Cholesterol is not an essential source of nutrition for Mycobacterium tuberculosis during infection

Rv1106c (hsd; 3β-hydroxysteroid dehydrogenase) is required by Mycobacterium tuberculosis for growth on cholesterol as a sole carbon source, whereas Rv3409c is not. Mutation of Rv1106c does not reduce Mycobacterium tuberculosis growth in infected macrophages or guinea pigs. We conclude that cholesterol is not required as a nutritional source during infection.     

Trichonotus halstead, a new sand-diving fish from Papua New Guinea

Synopsis Trichonotus halstead, family Trichonotidae, is described from 3 males and 4 females collected from a sand slope off the northwest end of Normanby Island, Papua New Guinea. It was part of a large population of 4 sympatric species of Trichonotus. The elaborately colored dorsal fin of the male, distinct among trichonotids, is brilliant gold anteriorly followed by a black patch, then a series of 8 to 40 conspicuous, black or dark brown spots that extend onto the upper caudal fin. The spines of the long dorsal fin are filamentous in the male and are numerous (VI to VIII, VII) in both sexes. This species lives in harems (1 male: 4 or 5 females) in well-defined territories and spends more than 80% of its day perched on sand. It feeds on benthic crustaceans and low drifting plankton. When disturbed, it dives into the sand where it also spends the night. It retires within 18 minutes after sunset and emerges within 11 minutes of sunrise. Mating takes place 6:00 h on the sand and the female then picks up the eggs into her mouth. There is evidence of gill-chamber brooding.     

An exploration of instructor perceptions of community college students’ attitudes towards evolution

Background

Faculty perception of student knowledge and acceptance of subject matter affects the choice of what to teach and how to teach it. Accurate assessment of student acceptance of evolution, then, is relevant to how the subject should be taught. To explore the accuracy of such assessment, we compared how community college instructors of life sciences courses perceive students’ attitudes towards evolution with those students’ actual attitudes towards evolution.

Results

The research had two components: (1) a survey of students of several biology classes at a community college about their acceptance of evolutionary theory and (2) interviews with the biology faculty teaching those classes about their perceptions of their students’ attitudes towards evolution. Results of the study indicate relatively high levels of acceptance of evolution among community college students at this West Coast institution. We also found that community college instructors of life sciences courses varied in accuracy of their perceptions of their students’ attitudes towards evolution–but not systematically. Although one professor assessed each class quite accurately, the other two professors frequently underestimated the acceptance of evolution among their students.

Conclusions

Errors in perception seemed independent of whether the class was composed of majors, nonmajors, or a combination. Clearly, in our sample there is much idiosyncrasy regarding community college instructor accuracy concerning student opinions about evolution.

     

Human lymphokine preparations which generate tumoricidal properties of human monocytes in vitro may be distinct from gamma interferon

Summary The purpose of these studies was to determine whether stimulated human lymphocytes produce lymphokines distinct from IFN, that can activate human blood monocytes to lyse tumor cells. We undertook this investigation because of the controversy concerning whether MAF and IFN are the same molecule. Crude lymphokine preparations prepared from normal human mononuclear cells incubated with Con A and rich in MAF activity also contained 1000 U/ml IFN as measured by the virus neutralization assay. However, the induction of tumoridical activity in monocytes by the lymphokine preparation could be dissociated from the IFN activity, based on the following data: (1) Heat treatment (100 °C for 2 min) removed the antiviral activity of the lymphokine yet did not diminish its MAF-like activity when measured in a 72 h cytotoxicity assay against ¹²⁵I IUdR-labeled human A375 melanoma cells. (2) Likewise, treatment of this lymphokine preparation with a twofold excess of anti-IFN antibody neutralized antiviral activity but once again had no effect on its ability to activate monocyte tumoricidal function. In contrast, both heat treatment and anti-IFN antibody abolished monocyte activation by equivalent units of human recombinant IFN. Taken together, these data suggest that there is a molecule(s) distinct from IFN which can activate human monocytes for tumoricidal function. Furthermore, this dissociation of MAF and IFN activity was dependent on the use of a long-term (72 h) assay, since activation of tumoricidal activity in an 18–24 h assay appeared to be attributable solely to IFN.     

