Tumor necrosis factor-alpha triggers antitoxoplasmal activity of IFN-gamma primed macrophages

IFN-gamma is an important mediator of cellular resistance against microbial pathogens and tumor cells due in part to its potent capacity to activate macrophages for enhanced cytotoxicity. The present study demonstrates that TNF-alpha regulates the expression of enhanced antimicrobial activity by triggering IFN-gamma primed macrophages to kill or inhibit intracellular Toxoplasma gondii. Resident mouse macrophages stimulated with rIFN-gamma at levels up to 2500 U/ml failed to display enhanced antitoxoplasmal activity when cultured in vitro under low endotoxin conditions (less than 10 pg/ml), but were triggered by addition of small amounts of LPS (0.1 ng/ml). A similar requirement for LPS as a second signal necessary to trigger antitoxoplasmal activity was observed when IFN-gamma was administered to mice in vivo. The essential nature of this triggering step allowed us to explore the role of cytokines that act as endogenous regulators of macrophage activation. rTNF-alpha, although unable to confer antitoxoplasmal activity when used alone to treat macrophages, was capable of triggering IFN-gamma-primed macrophages cultured under low endotoxin conditions. The ability of TNF-alpha to trigger IFN-gamma-primed macrophages was blocked by rabbit anti-TNF-alpha polyclonal antisera but was not affected by polymyxin B indicating that TNF-alpha triggering was not due to contamination with LPS. Collectively, these findings demonstrate that TNF-alpha performs an important regulatory role in the expression of enhanced anti-microbial activity by IFN-gamma-primed macrophages.     

Tryptase TL2 in the membrane of human T4+ lymphocytes is a novel binding protein of the V3 domain of HIV-1 envelope glycoprotein gp 120.

A novel membrane-bound serine esterase in cultured human T4+ lymphocytes, recently purified and named tryptase TL2, binds specifically to the external envelope protein gp 120 of HIV-1, interacting with its V3 domain. This binding was selectively blocked by inhibitors of tryptase TL2 with a GPCR sequence in their reactive site, synthetic peptides corresponding with the sequences of the V3 domains of various HIV-1 strains with the GPGR sequence, and antibody against tryptase TL2, or neutralizing antibody against the V3 domain of HTLV-IIIB. These findings suggest that tryptase TL2 is a binding protein of the V3 domain of HIV-1 envelope glycoprotein.     

Immunocytochemical localization of cathepsins B,H, and L in the rat gastro-duodenal mucosa

Summary Cathepsins B, H, and L are representative cysteine proteinases in lysosomes of a large variety of cells. Previous immunochemical studies indicated the presence of these enzymes also in the gastrointestinal wall. Using specific antisera, the cellular and subcellular distribution of cathepsins B, H, and L in rat gastric (oxyntic and pyloric part) and duodenal mucosa was investigated by light and electron microscopical immunocytochemistry. The subtypes of cathepsins were distributed differently in the cellular constituents of the epithelia: Cathepsin B was localized to lysosomes of all cells except goblet cells. Cathepsin H was found predominantly in gastric parietal cells (lysosomes) and in secretion granules of pyloric gastrin and duodenal cholecystokinin cells. Cathepsin L immunoreactivities were weak and restricted to a minority of cells (gastric mucous cells, enterocytes). Interstitial cells of the lamina propria immunoreactive for cathepsins H and L were identified as macrophages. The present findings suggest a dual function of cathepsins in the gastro-duodenal mucosa. They (1) cleave enzymatically proteins and peptides ingested in lysosomes, and (2) they may be involved in the processing of biologically active peptides (enteric hormones) from their precursor proteins.     

Bleomycin-induced β-lactamase overexpression in Escherichia coli carrying a bleomycin-resistance gene from Streptomyces verticillus and its application to screen bleomycin analogues

Abstract A bleomycin-resistance gene, designated blmA , has been cloned from bleomycin-producing Streptomyces verticillus by Sugiyama et al. (Gene 151 (1994) 11–16). The present study shows that Escherichia coli harboring the blmA -carrying pUC plasmid overproduced β-lactamase, encoded by an ampicillin-resistance gene on the plasmid, when cultured in the presence of bleomycin, which suggests that bleomycin may act as an inducer (or an activator) for the expression of the specific gene in the presence of blmA . We constructed a vector, designated pMAB50, which senses bleomycin and produces a pigment, using blmA and a Streptomyces tyrosinase gene located under the control of β-lactamase promoter: E. coli harboring pMAB50 produced the melanin pigment in the presence of bleomycin-type antibiotics, suggesting that the transformed E. coli can be employed as a reporter organism to screen bleomycin analogues.     

