The neural activities of the greater superficial petrosal nerve of the rat in response to chemical stimulation of the palate

A comparison of the integrated responses of the rat's greatersuperficial petrosal (GSP) and chorda tympani (CT) nerves toa number of taste stimuli was studied. The GSP nerve of therat was very responsive to the chemical stimulation of the oralcavity. Among the selected stimuli related to the four basictaste qualities, 0.5 M sucrose produced the greatest neuralresponse in the GSP nerve, whereas, 0.1 M NaCl produced thegreatest in the CT nerve. The GSP nerve integrated responseto 0.5 M sucrose solution was approximately three times as greatin magnitude as that to a 0.1 M NaCl solution. The neural responsemagnitude of the GSP and CT nerves were as follows: GSP nerve;0.5 M sucrose >0.02 M Na-saccharin >0.05 M citric acid>0.1 M NaCl > 0.01 M quinine-HCl. CT nerve; 0.1 M NaCl> 0.05 M citric acid > 0.02 M Na-saccharin > 0.01 Mquinine-HCl >0.5 M sucrose. The response magnitudes of theGSP nerve to 0.3 M chloride salt solutions were: LiCl > CaCl₂> NaCl > NH₄Cl > KCl, whereas the response magnitudesof the CT nerve to the above salts were: LiCl > NaCl >NH₄Cl > CaCl₂ > KCl. All 0.5 M solutions of the selectedsugars (sucrose, rhamnose, galactose, lactose, fructose, -methyl-D-glucoside,xylose, mannose, arabinose, maltose, sorbose and glucose) evokedneural responses in both GSP and CT nerves. The order of theresponse magnitudes of the GSP nerve to the selected sugarswas similar to that of the CT nerve but the absolute magnitudesof the GSP nerve were greater.     

A Cluster of Cuticle Protein Genes of Drosophila Melanogaster at 65a: Sequence, Structure and Evolution

A 36-kb genomic DNA segment of the Drosophila melanogaster genome containing 12 clustered cuticle genes has been mapped and partially sequenced. The cluster maps at 65A 5-6 on the left arm of the third chromosome, in agreement with the previously determined location of a putative cluster encompassing the genes for the third instar larval cuticle proteins LCP5, LCP6 and LCP8. This cluster is the largest cuticle gene cluster discovered to date and shows a number of surprising features that explain in part the genetic complexity of the LCP5, LCP6 and LCP8 loci. The genes encoding LCP5 and LCP8 are multiple copy genes and the presence of extensive similarity in their coding regions gives the first evidence for gene conversion in cuticle genes. In addition, five genes in the cluster are intronless. Four of these five have arisen by retroposition. The other genes in the cluster have a single intron located at an unusual location for insect cuticle genes.     

干扰素研究及应用进展

1957年,英国科学家Isaacs和Lindenmann利用鸡胚绒毛尿囊研究流感干扰现象时,发现一种能够干扰病毒繁殖的物质,称之为干扰素（IFN）,由于干扰素对许多疾病有很好的治疗作用,一直是医学领域研究的重要物质之一。现在干扰素已成功地用于肝炎、肿瘤治疗等方面。为了充分发挥干扰素的作用,人们稍用基因工程的方法来对干扰素的产量及功效进行改进,已达到更好的应用,因此基因工程干扰素越来越多地成了研究的重点。     

人热休克蛋白gp96基因的克隆及其在大肠杆菌中的表达与纯化

热休克蛋白gp96是热休克蛋白90家族成员,能够引起非特异性和特异性免疫反应。得到大量高纯度的蛋白质是研究开发gp96的关键。然而重组的gp96容易在E．coli中降解,并在一定条件下形成多聚体。实验先将人gp96基因克隆到pET-30a载体上并在E．coli Blstar中表达,再经过亲和层析、阴离子交换、分子筛分别纯化gp96。最终去掉了大部分的降解片段和多聚体,得到一定量的可溶性gp96,为进一步研究其结构和功能打下一定的基础。     