Spawning behavior of the collared knifefish, Cymolutes torquatus (Labridae) in Papua New Guinea

A colony of about 10 males and nearly 50 females of Cymolutes torquatus was found living over a sandy substrate on the northwest coast of Normanby Island, Papua New Guinea at depths 14.6 to 18.3 m. Each male appeared to maintain a harem territory, approximately 10 to 14 m², with 4 or 5 females living in sub-units of this territory. Eleven matings of 4 males with 2 to 4 females each were observed on 9 and 10 April 1993. The broadcast spawning of C. torquatus is similar to that of razorfishes in the genus Xyrichtys, but in contrast to most tropical sand-dwelling fishes which mate at dawn or dusk, C. torquatus mated mid-morning between 9:38 to 10:50 h. Sexual dichromatism, color changes during mating, and cleaning of C. torquatus by juvenile Halichoeres zeylonicus are documented with color photographs.     

Anti-(tumor necrosis factor) alters the response of human monocytes to liposomal muramyl tripeptide

The purpose of this study was to examine the mechanisms by which liposome-encapsulated muramyl tripeptide phosphatidylethanolamine (L-MTP-PE) stimulates monocytes to produce tumor necrosis factor (TNF) and interleukin-1 (IL-1). We have previously shown that secretion of TNF protein occurred 2–4 h following incubation of monocytes with L-MTP-PE and that this stimulation of TNF production was associated with an increase in TNF mRNA. Increased intracellular interleukin-1 (IL-1) and IL-1 were not detected until 8 h after exposure to L-MTP-PE. To determine whether TNF played a role in the stimulation of IL-1 production by L-MTP-PE, normal human monocytes were incubated with L-MTP-PE or medium in the presence or absence of anti-TNF or anti IL-1 plus anti IL-1. Enhanced expression of IL-1 and IL-1 mRNA was inhibited at 4 h but not 24 h when monocytes were incubated with L-MTP-PE plus anti-TNF compared with L-MTP-PE alone. By contrast, enhanced expression of TNF mRNA wasnot inhibited at any time when monocytes were incubated with L-MTP-PE and anti-IL-1 plus anti-IL-1. These data indicate that the up-regulation of IL-1 seen in monocytes following L-MTP-PE exposure may be due in part to the production of TNF. The up-regulation of TNF, however, appears to be independent of IL-1 production.     

Effect of ibuprofen on monocyte activation by liposome-encapsulated muramyl tripeptide phosphatidylethanolamine (CGP 19835A): Can ibuprofen reduce fever and chills without compromising immune stimulation?

The purpose of this study was to determine the effects of ibuprofen on the ability of liposome-encapsulated muramyl tripeptide phosphatidylethanolamine (L-MTP-PE) to activate human blood monocytes in vitro. We undertook these experiments because the major toxic side-effects following L-MTP-PE infusion, fever and chills, could be prevented when ibuprofen was given orally immediately before L-MTP-PE infusion. It was therefore important to determine whether ibuprofen interfered with the macrophage-activation properties of L-MTP-PE. Peripheral blood monocytes were isolated from normal donors, then incubated with L-MTP-PE in the presence or absence of ibuprofen. The cytotoxic properties of the monocytes were assessed by a radioisotope-release assay against A375 cells. Ibuprofen at dose levels of 40 µg/ml suppressed the generation of the cytotoxic phenotype but did not interfere with the killing process once the cells were activated. Interleukin-1 (IL-1) and tumor necrosis factor (TNF) production, as well as the mRNA expression of these cytokines, was suppressed by 40 µg/ml ibuprofen. Since IL-1 and TNF play a crucial role in the cytotoxic function of monocytes, these findings may explain the mechanism by which ibuprofen inhibited the generation of the cytotoxic phenotype by L-MTP-PE. By contrast, ibuprofen dose levels up to 10 µg/ml had no effect on the generation of monocyte-mediated cytotoxicity by L-MTP-PE and no effect on the production, secretion, or mRNA expression of TNF and IL-1. Therefore, we concluded that if ibuprofen is to be used to control the side-effects of L-MTP-PE, blood levels of up to 10 µg/ml are desirable. In two of three patients, we determined that an oral dose of 200 mg given immediately before L-MTP-PE infusion could achieve these desired blood levels.