Benzyl esters in the gas-chromatographic purification of radioactive acetic acid from bacteria, and for the possible analysis of other short-chain acids

A method has been developed for the purification of small quantities of acetic acid from bacteria. The acetic acid, with added carrier and a second isotopic species as an internal standard, was extracted into diethyl ether, the benzyl ester was formed using diazotoluene (phenyldiazomethane) and the resultant benzyl acetate purified by small-scale preparative gas-liquid chromatography on a nonpolar stationary phase. Overall recoveries were in the range 26–40%. The method was extended to show the feasibility of the preparative purification of other short chain acids, and also for the analysis of C₁ to C₁₀ acids, as their benzyl esters.     

激光及γ射线对有丝分裂染色体畸变感应现象的比较

波长514nm的激光照射可用于研究激光导致有丝分裂染色体畸变的效应。本文提供了一种新的辐照系统,能用于研究突变的感应现象,并与从γ-线辐射源获得的结果进行了比较。 Abstract:Laser irradiation at wavelength 514 nm was used to study the effect of lasers in inducing chromosomal aberrations at mitosis.This study offers a new radiation system which could be used for the induction of mutations.Results are compared with those obtained from studies using γ-rays as irradiation source.     

A brief overview of amyloids and Alzheimer’s disease

Amyloid fibrils are self-assembled fibrous protein aggregates that are associated with a number of presently incurable diseases such as Alzheimer’s and Parkinson’s disease. Millions of people worldwide suffer from amyloid diseases. This review summarizes the unique cross-β structure of amyloid fibrils, morphological variations, the kinetics of amyloid fibril formation, and the cytotoxic effects of these fibrils and oligomers. Alzheimer’s disease is also explored as an example of an amyloid disease to show the various approaches to treat these amyloid diseases. Finally, this review investigates the nanotechnological and biological applications of amyloid fibrils; as well as a summary of the typical biological pathways involved in the disposal of amyloid fibrils and their precursors.     

(+)-ABA content and lipid deposition in interior spruce somatic embryos

Summary Interior spruce (Picea glauca engelmannii complex) somatic embryos grown on 48 μmol (±)-ABA per L over a period of 42 d without transfer underwent precocious germination by 49 d. Those transferred at 28 d to fresh medium with 48 μmol (±)-ABA continued embryo development until harvested at 56 d; the transfer at 28 d resulted in an increase in embryo lipid content after 42 d. Somatic embryos grown under this condition contained 181.4±41.2, 116.0±42.4, and 91.8±33.6 ng (+)-ABA per mg of lyophilized tissue at 42, 49, and 56 d, respectively. By comparison, embryos grown without the transfer at 28 d had 86.8±25.4 ng (+)-ABA per mg of lyophilized tissue at 42 d, just prior to precocious germination. After 3 weeks’ storage in a drying chamber under high humidity, the (+)-ABA content of 56-d-old transferred embryos decreased to 15.4 ± 4.4 ng (+)-ABA per mg of lyophilized tissue. The increased lipid content resulting from embryo transfer and the reduction in internal (+)-ABA content during storage are factors which will contribute to improved conversion of somatic embryos to plantlets.     

禽流感H5N1病毒感染BALB/c小鼠后多器官病变初探

为了研究禽流感H5N1病毒在各个器官的增殖和病理变化,在生物安全实验室,我们将禽流感H5N1病毒通过尾静脉接种BALB/C小鼠。结果小鼠在不经过适应的情况下,直接感染发病,甚至死亡。在观察的7天内,感染小鼠临床症状主要表现呼吸急促,体温、体重下降。尸检表现肺出血,心外膜坏死以及肝脏的坏死。组织病理检查表现心、肝、肺等多器官的病变。肺的病变伴有纤维化的弥漫性肺泡损伤;心肌外膜大量淋巴细胞浸润、坏死;肝细胞大量坏死,淋巴细胞浸润。心、肝的坏死病变在H5N1禽流感病毒相关的研究中未见报道。经过对各个组织器官的病毒载量的检测,未发现病毒在各个病变组织中的复制。免疫组化的检测,各个组织中也未检出阳性的细胞反应。因此,我们认为H5N1禽流感病毒感染小鼠引起多个器官组织的损伤,甚至死亡,不是病毒在器官的复制,而可能是病毒感染小鼠,产生炎症细胞因子的高度表达,损伤多个器官组织所致。     

Hydrodynamic trapping in the formation of the chlorophyll a peak in turbid, very low salinity waters of estuaries

In the James River Estuary, a chlorophyll peak occurred in verylow salinity waters (0.5) during periods of low river dischargein the summer and fall. The biomass of phytoplankton, as measuredby chlorophyll concentration, was 5–10 times that formedin adjacent areas further up-and downstream. Comparisons betweenthe peak area and the 2 area for net plankton biomass, biogenicsilica, phaeopigments, POC/PON ratios and microscopic observationindicated the peak biomass was largely composed of high concentrationsof physiologically healthy freshwater diatoms. We applied equationsfor particle sinking rates to diatoms observed in the JamesRiver and compared these rates with calculations of upward verticalwater velocity. During periods of low river discharge (summerand fall) the sinking rate of diatoms in the chlorophyll peakclosely balanced the net upward water velocity, thereby selectivelytrapping diatoms in the very low salinity zone. The turbiditymaximum increased in intensity and moved downriver in winterand spring due to high river discharge. As upward water velocityincreases, phytoplankton are never able to attain a criticalbiomass and are swept downestuary. This seasonally changingplant biomass is significant to food chain and geochemical considerationsof estuaries. ¹Present address: Department of Oceanography, National FisheriesUniversity of Pusan, Korea     

