Foraging strategies ofDrosophila melanogaster: A chromosomal analysis

Two larval foraging strategies inDrosophila melanogaster were identified, rover and sitter. Rovers traverse a large area while feeding whereas sitters cover a small area. The difference between rovers and sitters was analyzed genetically by chromosomal substitutions between isogenic stocks. Differences in larval locomotor behavior (crawling behavior) can be attributed to the second chromosome, the rover strategy being dominant over the sitter strategy. Differences in feeding rate (shoveling behavior) are affected additively by both the second and third chromosomes. Natural populations ofDrosophila larvae were sampled three times over a 2-month period; rovers and sitters were at constant frequencies in these populations. The two foraging strategies are discussed in the light of resource utilization in environments where food is distributed continuously or discontinuously.     

The role ofγδ T cells in the normal and disordered immune system

Summary A small population of T cells does not express the conventional T cell receptor characterized by the and polypeptide chains (TCR) but instead, two polypeptides termed and (TCR). This alternative receptor is able to recognize antigen. It appears early in T cell ontogeny, but its role in the thymus prior to the availability of TCR remains unclear. In selected sites such as skin or gut TCR predominates in mice which might suggest a role of T cells in the first line of defense against infection, T cells secrete lymphokines and display cytotoxic activity. However, their activation requirements may differ from what is known for T cells since MHC-nonrestricted and also CD4 and CD8 negative T cells have been described. Preferential activation by mycobacterial antigens possibly indicates a special repertoire of the T cells. In various diseases slightly increased numbers of T cells were found, but these preliminary studies have not yet provided evidence for a major pathogenetic role of T cells.List of abbreviations C constant region (immunoglobulin or TCR gene segment) - CD4 cluster of differentiation 4 (mainly on helper cells) - CD8 cluster of differentiation 8 (mainly on cytotoxic cells) - D diversity region (immunoglobulin or TCR gene segment) - DNA desoxyribonucleic acid - IL2 interleukin 2 - J joining region (immunoglobulin or TCR gene segment) - kD kiloDalton - MHC major histocompatibility complex - NK natural killer (cells) - RA rheumatoid arthritis - TCR T cell receptor - V variable region (immunoglobulin or TCR gene segment)     

2 μm plasmid copy number in different yeast strains and repartition of endogenous and 2 μm chimeric plasmids in transformed strains

By using the renaturation kinetics technique we tried to get informations about the maintenance of the 2 m plasmid in yeast cells. For this purpose we determined the 2 m plasmid copy number: in various yeast strains, in a special set of mutants, in cells treated with ethidium bromide and cycloheximide and in different yeast strains obtained by transformation with 2 m chimeric plasmids.According to the strain used the proportion of 2m DNA varied from 1.1% to 3.9%, which corresponds to 24 to 88 2 m molecules per haploid genome. The particular multiresistant mutant, where the frequent loss of oligomycine resistance is correlated with the loss of extractible covalently closed circular DNA, contained 39 2 m copies per haploid genome. In the partial revertant oligomycine sensitive all the 2 m DNA sequences were lost. (Less than 0.1 copy per haploid genome.)Ethidium bromide did not affect the 2 m copy number while cycloheximide induces an increase of 36%.When a strain containing 88 2 m DNA copies per haploid genome is transformed with 2 m chimeric plasmids there is no significative change in the total number of plasmid: 36 copies of endogenous and 44 of chimeric plasmid per haploid genome. When 2 m chimeric plasmids were introduced in our 2 m-less strain despite the stability of the transformants, there is only 8 copies per haploid genome.     

Mechanism of modulation of single sodium channels from skeletal muscle by the β 1-subunit from rat brain

We studied the molecular mechanism of the rat skeletal muscle -subunit (_I) gating kinetics modulation by the brain ₁-subunit by heterologous expression of single sodium channels from _I and ₁ in Xenopus laevis oocytes. Coexpression of ₁ reduced mean open time at –10 mV to 21% when compared to channels expressed by _I alone. Channels formed by _I exerted multiple openings per depolarization, which occurred in bursts, in contrast to the channels formed by the _I/₁ complex that opened in average only once per depolarizing voltage pulse. Macroscopic current decay (mcd), as evidenced by reconstructed open probability vs. time , was greatly accelerated by ₁, closely resembling mcd of sodium currents from native skeletal muscle. Generally was larger for channels expressed from the pure _I subunit.From our single channel data we conclude that ₁ accelerates the inactivation process of the sodium channel complex.     

