Moniliformin,deoxynivalenol, 3Acetyldeoxynivalenol and zearalenone — Mycotoxins associated with corn cob fusariosis in Poland

An isolated rat liver was perfused with deoxynivalenol (DON) at a dose of 3 mg in a recirculating perfusion system. To identify glucuronide conjugates equal amounts of bile samples, perfusate and liver homogenates were incubated with and without (control) a β-glucuronidase preparation and analyzed by thin layer chromatography and capillary gas liquid chromatography — chemical ionization mass spectrometry. A total of 40.4% of the administered dose of DON was found to be conjugated with glucuronic acid (perfusate 20.4%, bile 19.2%, liver 0.8%), while only 1.3% of the parent DON (perfusate 1.1%, bile 0.2%) was detected. The cleavage of DON-glucuronide was demonstrated by incubating DON-glucuronide containing bile samples with intestine contents under anaerobic conditions.     

Characterization of L-glutamic acid60-L-alanine30-L-tyrosine10-specific suppressor T cells in responder mice restricted by Igh-C-linked genes

A Ts cell subset has been identified in the spleens of responder mice 3 to 6 wk after immunization with an optimally immunogenic dose of L-glutamic acid60-L-alanine30-L-tyrosine10 (GAT). These Ts were positively selected by panning procedures by using a mAb (1248 A4.10) produced by immunization of rats with semipurified mouse GAT-specific, single polypeptide chain suppressor factor. These Ts cells inhibited the activity of virgin Th cells but not memory Th cells and this activity was genetically restricted by genes which are linked to the Ig H chain (Igh) locus on chromosome 12. Use of the Igh recombination strain, BAB.14, which has a crossover near the VHCH region junction, demonstrated that the genes regulating the Igh restriction map telomeric to the VH genes. The Igh-linked restriction regulated the interaction of A4.10+ Ts cells with virgin T cells and not B cells. However, A4.10+ Ts did not act directly on Lyt-2-Th cells, but required the presence of Lyt-2+ cells for suppression. Suppression by GAT-primed A4.10+-Ts cells also required syngenicity at Igh-linked genes by both Lyt-2- and Lyt-2+ T cells. These results indicated that A4.10+-Ts cells were inducer Ts cells which activated Lyt-2+ effector Ts cells which prevented primary GAT specific Th cell activity. The interaction between A4.10+-Ts inducer and effector Ts cells and/or the interaction of the effector Ts and its target cell were restricted by genes linked to the Igh constant region.     

Morphology and Taxonomy of <Emphasis Type="Italic">Apristurus longicephahis</Emphasis> (Lamniformes,Seyliorhinidae)

Data on the individual variation and changes with growth in proportions and morphology are presented for the poorly known Apristurus longicephalus, and compared with those of other species. A. longicephalus is concluded to be a distinct species without synonyms, characterized by its long snout, widely separate nostrils, long caudal fin, short abdomen, very sparse teeth, and low number of monospondylous vertebrae. It is a species of small size, maturing at about 42 cm in total length.     

Scale Growth and Squamation Chronology for the Laboratory-Reared Hermaphroditic Fish <Emphasis Type="Italic">Rivulus marmoratus</Emphasis> (Cyprinodontidae)

Scale morphology, growth and the squarnation chronology are described for the hermaphroditic fish Rivulus marmoratus reared in the laboratory. The scales are round or oval shaped cycloid type, and their sizes are about 0.3–1.0 mm in diameter. The number of ridges increases more rapidly relative to the body growth of the fish in early stages, but this increase is proportionate to growth subsequently. Three loci of scale development have been identified. The scales first appeared on the center of the parietal region at 8 days after hatching. The second locus of scale formation was on the lateral line of the posterior end of the caudal peduncle. A third locus was later observed on the lower right corner of the operculum: The final squamation was completed at 6 weeks after hatching.     

Cultural characteristics and zearalenone production by strains of<Emphasis Type="Underline">Fusarium</Emphasis> from wheat

Conidia of the speciesFusarium culmorum /W.G.Sm./ Sacc. andFusarium graminearum Schwabe are characterized by variability in zearalenone production and dimensions depending on the substrate. The sporulation of isolates from some wheat eultivars have been deprived in vivo and in vitro in the first passage, but not their pathogenicity and toxic metabolites production. Nonsporulating strains produced lower quantités of zearalenone than sporulating ones. Liquid filtrates of such nonsporulating strains had a high phytotoxic effect on wheat caryopses. The crystalline toxin DAS /0,25 ug/ml/ had low phytotoxic effect on wheat caryopses.     

