Separation of methylated nucleosides by high-pressure liquid chromatography: The pattern of tRNA methylation in stimulated rat lymphocytes

An analytical method has been developed for the quantitative analysis of radiolabeled methyl ribonucleosides derived from transfer ribonucleic acids. The technique utilizes QAE-Sephadex in the borate form to separate 17 ribosides into three groups: quaternary base-methylated, sugar-O-methylated, and nonquaternary base-methylated nucleosides. The components of each group are subsequently separated on a strong cation-exchange resin of the polystyrene-divinyl-benzene type with baseline resolution for 14 species. Quantitative analysis is effected by counting column effluent fractions in a scintillation spectrometer.     

Functional characteristics of in vitro generated macrophages: a transient refractory state precedes reinducibility of a spatially restricted, possibly contact-dependent, cytostatic mechanism

Adherent layers of macrophages (M phi-c) generated in vitro from splenic precursors previously have been shown to inhibit proliferation of normal and neoplastic cells by mechanisms that do not involve the secretion of significant quantities of prostaglandins, peroxides, or proteases. In the current report, it is demonstrated that the effective range of the cytostatic effect of adherent M phi-c is so low that cytostasis can be circumvented by preventing the target cells from settling to the adherent layer by incubating the cultures of targets and M phi-c on a rocking platform. Despite the paucity of production of inhibitory mediators, the M phi-c do produce sufficient IL-1 to restore IL-2 production capacity to macrophage-depleted lymphocyte populations. The cytostatic activity of the M phi-c is an inducible event and remains for several days in the continuous presence of mitogen-activated lymphocytes or LPS + lymphokines. Once the activators are removed the cytostatic activity rapidly declines, reaching background levels in 24-48 hr. Maximal cytostatic activity can be reinduced but only 48 hr or longer after the primary activators were removed. A transient period in which the M phi-c are refractory to reactivation can be demonstrated to exist for 1-2 days after removal of the primary activators.     

Identification of novel RPGR (retinitis pigmentosa GTPase regulator) mutations in a subset of X-linked retinitis pigmentosa families segregating with the RP3 locus

The X-linked form of retinitis pigmentosa (XLRP) is a severe disease of the retina, characterised by night blindness and visual field constriction in a degenerative process, culminating with complete loss of sight within the third decade of life. Genetic mapping studies have identified two major loci for XLRP: RP3 (70%–75% of XLRP) and RP2 (20%–25% of XLRP). The RPGR (retinitis pigmentosa GTPase regulator) gene has been cloned within the RP3 genomic interval and it has been shown that 10%–20% of XLRP families have mutations in this gene. Here, we describe a single-strand conformational polymorphism-based mutation screening of RPGR in a pool of 29 XLRP families for which the disease segregates with the RP3 locus, in order to investigate the proportion of RP3 families with RPGR mutations and to relate the results to previous reports. Five different new mutations have been identified: two splice site mutations for exon 1 and three frameshift mutations in exons 7, 10 and 11. The percentage of RPGR mutations identified is 17% (5/29) in our genetically well-defined population. This figure is comparable to the percentage of RP2 gene mutations that we have detected in our entire XLRP patient pool (10%–15%). A correlation of RPGR mutations with phenotype in the families described in this study and the biochemical characterisation of reported mutations may provide insights into the function of the protein. Electronic Publication     

An analytical method for the separation of dopamine metabolites in cellular extracts by high-pressure liquid chromatography

An analytical scheme using high-performance liquid chromatography (HPLC) has been developed to separate radiolabeled catecholamines in cell extracts derived from mammalian cells grown in tissue culture. Four different types of chromatographic systems have been employed to effect separations of groups of metabolites that possess similar organic functional groups. Data obtained by thin-layer chromatography are also presented and it is demonstrated that HPLC is the system of choice for the separation and quantitative analysis of metabolites of dopamine in physiological fluids.     

Attractiveness of the maleAcheta domestica calling song to females

Summary FemaleAcheta domestica did not discriminate between pairs of model calling songs (CSs) which differed only in syllable period (SP; Fig. 1). The females selected the louder CS (Fig. 2) or the CS with a faster chirp rate (CR; Fig. 3) when presented with pairs of otherwise identical CSs. A CS with an SP of 50 ms (modal for the male's CS) was preferred when it was 5 dB louder than one with a 60-ms SP while a CS with a 60-ms SP was only consistently chosen when it was 10 dB louder than a CS with a 50-ms SP (Fig. 4). A more intense CS was preferred by the females regardless of whether its CR was faster or slower than that of the CS produced at a lower intensity (Fig. 6). When CSs with SPs of 50 or 60 ms had several different CRs, the females that made a significant choice preferred a CS with a 50-ms SP regardless of whether it was produced at a faster or slower CR (Figs. 7, 8). No significant selection between CSs with 40- and 50-ms SPs resulted when they were produced at different intensities (Fig. 5) or CRs (Fig. 9). Females only significantly chose a CS with a 50-ms SP over those with 40 ms SPs when the 50-ms-SP CS was louder and produced at a different CR (Fig. 10). From these results, it was apparent that SP, intensity, and CR all influenced a female's choice of a CS, and thus the male producing it. However, our results indicate that SP was the most important feature influencing the female's choice and that intensity was more effective than CR.Abbreviations CR chirp rate - CS calling song - POD polar orientation diagram - SP syllable period