Enhanced stability of YEp plasmids in lager brewing yeasts is related to lager brewing yeast 2-μm DNA

Summary YEp plasmid stability in the presence of either Saccharomyces cerevisiae laboratory strain 2-m DNA, or lager brewing yeast 2-m DNA in the same genetic background, was compared under non-selective culture conditions. It was found that YEp plasmids were more stably maintained in the presence of lager 2-m DNA under these conditions. By construction of laboratory-lager 2-m DNA hybrid plasmids, an 867 bp StuI fragment of lager 2-m DNA was shown to be responsible for the enhanced stability of the YEp plasmid. Nucleotide substitutions at two sites were found by sequencing this region. It was also confirmed that increasing cell ploidy enhanced YEp stability under non-selective conditions.     

Differential secretion of TNF-α and IFN-γ by human peripheral blood-derived NK subsets and association with functional maturation

Natural killer cells can be separated into three major subsets (free, binder, and killer) based on their ability to bind and kill sensitive target cells. The nonbinder, nonkiller free cells are the most immature and can be activated to become binders and killers. Natural killer (NK) cells synthesize and secrete several cytokines that are intimately involved in NK activation. This study investigated the secretion of tumor necrosis factor-alpha (TNF-) and interferon-gamma (IFN-) by purified NK cells and NK subsets following activation by various stimuli. K562 target cells stimulated secretion of both TNF- and IFN- by both the binder and the killer subsets but not by the free subset. IFN- activated the secretion of IFN- only, whereas IL-2 activated the secretion of both TNF- and IFN- by the binder and killer subsets and secretion was augmented by the addition of K562 to the cultures. Phorbol myristate acetate (PMA) and ionophore stimulated TNF- and IFN- secretion in both the binder and the killer subsets, though IFN- secretion was more pronounced in the binder subset. Activation of TNF- and IFN- secretion was dependent on de novo protein synthesis. Analysis at the single-cell level demonstrated that the binder subset had the highest frequency of cells secreting IFN-. These results demonstrate that both the binder and the killer subsets can be activated to secrete TNF- and IFN-, whereas the free NK subset secretes little or no TNF- and IFN- following activation. These data suggest that the ability of NK cells to secrete TNF- and IFN- following activation correlates with the functional stage of maturation of NK cells.     

Pseudogenes and short repeated sequences in the rice chloroplast genome

Summary The rice chloroplast genome has been derived from a tobacco-like ancestral form by three major inversions. In the rice genome we have found six pseudogenes, trnG, trnI, 3-rps 12a, trnT, trnE and trnfM/G, all located near inversion endpoints, as well as four short repeated sequences. A comparison of rice, wheat and tobacco sequences indicated that similar pseudogenes are present in wheat but not in tobacco, suggesting that the creation of these pseudogenes occurred before the divergence of rice and wheat. The region downstream of rbcL is a variable region and contains rpl23 in rice and wheat and another 3-rps 12b further downstream in rice. This 3-rps 12b shows a higher homology to the functional rps 12 than 3-rps 12a, which suggests that it appeared more recently. The involvement of these pseudogenes in genome inversions and the creation of the pseudogenes and short repeated sequences are discussed.     

Key word: Chromosome

The word chromosome has survived for over 100 years, because it succinctly defines what early cytologists were able to see with the most modern instrument of their time, a light microscope. It was introduced in a review that became widely known and was published almost simultaneously in German, English and French (Waldeyer 1888, 1889, 1890a, 1890b). In the late 19th century, these three languages were in strong competition for international status as the idiom of science. At the same time, Greek was also considered as a candidate for a nationalistically neutral language of science, and it seems more than coincidence that the word ó matches well the coherent Greek terminology used to describe the cell cycle in mitosis as well as meiosis. Emil Heitz (1935) maintained – in the face of reactionary German efforts to replace the term – that in using the ineradicable word chromosome we think last of all that it indicates a body that stains intensely. Significantly, the key word is no longer restricted to eukaryotes, but has been readily adopted by microbial geneticists (Heidelberg et al. 2000) and acknowledged as defining the elementary unit of genomic partition.     