Cumulation of mycotoxins in maize cobs infected with<Emphasis Type="Italic">Fusarium gramihearum</Emphasis>

Maize cobs withFusarium ear rot were collected at 1986 season and five infected byFusarium graminearum were analyzed for presence of triohothecenes and zearalenone. Collected material was subsampled forFusarium damaged kernels and corresponding axial stems and healthy looking kernels. All investigated cobs contained deoxynivalenol (DON) (range 18.0–131.5 mg/kg) and zearalenone (ZEA) (range 0.38–2.17 mg/kg), in four cobs 15-acetyl-deoxynivalenol (15-AcDON) (range 5.2–6.2 mg/kg) was present and two cobs besides three all metabolites contained 3-acetyl-deoxynivalenol (3-AcD0N) (range 0.5–0.8 mg/kg).The average of individual toxins amount in axial stems: in mg/kg was equal to: DON — 110.36, ZEA — 4.57, 15-AcD0N — 16.66, and 3-AcD0N — 1.32.Fusarium damaged kernels contained in average the following amount (mg/kg) of: DON 77.00, ZEA 0.98, 15-AcD0N 3.78 and 3-AcD0N 0.06. Healthy looking kernels contained DON 1.96 mg/kg and ZEA 0.07 mg/kg only. Cooccurrence of 3-AcDON and 15-AcDON in two samples was an interesting finding. The amount of DON in total cob was highly correlated (r = 0.94) with percentage ofFusarium damaged kernels in given ear.     

Amiloride and amiloride analogs inhibit Na+/K+-transporting ATPase and Na+-coupled alanine transport in rat hepatocytes

Amiloride, a commonly used inhibitor of Na+-H+ exchange, has been shown to exhibit a variety of nonspecific effects. Recently, the more potent amiloride analogs, 5-(N,N-dimethyl)amiloride hydrochloride (DMA) and 5-(N-ethyl-N-isopropyl)amiloride (EIA), have been used to control for the nonspecific effects of the parent compound. In the present study, we have explored the effects of these analogs on Na+/K+-transporting ATPase (Na+/K+-ATPase) and Na+-coupled alanine transport in primary rat hepatocyte cultures and rat liver plasma membranes, and we have compared the effects of these analogs with the effects of amiloride and ouabain. Amiloride, DMA, and EIA increased steady-state Na+ content and inhibited ouabain-sensitive 86Rb+ uptake in a reversible, concentration-dependent, ouabain-like manner, with estimated 50% inhibitory concentrations (IC50) of 3.0.10(-3) M, 5.2.10(-4) M, and 1.2.10(-4) M, respectively. Amiloride, DMA and EIA also inhibited ouabain-sensitive ATP hydrolysis in rat liver plasma membranes with similar potency (IC50 values of 2.2.10(-3) M, 2.2.10(-3) M, and 1.7.10(-4) M, respectively). In separate experiments, amiloride (5.10(-3) M), DMA (10(-3) M), and EIA (2.5.10(-4) M) decreased the uptake into hepatocytes of alanine by 20%, 61%, and 59%, respectively, and further studies with DMA (10(-3) M) demonstrated that this inhibition was largely due to a decrease in the Na+-dependent fraction of alanine uptake. These findings indicate that amiloride, DMA, and EIA inhibit hepatic Na+/K+-ATPase directly, reversibly, and with a relative rank order potency of EIA greater than DMA greater than amiloride. All three compounds also inhibit the hepatic uptake of alanine, and presumably could indirectly inhibit other Na+-coupled transport processes as well.     

Elongation factor Tu localized on the exterior surface of the small ribosomal subunit

Protein synthesis elongation factor Tu has been mapped on the surface of the ribosome by immunoelectron microscopy. The EF-Tu binding site is located near the concave portion of the small subunit at the level of the neck and extends 60 to 70 A above and below the neck. The binding site is present on the side of the subunit opposite the platform, i.e. on the exterior subunit surface. This EF-Tu site differs from that found for elongation factor G in that the EF-Tu site is significantly more exposed to the cytoplasm.     

