Survey of fumonisin production by Fusarium species

Fumonisins B1 (FB1) and B2 (FB2), two structurally related mycotoxins with cancer-promoting activity, were recently isolated from corn cultures of Fusarium moniliforme MRC 826. These toxins have been reported to be produced also by isolates of F. proliferatum. Contamination of foods and feeds by F. moniliforme has been associated with human esophageal cancer risk, and FB1 has been shown to be the causative agent of the neurotoxic disease leukoencephalomalacia in horses. Because of the toxicological importance of the fumonisins, the potential to produce FB1 and FB2 was determined in a study of 40 toxic Fusarium isolates representing 27 taxa in 9 of the 12 sections of Fusarium, as well as two recently described species not yet classified into sections. With the exception of one isolate of F. nygamai, fumonisin production was restricted to isolates of F. moniliforme and F. proliferatum, in the section Liseola. The F. nygamai isolate produced 605 micrograms of FB1 g-1 and 530 micrograms of FB2 g-1, and the identity of the toxins was confirmed by capillary gas chromatography-mass spectrometry. This is the first report of the production of the fumonisins by F. nygamai.     

Reproduction ofAmphiporus lactifloreus (Hoplonemertini) on tidal flats: implications for studies on the population biology of nemertines

The reproductive period and life-history parameters were investigated for the hoplonemertineAmphiporus lactifloreus found on the tidal flats of the island of Sylt in the northern Wadden Sea. Every six weeks 20 individuals were collected and then histologically examined to determine the development stage of their reproductive organs.A. lactifloreus reproduces in the late autumn, its peak reproduction being in the second half of November. Individuals from all size classes >20 mm body length produced gametes. Individuals of the cohorts that reproduced in the late autumn of 1992 persisted and grew until July 1993, indicating thatA. lactifloreus is an iteroparous species. The length of relaxed individuals was significantly correlated with their length under anaesthetized conditions, but the regression changed significantly after the reproductive period. Length under ‘relaxed’ conditions was significantly correlated with weight (wet weight, dry weight, and ash-free dry weight); these relationships did not vary significantly before or after the reproductive period. Our results show that important life-history data of intertidal nemertines can be obtained without time-consuming histological studies. On the basis of these findings, recommendations for future studies on the population biology of intertidal nemertines are given. Regular length measurements of nemertines under ‘relaxed’ conditions are proposed as a useful tool for tracking the growth and survival of annual cohorts of intertidal nemertines.     

The SARS‐unique domain (SUD) of SARS‐CoV and SARS‐CoV‐2 interacts with human Paip1 to enhance viral RNA translation

The ongoing outbreak of severe acute respiratory syndrome (SARS) coronavirus 2 (SARS‐CoV‐2) demonstrates the continuous threat of emerging coronaviruses (CoVs) to public health. SARS‐CoV‐2 and SARS‐CoV share an otherwise non‐conserved part of non‐structural protein 3 (Nsp3), therefore named as “SARS‐unique domain” (SUD). We previously found a yeast‐2‐hybrid screen interaction of the SARS‐CoV SUD with human poly(A)‐binding protein (PABP)‐interacting protein 1 (Paip1), a stimulator of protein translation. Here, we validate SARS‐CoV SUD:Paip1 interaction by size‐exclusion chromatography, split‐yellow fluorescent protein, and co‐immunoprecipitation assays, and confirm such interaction also between the corresponding domain of SARS‐CoV‐2 and Paip1. The three‐dimensional structure of the N‐terminal domain of SARS‐CoV SUD (“macrodomain II”, Mac2) in complex with the middle domain of Paip1, determined by X‐ray crystallography and small‐angle X‐ray scattering, provides insights into the structural determinants of the complex formation. In cellulo, SUD enhances synthesis of viral but not host proteins via binding to Paip1 in pBAC‐SARS‐CoV replicon‐transfected cells. We propose a possible mechanism for stimulation of viral translation by the SUD of SARS‐CoV and SARS‐CoV‐2.     

