Events Regulate Vesicle Traffic in Endothelial Cells

We used water-soluble styryl pyridinium dyes that fluoresce at the membrane-water interface to study vesicle traffic in endothelial cells. Cultured endothelial cells derived from bovine and human pulmonary microvessels were incubated in styryl probes, washed to remove dye from the plasmalemmal outer face, and observed by digital fluorescence microscopy. Vesicles that derived from plasmalemma by endocytosis were filled with the styryl dye. These vesicles were distributed throughout the cytosol as numerous particles of heterogeneous diameter and brightness. Vesicle formation was activated 2-fold following addition of extracellular albumin whereas a control protein, immunoglobulin G, had no effect. Dye uptake was abrogated by labeling at low temperatures and inhibitors of phosphoinositide-3-kinase (PI 3-kinase). Tyrosine kinase inhibitors (genistein and herbimycin A) prevented the albumin-induced vesicle formation. Cytochalasin B prevented vesicle redistribution indicating involvement of actin filaments in translocation of endosomes away from sites of vesicle formation. Styryl dye was lost from cells by exocytosis as evident by the disappearance of discrete fluorescent particles. N-ethylmaleimide and botulinum toxin types A and B caused cells to accumulate increased number of vesicles suggesting that exocytosis was regulated by NSF-dependent SNARE mechanism. The results suggest that phosphoinositide metabolism regulates endocytosis in endothelial cells and that extracellular albumin activates endocytosis by a mechanism involving tyrosine phosphorylation, whereas exocytosis is a distinct process regulated by the SNARE machinery. The results support the hypothesis that albumin regulates its internalization and release in vascular endothelial cells via activation of specific endocytic and exocytic pathways.     

Detection of cyanobacterial sxt genes and paralytic shellfish toxins in freshwater lakes and brackish waters on Åland Islands,Finland

Harmful cyanobacteria are a globally growing concern. They produce a large variety of toxic compounds, including saxitoxin and its many structural variants, a group of potent neurotoxins collectively called paralytic shellfish toxins or PST. Nucleic acid based detection methods, such as qPCR, have been proposed as potential screening and monitoring tools for toxic cyanobacteria, but it is not clear how well the presence and quantity of saxitoxin biosynthesis (sxt) genes can be used to predict the production of PST in the environment. In this study, the prevalence of three sxt genes and their co-occurrence with paralytic shellfish toxins in the environment was investigated. The sxtA, sxtG and sxtB genes were present on average in 31% of the samples collected from lakes and brackish coastal waters on Åland Islands, Finland, during the three-year monitoring period. PST detection frequency varied from 13% to 59% from year to year, and concentrations were generally low. On average higher sxtB copy numbers were associated with PST detection, and although a positive correlation between gene copy numbers and toxin concentrations was observed (Spearman rank correlation, ρ = 0.53, P = 0.012), sxt gene presence or quantity didn’t reliably predict PST production. Sequencing of sxtA fragments and identification of main cyanobacteria indicated that the likely candidate responsible for PST production in the samples belonged to the genus Anabaena.     

Conventional and Molecular Identification of Bacteria with Magnesite Enrichment Potential from Local Quarries in Erzurum

In this study, the bacteria having ore enrichment potential were isolated from three different magnesite quarries located in Erzurum-Askale borderlines. The obtained isolates were identified and characterized according to the conventional (morphological, physiological and biochemical tests) and molecular techniques (fatty acid methyl ester profiles (FAME), BOX PCR and 16S rDNA). According to sequence analysis, they were determined as Exiguobacterium aurantiacum (4), Exiguobacterium sibiricum (2), Bacillus sp. (2), Staphylococcus epidermidis (2), Staphylococcus haemolyticus (1), Shewanella baltica (1) and Klebsiella oxytoca (1), respectively.     