Elongation factor Tu ternary complex binds to small ribosomal subunits in a functionally active state

A complex between elongation factor Tu (EF-Tu), GTP, phenylalanyl-tRNA (Phe-tRNA), oligo(uridylic acid) [oligo(U)], and the 30S ribosomal subunit of Escherichia coli has been formed and isolated. Binding of the EF-Tu complex appears to be at the functionally active 30S site, by all biochemical criteria that were examined. The complex can be isolated with 0.25-0.5 copy of EF-Tu bound per ribosome. The binding is dependent upon the presence of both the aminoacyl-tRNA and the cognate messenger RNA. Addition of 50S subunits to the preformed 30S-EF-Tu-GTP-Phe-tRNA-oligo(U) complex ("30S-EF-Tu complex") causes a rapid hydrolysis of GTP. This hydrolysis is coordinated with the formation of 70S ribosomes and the release of EF-Tu. Both the release of EF-Tu and the hydrolysis of GTP are stoichiometric with the amount of added 50S subunits. 70S ribosomes, in contrast to 50S subunits, neither release EF-Tu nor rapidly hydrolyze GTP when added to the 30S-EF-Tu complexes. The inability of 70S ribosomes to react with the 30S-EF-Tu complex argues that the 30S-EF-Tu complex does not dissociate prior to reaction with the 50S subunit. The requirements of the 30S reaction for Phe-tRNA and oligo(U) and the consequences of the addition of 50S subunits resemble the reaction of EF-Tu with 70S ribosomes, although EF-Tu binding to isolated 30S subunits does not occur during the elongation microcycle. This suggests that the EF-Tu ternary complex binds to isolated 30S subunits at the same 30S site that is occupied during ternary complex interaction with the 70S ribosome.(ABSTRACT TRUNCATED AT 250 WORDS)     

Quantification of the X- and Y-chromosome-bearing spermatozoa of domestic animals by flow cytometry

The relative content of DNA in spermatozoa presumed to be the X- and Y-chromosome-bearing gametes from bulls, boars, rams and rabbits and the amount of DNA in spermatozoa of cockerels was determined by flow cytometry. Differences in the relative content of DNA and proportions of the presumed X- and Y-sperm populations in cryopreserved semen from Holstein, Jersey, Angus, Hereford and Brahman bulls were also determined. Spermatozoa were washed by centrifugation using a series of dimethyl sulfoxide solutions made in isotonic sodium citrate, fixed in ethanol, treated with papain and dithioerythritol to loosen the chromatin structure and remove cellular organelles, and stained quantitatively for DNA with the fluorochrome 4'-6-diamidino-2-phenylindole (DAPI). Approximately 5000 stained sperm nuclei, which were nonviable due to the removal of other cellular organelles during the washing procedure, were measured for DNA in an epi-illumination flow cytometer. A single distinct peak for cockerel spermatozoa and two symmetrical, overlapping peaks for species with X- and Y-spermatozoa were seen. This and other evidence strongly supports the interpretation that the peaks represent the X- and Y-sperm populations. The content of DNA in sperm nuclei from cockerels, bulls, boars, rams and rabbits, as determined by fluorescence flow cytometry, corresponded to biochemical estimates of DNA per sperm cell. Analyses of the bimodal histograms by computer-fitting two Gaussian distributions to the data showed the means of the peaks differed by 3.9, 3.7, 4.1 and 3.9% for bulls, boars, rams and rabbits, respectively. In four replicate analyses of semen from 25 bulls representing 5 breeds, the average population of sperm nuclei in the Y-peaks ranged from 49.5 to 50.5% for all breeds. The X-Y peak differences did not vary within each breed, but were significantly different when the breeds were compared. Spermatozoa from Jersey bulls had larger X-Y peak differences (P less than 0.001) than spermatozoa from Holstein, Hereford, and Angus bulls; spermatozoa from Brahman bulls had smaller X-Y differences (P less than 0.004). It is suggested from the evidence obtained in these studies that flow cytometry can be used to assess the proportion of X- and Y-spermatozoa in semen of domestic animals and is thereby applicable to verification of the effectiveness of enrichment techniques for X- or Y-spermatozoa.