Selective host range restriction of goat cells for recombinant murine leukemia virus and feline leukemia virus type A

We isolated a strain of normal goat fibroblasts which was uniquely selective in that it allowed the replication of xenotropic murine leukemia virus but not polytropic recombinant murine leukemia virus. In addition, feline leukemia virus type A replication was severely diminished in these goat cells, whereas feline leukemia virus type B and feline endogenous RD114-CCC viruses replicated efficiently. No other known cells exhibit this pattern of virus growth restriction. These goat cells allow the study of xenotropic murine leukemia virus in mixtures which also contain recombinant murine leukemia virus and may be helpful in eliminating feline leukemia virus type which often coexists in feline sarcoma or leukemia virus mixtures with other feline leukemia virus types.     

In vivo nuclear magnetic resonance studies on the lugworm Arenicola marina. I. Free inorganic phosphate and free adenylmonophosphate concentrations in the body wall and their dependence on hypoxia

The cytoplasmic concentrations of free inorganic phosphate and free AMP in the body wall of the lugworm Arenicola marina were estimated in order to verify their proposed regulatory role in glycogenolysis during anaerobiosis (Kamp 1993). Using in vivo ³¹P nuclear magnetic resonance spectroscopy the concentration of free inorganic phosphate was determined to be 4.7±0.7 mmol·1^-1 (±standard deviation, n=3) varying with season (Juretschke and Kamp 1995). These values were two to three times lower than those measured in perchloric acid extracts. In contrast, values for the phosphagen phosphotaurocyamine assessed biochemically in the extracts and by in vivo nuclear magnetic resonance were very similar. During the transition from normoxia to hypoxia the concentration of free inorganic phosphate increased to the same extent and at the same rate as the concentration of phosphotaurocyamine decreased. A discrepancy was also found for the biochemically determined AMP and ADP concentrations in the extract and those derived from the equilibrium constants of the taurocyamine kinase (ADP_free) and adenylate kinase (AMP_free) reactions. Calculated concentrations of ADP_free and AMP_free in normoxic specimens were about two or even four orders of magnitude lower than the values determined in extracts. During hypoxia the concentrations of AMP and ADP increase moderately when measured biochemically in extracts, while the values for ADP_free and AMP_free rise three- and nine-fold during the first 3 h of hypoxia. Thereafter, the levels stay constant due to a progressive acidosis. If during hypoxia pH_i is stabilized by addition of buffering substances to the incubation medium, both ADP_free and AMP_free rise continuously. The significant changes found for the concentrations of free inorganic phosphate and AMP_free support their assumed regulatory role in glycogenolysis during anaerobiosis, though these AMP_free values seem too low to actually activate glycogen phosphorylase. The strong effect of pH_i on the levels of ADP_free and AMP_free suggest a mechanism by which acidosis prevents a continuing increase of glycogenolysis (ATP-producing pathway) during prolonged anaerobiosis (protective effect of acidosis).Abbreviations ADP _free cytoplasmic adenosine diphosphate - AK adenylate kinase - AMP _free cytoplasmic adenosine monophosphate - CK creatine kinase - GPase glycogen phosphorylase - MW molecular weight - Int P _i integral of P_i-signal - NMR nuclear magnetic resonance - P _i-free cytoplasmic inorganic phosphate - PCA perchlori acid - PFK 6-phosphofructokinase - PME phosphomonoester - PPA phenylphosphonic acid - (P)Tc (phospho)taurocyamine - S _f saturation factor - Sw sea water - TcK taurocyamine kinase - TRA triethanolamine - TRIS tris(hydroxymethyl)aminomethane     

Tumor necrosis factor in human monocyte-mediated antitumor cytotoxicity

The WEHI-164 target cells pretreated with actinomycin D can be employed in a 7-hour 51Cr release assay that exhibits exquisite susceptibility for cytotoxic monocytes without contribution by natural killer cells. The system can be used either to detect cell-mediated monocyte cytotoxicity directly or to measure cytotoxic-factor activity in cell-free supernatants. Analysis of cytotoxic factor demonstrates molecular characteristics similar to tumor necrosis factor (TNF), and polyclonal as well as monoclonal antibodies specific for TNF can readily neutralize the monocyte-generated cytotoxic factor. In the cell-mediated approach, neutralization can be achieved as well, although somewhat higher amounts of antibody are required. Hence, the WEHT-164/actinomycin D system appears to detect monocyte cytotoxicity that is mediated by TNF.