Fairy wrasses perceive and respond to their deep red fluorescent coloration

Fluorescence enables the display of wavelengths that are absent in the natural environment, offering the potential to generate conspicuous colour contrasts. The marine fairy wrasse Cirrhilabrus solorensis displays prominent fluorescence in the deep red range (650–700 nm). This is remarkable because marine fishes are generally assumed to have poor sensitivity in this part of the visual spectrum. Here, we investigated whether C. solorensis males can perceive the fluorescence featured in this species by testing whether the presence or absence of red fluorescence affects male–male interactions under exclusive blue illumination. Given that males respond aggressively towards mirror-image stimuli, we quantified agonistic behaviour against mirrors covered with filters that did or did not absorb long (i.e. red) wavelengths. Males showed significantly fewer agonistic responses when their fluorescent signal was masked, independent of brightness differences. Our results unequivocally show that C. solorensis can see its deep red fluorescent coloration and that this pattern affects male–male interactions. This is the first study to demonstrate that deep red fluorescent body coloration can be perceived and has behavioural significance in a reef fish.     

Denaturing gradient gel electrophoresis detection of polymorphism in a PCR fragment of sheep epidermal growth factor gene

The ovine map is not yet well-developed, which represents a problem when looking for markers of a region of interest in sheep. A means of circumventing this is to use comparative mapping. In this study primers were determined using consensus sequences for the epidermal growth factor gene of humans, rats and mice, and an ovine epidermal growth factor gene fragment was amplified by polymerase chain reaction (PCR). A new set of specific ovine primers was chosen to study the polymorphism of this DNA fragment by denaturing gradient gel electrophoresis. Eighty-four individuals belonging to seven sheep breeds were studied with this technique and four alleles were detected. The heterozygosity rate was 0.57. Family analysis showed mendelian inheritance of the alleles. Usually, genetic analysis of type-I loci used in the comparative mapping is based on the detection of restriction fragment length polymorphisms in sheep DNA using cDNA probes from other species. Our work shows that another method, based on PCR and denaturing gradient gel electrophoresis techniques, can be efficiently used.     

城市景观生态风险评估框架与实践——以北京天坛地区为例

当前，城市景观生态风险研究缺少科学合理、方便实用的评估框架。作者基于景观生态风险评估基本范式，明确了城市景观生态服务价值的测算方法，分析了引起生态损害的自然因素和人类活动因素，形成了城市景观生态风险评估的技术框架和参数体系；继而以北京天坛地区为研究区，开展了典型城市景观生态风险的定量评估。结果表明：（1）天坛地区景观生态价值总量约为2.41亿元。区域的历史文化价值最高，教育和美学景观价值紧随其后。（2）城市景观生态受损概率呈现"北高南低"的空间分布格局。生态受损概率的高值区面积占整个区域总面积的22.2%，主要分布在珠市口、磁器口和崇文门附近区域。（3）城市景观生态风险呈现"北低南高"的空间分布格局。高风险区主要分布在天坛公园内的文物建筑周边。本研究提供了一个可参考的城市景观生态风险评估应用框架，对生态风险评估中的不确定性进行了讨论，研究针对天坛案例区的具体结论有助于城市管理者避免潜在的风险。     

Molecular fingerprinting of peppermint (Mentha piperita) and some Mentha hybrids by sequencing and RFLP analysis of the 5S rRNA Non-Transcribed Spacer (NTS) region

Hybridization of species belonging to the genus Mentha is quite common. However, the indicators of hybridity are many and make Mentha hybrids' identification difficult. By using the same molecular strategy that allowed us to unequivocally identify some Mentha species, we amplified the Not-Transcribed-Spacer (NTS) of the 5S-rRNA gene to characterize the industrial crop peppermint, M. × piperita and some important Mentha interspecific hybrids: M. × dalmatica, M. × dumetorum, M. × rotundifolia, M. × maximilianea, M. × smithiana, M. × verticillata, M. × villosa. DNA amplification, sequence and cluster analysis revealed differences in the 5S-rRNA NTS region of Mentha hybrids. Peppermint and all other hybrids were unequivocally discriminated by RFLP analysis by using TaqI restriction enzyme, while a further discrimination between M. × dumetorum and M. × verticillata was obtained by XhoI restriction enzyme. Essential oil composition showed clustering patterns similar to DNA fingerprint, with a clear discrimination between plants producing menthofuran (e.g. M. aquatica and its related hybrids, including peppermint) and those containing piperitenone oxide (M. longifolia and its related hybrids).