Transformation of Cochliobolus lunatus with pUT 720 changes the steroid hydroxylating ability of the fungus

Summary The filamentous fungus Cochliobolus lunatus, a known 11-hydroxylator of steroids, was transformed to bleomycin resistance using the heterologous plasmid pUT 720. This plasmid contains the Sh ble gene expressed under the control of the Aspergillus nidulans gpd and trpC expression signals. The bleomycin-resistant colonies appeared with a frequency of six per g of DNA. All colonies were real transformants and no abortive growth was observed. In all transformants tested the plasmid molecules became stably integrated into the genome of the host, and one of the plasmid molecules integrated in a site-specific manner. Transformants retained the ability to hydroxylate the steroid ring, but the hydroxy group was inserted at the 15 position.     

Effects of serine protease inhibitor,tame, on IL-1β in LPS-stimulated human monocytes: Relationship between synthesis and release of a 33-kDa precursor and the 17-kDa biologically active species

LPS stimulation of human monocytes in vitro induced release of the 17-kDa mature IL-1 (mIL-1) but did not result in release of precursor IL-1 (pIL-1). In contrast, the presence of a serine protease inhibitor, N-(p-toluene sulfonyl)-L-arginine methyl ester (TAME; 10 mM) for 6 or 18 h was associated with the LPS-stimulated release of the 33-kDa pIL-1 as well. These effects were initially discerned from observations that the fraction of the total IL-1 produced (as detected by ELISA) that was released from monocytes increased in the presence of TAME, and immunoblot assays confirmed that this fraction was predominantly 33-kDa IL-1. A global decrease in monocyte protein synthesis was also observed after prolonged (18-h) exposure to TAME and was associated with a decrease in IL-1 synthesis, predominantly affecting 31-kDa pIL-1, and a dose-dependent inhibition of TNF- production. Parallel examination of lactate dehydrogenase (LDH) release indicated thatpIL-1 release was unrelated to cell lysis. These results demonstrate that TAME-inhibitable serine proteases are probably involved in the production and eventual proteolysis of the 33-kDa pIL-1 in situ but are probably not mechanistically related to either maturation of the IL-1 molecule or signaling of IL-1 release. IL-1 release appears to be dependent on the amount of total IL-1 synthesized. Serine proteolysis may constitute a degradative pathway for excess precursor, which, if interfered with, could result in release of the higher-molecular-weight forms of IL-1.     

Causal dimensions of college students' perceptions of physical symptoms

According to attribution theory, controllability, locus, and stability are important dimensions underlying causal explanations. The extent to which these theoretical dimensions underlie lay explanations for physical symptoms is unclear. Accordingly, in this study, attributes relevant to the lay public were empirically derived using a multidimensional scaling (MDS) procedure. Undergraduates (N=194) provided similarity judgments for 18 potential causes of physical discomfort. The MDS analysis yielded a three-dimensional solution. The first dimension captured the distinction between physical and nonphysical causes. The second dimension distinguished either variable versus stable causes or those that are controllable versus uncontrollable by health care professionals. The third dimension differentiated causes under low versus high personal control. These findings empirically confirm the theoretically proposed dimensions of personal control and stability and suggest the utility of considering the physical/nonphysical and controllability by health care professional distinctions in future work on attributions in the health domain.     