STEROLS OF 14 SPECIES OF MARINE DIATOMS (BACILLARIOPHYTA)1

The sterol compositions of 14 species of marine diatoms were determined by gas chromatography and gas chromatography-mass spectrometry. A variety of sterol profiles were found. The sterols 24-methylcholesta-5,22E-dien-3β-ol, cholest-5-en-3β-ol, and 24-methylcholesta-5,24(28)-dien-3β-ol, previously described as the most common sterols found in diatoms, were major sterols in only a few of the species. In light of this and other recent data, it is clear that these three sterols are not typical constituents of many diatom species. Most of the centric species examined had 24-methylcholesta-5,24(28)-dien-3β-ol and 24-methylcholest-5-en-3β-ol as two of their major sterols. The exception was Rhizosolenia setigera, which possessed cholesta-5,24-dien-3β-ol as its single major sterol. In contrast to the centric species, the pennate diatoms examined did not have any particular sterols common to most species. Minor levels ofΔ⁷-sterols, rarely found in large amounts in diatoms, were found in four species. C₂₉sterols were found in many species; seven contained 24-ethylcholest-5-en-3β-ol and three contained 24-ethylcholesta-5,22E-dien-3β-ol, reinforcing previous suggestions that C₂₉ sterols are not restricted to higher plants and macroalgae. 24-Ethylcholesta-5,22E-dien-3β-ol may prove to be useful for taxonomy of the genus Amphora and the order Thalassiophysales. A major sterol of Fragilaria pinnata was the uncommon algal sterol 23,24-dimethylcholesta-5,22E-dien-3β-ol. Cholesta-5,24-dien-3β-ol was the only sterol found in the culture of Nitzschia closterium. This differed from previous reports of 24-methylcholesta-5,22E-dien-3β-ol as the single major sterol in N. closterium. Two C₂₈ sterols possessing an unusual side chain were found in Thalassi-onema nitzschioides, a C_28:2 sterol (16%) and a C_28:1 sterol in lower abundance (2.5%), which may be 23-methylcholesta-5,22E-dien-3β-ol and 23-methyl-5α-cholest-22E-en-3β-ol, respectively. The species Cylindrotheca fusiformis, T. nitzschioides, and Skeletonema sp. may be useful as direct sources of cholesterol in mariculture feeds due to their moderate to high content of this sterol.     

In Vivo Analysis of Saccharomyces Cerevisiae Cox2 mRNA 5''-Untranslated Leader Functions in Mitochondrial Translation Initiation and Translational Activation

We have used mutational and revertant analysis to study the elements of the 54-nucleotide COX2 5'-untranslated leader involved in translation initiation in yeast mitochondria and in activation by the COX2 translational activator, Pet111p. We generated a collection of mutants with substitutions spanning the entire COX2 5'-UTL by in vitro mutagenesis followed by mitochondrial transformation and gene replacement. The phenotypes of these mutants delimit a 31-nucleotide segment, from -16 to -46, that contains several short sequence elements necessary for COX2 5'-UTL function in translation. The sequences from -16 to -47 were shown to be partially sufficient to promote translation in a foreign context. Analysis of revertants of both the series of linker-scanning alleles and two short deletion/insertion alleles has refined the positions of several possible functional elements of the COX2 5'-untranslated leader, including a putative RNA stem-loop structure that functionally interacts with Pet111p and an octanucleotide sequence present in all S. cerevisiae mitochondrial mRNA 5'-UTLs that is a potential rRNA binding site.     

Variability in maturation and germination from white spruce somatic embryos,as affected by age and use of solid or liquid culture

Summary The yield of morphologically normal Stage 3 somatic embryos of white spruce [Picea glauca (Moench) Voss], and subsequent germinability, was affected by culture age and use of solid and/or liquid culture growth conditions. Of the conditions that were compared, best results were obtained with cultures up to 3 yr old that had been continuously grown in liquid medium. Such material yielded up to 374 morphologically normal Stage 3 embryos per g f. wt. inoculum, when routinely pretreated using a 1 wk 2,4-dichlorophenoxyacetic acid-free period before maturation. By comparison the continual use of solid culture conditions resulted in lower yields (5/g f. wt. inoculum), and the use of solid medium in combination with liquid medium showed a greater affect of age on the production of normal Stage 3 embryos (348/g f. wt at 1.5 yr down to 19/g f. wt. at 3 yr) over the age range tested. In the absence of culture pretreatment, the oldest liquid cultures yielded only 44 normal Stage 3 embryos/g f. wt. inoculum, and the comparable solid to liquid cultures yielded 1.3/g f. wt. inoculum. The number of aberrant Stage 3 embryos in older cultures was reduced as a result of culture pretreatment; for example, in the oldest liquid cultures these represented 83% of the Stage 3 embryo population without pretreatment and 45% with pretreatment. Normal Stage 3 somatic embryo yield and germination characteristics (radicle and epicotyl development) were informative in distinguishing among the conditions studied. Germination characteristics were especially important when maturation responses were incapable of distinguishing among age classes. NRCC Contribution no. 38462.