Presence of Quorum-Sensing-Mediated Gene Regulation in Pathogenic Ice-Nucleation-Active (INA) Bacteria

Nine out of a total of 20 pathogenic ice-nucleation-active bacteria, with different levels of inducible INA, were tested and found positive for their ability to synthesize quorum-sensing (QS) signals. The bacteria were isolated from willow plants and belonged to the genera Bacillus, Erwinia, Pseudomonas and Sphingomonas. As reporter bacteria, to detect the homoserine lactone (HSL) autoinducer, Agrobacterium tumefaciens, Chromobacterium violaceum, Pseudomonas aeroginosa, Aeromonas hydrophila and Vibrio fischeri strains were used. We thus provide evidence that pathogenic ice-nucleation bacteria with inducible INA produce QS signals that in other bacteria have been shown to be in the control of genes of importance for pathogenicity.     

Green algae from the Lower Cretaceous carbonate of northern Shiraz (Zagros Mountains,SW Iran)

In northern Shiraz (SW Iran), Lower Cretaceous carbonate was studied in detail. In this study, nine species of dasycladacea algae were classified. There are different species of dasycladacea algae which belong to seven different genera: Actinoporella, Cylindroporella, Dissocladela, Heteroporella, Neomeris, Salpingoporella, Trinocladus; one species of udoteaceae belongs to Bouenia; one species of acetabulariaceae belongs to Clypeina and the microproblematicum Coptocampylodon was also seen. Among the green algae, dasycladaceae and acetabulariceae are the most frequent and udoteaceans are rare in Zagros Mountains. The genus of Trinocladus is a new record for Lower Cretaceous (Upper Albian) in SW Iran.     

Examination of Duct Physiology in the Human Mammary Gland

BackgroundThe human breast comprise several ductal systems, or lobes, which contain a small amount of fluid containing cells, hormones, proteins and metabolites. The complex physiology of these ducts is likely a contributing factor to the development of breast cancer, especially given that the vast majority of breast cancers begin in a single lobular unit.MethodsWe examined the levels of total protein, progesterone, estradiol, estrone sulfate, dehydroepiandrosterone sulfate, and macrophages in ductal fluid samples obtained from 3 ducts each in 78 women, sampled twice over a 6 month period. Samples were processed for both cytological and molecular analysis. Intraclass correlation coefficients and mixed models were utilized to identify significant data.ResultsWe found that the levels of these ductal fluid components were generally uncorrelated among ducts within a single breast and over time, suggesting that each lobe within the breast has a distinct physiology. However, we also found that estradiol was more correlated in women who were nulliparous or produced nipple aspirate fluid.ConclusionsOur results provide evidence that the microenvironment of any given lobular unit is unique to that individual unit, findings that may provide clues about the initiation and development of ductal carcinomas.     

Biodeterioration of Mayan buildings at uxmal and tulum,Mexico

Uxmal and Tulum are two important Mayan sites in the Yucatan peninsula. The buildings are mainly composed of limestone and grey/black discoloration is seen on exposed walls and copious greenish biofilms on inner walls. The principal microorganisms detected on interior walls at both Uxmal and Tulum were cyanobacteria; heterotrophic bacteria and filamentous fungi were also present. A dark‐pigmented mitosporic fungus and Bacillus cereus, both isolated from Uxmal, were shown to be acidogenic in laboratory cultures. Cyanobacteria belonging to rock‐degrading genera Synechocystis and Gloeocapsa were identified at both sites. Surface analysis previously showed that calcium ions were present in the biofilms on buildings at Uxmal and Tulum, suggesting the deposition of biosolubilized stone. Apart from their potential to degrade the substrate, the coccoid cyanobacteria supply organic nutrients for bacteria and fungi, which can produce organic acids, further increasing stone degradation.