Identification and characterization of four new GCD genes in Saccharomyces cerevisiae

Summary Mutant strains, resistant against the amino acid analogues 5-methyltryptophan, 5-fluorotryptophan and canavanine were isolated, starting with a trp2 leaky auxotrophic strain. Of 10 such strains, only four turned out to be of the general control derepressed (gcd) mutant type. Three other isolates were shown to be defective in the general amino acid permease system, while the remaining three strains displayed low spore viability and were not further investigated. Complementation tests amongst the four new gcd-mutant strains, including strain RH558 gcd2-1 isolated earlier, yielded five complementation groups: GCD2, GCD3, GCD4, GCD5, and GCD6. All mutant strains showed a dual phenotype, which was not separable by wild type backcrosses: constitutive derepression and slow growth. Epistatis of all gcd mutations over gcn1-1, gcn2-1 and gcn3-1 was found with respect to both phenotypes, except for gcd5-1, which was lethal in these combinations. On the other hand gcn4-101 was found to be epistatic over all gcd mutations, but only with respect to the constitutive derepression phenotype, and not to slow growth; again the combination with gcd5-1 was lethal. Mutation gcd2-1 was mapped on chromosome VII, 50 cM from leu1 and 22 cM from ade6. A new model is discussed, in which GCD-genes are involved in the amino acid uptake into the vacuoles.     

Interferon-γ-activated immature macrophages exhibit a highTrypanosoma cruzi infection rate associated with a low production of both nitric oxide and tumor necrosis factor-α

Murine peritoneal macrophages (MPM) can be subdivided into two subpopulations of mature and immature macrophages. In contrast to mature macrophages, immature ones were highly susceptible toTrypanosoma cruzi infection. This high susceptibility was associated with a low production of ₂-macroglobulin. Interferon- (IFN-)-activated immature macrophages also exhibited a higher infection rate than did IFN--activated mature ones. This higher rate of infection was associated with a low production of both nitric oxide (N=O) and tumor necrosis factor-a (TFN-). In contrast, mature MPM showed a lower rate of infection and produced higher levels of N=O and TFN-. Taken together, these results show a clear-cut difference in the course ofT. cruzi infection in relation to the macrophage maturation state.     

High frequency recombination and the expression of genes cloned on chimeric yeast plasmids: Identification of a fragment of 2-μm circle essential for transformation

Summary We have carried out experiments aimed at explaining the observed variations in transformation frequencies when Saccharomyces cerevisiae or Saccharomyces carlbergensis are transformed with chimeric plasmids that contain one of 4 possible EcoRI fragments of the yeast 2-m circle. These plasmids fall into 2 classes when used to transform 2 different yeast his3 auxotrophs, one (strain LL20) harbours indigenous 2-m circle, and the other (strain YF233) is devoid of this plasmid. Hybrid plasmids containing either the 2.4 mega-dalton (mD) R-form EcoRI fragment (pYF88) or the l.4 mD L-form EcoRI fragment (pYF177) of 2-m circle transform either of the two hosts at a high frequency (50,000 colonies per Mg in LL20 and 10,000 colonies per g in YF233). Hybrid plasmids containing the 1.5 mD R-form EcoRI fragment (pYF87) or the 2.5 mD L-form EcoRI fragment (pYF178) of the 2-m circle transform LL20 at a reduced frequency (6,000–16,000 colonies per g) and YF233 at extremely low frequencies (1–5 colonies per g). All plasmids retrieved from strain YF233 that had been transformed with pYF88 or pYF177 were identical to the original transforming plasmid. Of the plasmids retrieved from strain LL20 that had been transformed with pYF87 and pYF178, approximately half had acquired an extra copy of the 2-m circle. Of the plasmids retrieved from strain LL20 that had been transformed with pYF88 and pYF177, an average of only approximately 13% had acquired an extra copy of 2-m circle. Taken together, these observations indicate that the transformation of yeast by a plasmid lacking the ability to replicate (pYF87 and pYF1780) occurs by the recombinational acquisition of 1 copy of the host 2-m circle, which serves to supply the incoming plasmid with missing essential sequences. A comparison of 2-m circle DNA fragments carried by pYF88 and pYF177 indicates that the region of 2-m circle required for high frequency transformation is a 1.2 mD segment that is common to the 2.4 mD R-form and 1.4 ml) L-form EcoRI fragments. This region extends from the EcoRI cut site adjacent to the PstI site, through to the end of the inverted repeat. However, the inverted repeat sequence alone is not sufficient to bestow high frequency transformation of yeast.     