Intrapopulation genetic variation in the level and rhythm of daily activity in Drosophila immigrans

Genetic diversity within a population, such as polymorphisms and personality, is considered to improve population performance because such intraspecific variations have the potential to alleviate the competition for a limited resource or the risk of predation and sexual harassment at a population level. Variation in the level and rhythm of daily activity in a population could also affect population performance by directly altering ecological, social, and sexual interactions among individuals. However, it remains to be elucidated whether such intra‐population variation in the level and rhythms of daily activity exists in a natural population. Here, we investigated the genetic variation in daily activity within a single natural population of Drosophila immigrans. We established 21 isofemale lines from a single natural population and measured larval activity level and the level and daily pattern of adult activity over a 24 hr period. Larval activity level significantly varied among isofemale lines. Likewise, the activity level in the adult stage significantly varied among lines. The significant variation was also found in the daily pattern of adult activity; some lines showed greater activity level in the daytime, and others showed greater activity level in the night. Our results consistently suggest that there is a genetic variation in behavioral activity in a natural population, probably contributing to shaping the population performance.     

Increased Expression of SLC2A9 Decreases Urate Excretion From the Kidney

Urate is the final metabolite of purine in humans. Renal urate handling is clinically important because under-reabsorption or underexcretion causes hypouricemia or hyperuricemia, respectively. We have identified a urate-anion exchanger, URAT1, localized at the apical side and a voltage-driven urate efflux transporter, URATv1, expressed at the basolateral side of the renal proximal tubules. URAT1 and URATv1 are vital to renal urate reabsorption because the experimental data have illustrated that functional loss of these transporter proteins affords hypouricemia. While mutations affording enhanced function via these transporter proteins on urate handling is unknown, we have constructed kidney-specific transgenic (Tg) mice for URAT1 or URATv1 to investigate this problem. In our study, each transgene was under the control of the mouse URAT1 promoter so that transgene expression was directed to the kidney. Plasma urate concentrations in URAT1 and URATv1 Tg mice were not significantly different from that in wild-type (WT) mice. Urate excretion in URAT1 Tg mice was similar to that in WT mice, while URATv1 Tg mice excreted more urate compared with WT. Our results suggest that hyperfunctioning URATv1 in the kidney can lead to increased urate reabsorption and may contribute to the development of hyperuricemia.     

Time constraints related to sexual maturation and prolonged copulation in the female‐dimorphic damselfly Ischnura senegalensis

Time constraints are critical for reproductive success. To understand the spatiotemporal dynamics of morph frequency in the female‐dimorphic damselfly Ischnura senegalensis, we compared two different morphs for two important time constraints on female reproductive output, i.e. post‐emergence sexual maturation and prolonged copulation. The females of both morphs achieved sexual maturation 4–5 days after emergence, suggesting that the rate of sexual mutation does not result in morph‐specific fitness. The copulation durations declined with the time of onset of copulation in both morphs. Consequently, all copulations terminated at approximately 12:00 hours. Because females show foraging and oviposition activity only after copulation, the copulation duration does not result in morph‐specific time constraints. These two important time constraints do not account for morph‐specific reproductive success and do not affect the evolutionary equilibrium of morph frequency in I. senegalensis.     

Variation in life-history traits of male Japanese fluvial sculpin Cottus pollux in relation to nest abundance along a stream course

Life-history theory predicts the occurrence of variation in the life-history traits of fish populations under different environmental conditions; however, most studies have focused on such variation between geographically separated populations. We compared breeding characteristics and life-history traits of the Japanese fluvial sculpin (Cottus pollux), a bottom-dwelling nest-holding fish, between two adjacent sites sub-divided by a weir along a stream course in central Japan. Males in the area with a lower abundance of nest sites reached sexual maturity at an earlier age and had a shorter life span than males in the area with sufficient nest abundance. Size-dependent male reproduction was found only in areas with a shortage of nest sites, supporting the assumption of competitive exclusion among males for nests. Females matured at the same age in both sites with no differences in age-specific growth rates and mortality. Our results provide evidence for life-history variation in age and size at maturity and age-specific mortality schedule of males in nest-holding fishes in a single stream population via different sexual selection regimes related to differences in nest abundance between sites.     

Body size and temperature dependence of routine metabolic rate and critical oxygen concentration in larvae and juveniles of the round crucian carp Carassius auratus grandoculis Temminck & Schlegel 1846

Routine metabolic rate (RMR, mgO₂ g^?1 h^?1) and critical oxygen concentration (Pc, a hypoxia tolerance indicator, mgO₂ L^?1) were determined in larvae and juveniles of round crucian carp, Carassius auratus grandoculis Temminck & Schlegel 1846, by measuring oxygen consumption at 15°C, 20°C, and 30°C. In addition, the dependence of RMR and Pc on fish body weight (W, g) and temperature (T, °C) was examined to construct minimal mathematical models. RMR depended on W and showed smaller values in larger individuals. RMR was different among the three temperature conditions and showed higher values at higher temperatures. Pc was significantly related to W and was low in larger individuals; that is, larger individuals had a higher hypoxia tolerance. In contrast, Pc was independent of temperature, implying that seasonal temperature fluctuations do not cause seasonal disequilibrium of hypoxia tolerance in round crucian carp. The RMR and Pc models were RMR = 0.0674W^?0.193e^0.0562T and Pc = 1.35W^?0.107, respectively. The metabolic information clarified in this study is essential for habitat quality assessments and aquaculture management of this species.