Activation of atrial muscarinic K+ channels by low concentrations ofβγ subunits of rat brain G protein

Effects of G protein subunits from rat brain on cardiac K⁺ channel was examined in single atrial cells of guinea-pig, using patch clamp techniques. We found that 10 pM concentration of rat brain subunits preparation could activate the atrial muscarine receptor-gated K⁺ channel (I_K.ACh). Neither the detergent, CHAPS, used to suspend nor the boiled preparation activated I_K.ACh. Furthermore, preincubation of subunits preparation in Mg²⁺-free solution, which easily inactivated -GTP-S, did not affect -activation of I_K.ACh. We concluded, therefore, that subunits themselves can activate I_K.ACh.Supported by the grants from the Ministry of Education, Culture and Science of Japan and from the Calcium Signal Workshop on Cardiovascular Systems     

Characteristics of c-fos Gene Expression in the Brains of Rats with Different Investigative and Defensive Behaviors

Differences were found in the expression of the c-fos gene in brain structures of rats with active and passive types of behavior in the open field, hole exploration, and step-down tests. The most marked and intense expression of the c-fosgene was seen in passive rats. After electrocutaneous stimulation in the step-down test, these animals showed maximum expression of the c-fos gene in most areas of the cerebral cortex, the amygdala, in olfactory structures, the hypothalamus, and the brainstem. In active rats in the same conditions, expression of the c-fos gene was seen only in the infralimbic cortex and olfactory nuclei. These results, along with existing data on neurological mapping of the c-fos gene, demonstrate a relationship between the level and topography of c-fosexpression, and with typological and, perhaps, individual characteristics of rats.     

Präzisierung der Reizwirkung mittelfrequenter Wechselströme

Zusammenfassung Bei der Mittelfrequenz-Impuls-Reizung ist streng darauf zu achten, daß keine polaritären Reizkomponenten auftreten. Die diesbezügliche Kontrolle wird am besten mit Hilfe des Konvertibilitätstestes vorgenommen, d. h., es darf beim Vertauschen der Zuführungen zu den Reizelektroden weder die Reizschwelle bzw. die Größe des kollektiven Reizerfolges noch dessen Latenzzeit eine signifikante Änderung erfahren. Auf diese Weise wird die Phasenunabhängigkeit des echten Mittelfrequenz-Reizeffektes nachgewiesen.Diesen Anforderungen entsprechen Mittelfrequenz-Impulse, deren Trägerfrequenz über einige wenige Perioden sich aufschaukelt und ebenso wieder abklingt. Demgegenüber sind Mittelfrequenz-Stromstöße mit phasenstarrem Einsatz und Ende nicht unbedingt frei von polaritären Ein- bzw. Ausschalt-effekten, indem sowohl die erste als auch die letzte Trägerperiode einen polaritären Wechselimpuls-Reizeffekt ergeben kann, je nach Phasenlage bezogen auf die wirksame Reizelektrode und Art der Ansprechbarkeit des Reizobjektes (Nerv) auf entsprechend kurze gleitspiegelsymmetrische Wechselimpulse. Für eine echte Mittelfrequenz-Stromstoß-Reizung ist demnach ebenfalls ein Aufschaukeln und Abklingen der Trägerfrequenz über einige wenige Perioden erforderlich.Es besteht ein prinzipieller Unterschied zwischen der echten Mittelfrequenz-Reizung, die phasen -bzw. periodenunabhängig ist und schon früher als apolaritär bezeichnet wurde, und der konventionellen polaritären Reizung, die als polaritäre Komplikation der Mittelfrequenz-Reizung auftreten kann.Diese Präzisierung der Reizwirkung mittelfrequenter Wechselströme wurde angeregt durch zwei im Text erwähnte Publikationen, in denen in keineswegs überzeugender Weise versucht wird, die Mittelfrequenz-Reizung letzten Endes auf das polare Gesetz der Erregung zurückzuführen.

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Summary The particular excitatory action exerted by middle-frequency alternating current can only be revealed if care is taken to eliminate the occurrence of so-called polarity effects. Such effects are produced by the short alternating impulses represented by the first and the last period of a middle-frequency current pulse and are based on the polar law of excitation.In order to prevent such polarity intrusions, it is necessary to increase and decrease the amplitude of the middle-frequency current pulses over a few carrierperiods, or, to use amplitude-modulated middle-frequency impulses of variable shape and duration of envelope.A true middle-frequency excitatory effect is easily demonstrated by resorting to the convertibility test. It will then become evident that stimulation threshold, magnitude as well as latency of response do not change during reversal of the stimulating poles. This means, that no significant phase change of the response with regard to the carrier-frequency occurs when the leads to the stimulating electrodes are commuted, and that, as a result, true middle-frequency effects do not depend upon one particular catelectrotonic variation among the carrier-periods of a middle-frequency current pulse.It can thus be concluded that a fundamental difference exists between true middle-frequency stimulation, which is based on a non-polarity or apolarity principle, and the conventional stimulation of the polar or polarity type.This paper has been written in the hope of dispelling some errors of interpretation (discussed in the text) tending to ascribe the excitatory effects of middle-frequency impulse stimulation to the classical polar law of excitation.

     

Isolation ofEnterobacter aerogenes susceptible to beta-lactam antibiotics despite high level beta-lactamase production

This report describes a patient with nosocomial meningitis from whom four distinct isolates ofEnterobacter aerogenes were recovered over a complicated course of chemotherapy. The initial isolate was susceptible to expanded spectrum -lactams despite constitutive production of high levels of -lactamase. Resistant isolates recovered during antibiotic therapy had lost a 42,000 outer membrane protein. These data suggest that b-lactam susceptibility in the original isolate was due to hyperpermeability mediated by the 42,000 Dalton protein.     

Combination therapy of cyclosporine with steroid inhibits γ-interferon and interleukin-1 gene expression at the level of mRNA synthesisin vivo

The present study examined the effect of cyclosporine (CsA) administered with steroidin vivo on the capacity of peripheral blood mononuclear cells (PBMC) from kidney transplant recipients to generate cytokines and their gene expression at the level of messenger RNA (mRNA). PBMC from CsA-prednisolone (Pred)-treated recipients displayed 66.9% inhibition (54.3±12.4 IU/ml;N=42;P<0.01) of -interferon (-IFN) production compared with normal individuals (134.6±18.6 IU/ml;N=23). Azathioprine (Az)-Pred-treated recipients displayed significantly less inhibition of -IFN generation (96.0±16.1 IU/ml;N=22;P<0.05) than CsA-treated patients. Macrophages (m) from CsA-Pred-treated recipients displayed 60.0% inhibition (5.1±0.7 U/ml;N=20;P<0.01) of interleukin-1 (IL-1) production compared with normal individuals (13.0±2.9 U/ml;N=21). These results were confirmed by the experiments using cDNA probe for -IFN or IL-1 (, ). High levels of -IFN mRNA in phytohemagglutinin (PHA)-stimulated PBMC or IL-1() mRNA in lipopolysaccharide (LPS)-stimulated m were present in normal individuals but not in CsA-treated recipients as judged by hybridization to a cloned human -IFN or IL-1() cDNA probe. These studies demonstrated that combination therapy of CsA with steroid inhibits both -IFN and IL-1 gene expression at the level of mRNA at physiological concentrations.     

Histochemischer Nachweis der β-Glucuronidase (EC 3.2.1.31) und β-Acetylglucosaminidase (EC 3.2.1.30) in der Rattenleber nach Gabe von 1-Naphthyl-Isothiocyanat und D-Galaktosamin-Hydrochlorid

Zusammenfassung In der vorliegenden Arbeit konnte gezeigt werden, daß die histochemisch nachweisbaren Reaktionsprodukte der-Glucuronidase und-Acetylglucosaminidase der Rattenleber nach Gabe von 1-Naphthyl-isothiocyanat und D-Galaktosamin-HCl zunehmen. Die-Glucuronidase ist vorwiegend in den Kupfferschen Sternzellen nachweisbar.

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Summary In this study the authors, for the first time, could demonstrate by histochemical methods that the activities of-glucuronidase and-acetyl glucosaminidase in rat liver increase in animals which are pretreated with 1-naphthyl-isothiocyanate and galactosamine. Best reaction of -glucuronidase was found in Kupffer cells.