Comparative residual toxicities of pesticides to the predator Agistemus industani (Acari: Stigmaeidae) on citrus in Florida

Residual toxicities of registered and selected experimental pesticides used on citrus against Agistemus industani Gonzalez (Acari: Stigmaeidae) were compared. Pesticides considered highly toxic to A. industani were: abamectin 0.15 EC at 731ml/ha+FC 435-66 petroleum oil at 46.8l/ha, pyridaben 75WP at 469g/ha, ethion 4EC at 7.01l/ha+FC 435-66 petroleum oil at 46.8l/ha, propargite 6.55 EC at 3.51l/ha, chlorfenapyr 2SC at 1.46l/ha applied alone or in combination with FC 435-66 petroleum oil at 46.8l/ha, sulphur 80DF at 16.81kg/ha, dicofol 4EC at 7.01l/ha, fenbutatin oxide 50WP at 2.24kg/ha, benomyl 50WP at 2.24kg/ha, benomyl 50WP at 1.68kg/ha+ferbam 76 GF at 5.60kg/ha, ferbam 76GF at 11.21kg/ha, neem oil 90EC at 46.8l/ha, and copper hydroxide DF (40% metallic copper) at 4.48kg metallic copper/ha+FC 435-66 petroleum oil at 46.8l/ha. Pesticides that were moderately to slightly toxic included: copper sulphate 98% at 4.48kg metallic copper/ha+FC 435-66 petroleum oil at 46.8l/ha, fenbuconazole 2F at 280ml/ha+FC 435-66 petroleum oil at 46.8l/ha, FC 435-66 petroleum oil applied alone at 46.8l/ha or 23.4l/ha, and diflubenzuron 25WP at 1.40kg/ha. Pesticides that were non-toxic included: fenbuconazole 2F at 585ml/ha, malathion 57EC at 5.85l/ha, FC 435-66 petroleum oil at 46.8l/ha, carbaryl 80S at 3.36kg/ha, chlorpyrifos 4EC at 4.68l/ha, and formetanate 92SP at 1.12kg/ha. Understanding the toxic effects of field weathered pesticides against key predacious mite species is important for effective IPM. The results of this study provide a comparison of direct and indirect toxic effects of various pesticides to A. industani under field conditions.     

The ultrastructure of the corpus luteum of the guinea-pig

Summary An electron-microscopic investigation, based on the suggestion that differences seen in progesterone levels under differing hormonal conditions might be reflected in the ultrastructural organisation of the lutein cells of the guinea-pig was undertaken. Comparisons were made between corpora lutea taken from animals during the normal oestrous cycle, pregnancy and lactation, and after hysterectomy or hypophysectomy.The lutein cells from the oestrous cycle corpus luteum appeared to be of two types, light and dark. The former were more numerous. The main difference between them lay in the arrangement of the endoplasmic reticulum. Lutein cells from corpora lutea (with the exception of the old degenerating corpora lutea) all contained well-developed agranular endoplasmic reticulum, little granular endoplasmic reticulum, several electron-dense lipid granules, lysosomal bodies which ranged from small spherical bodies to large autophagic vesicles and mitochondria. The mitochondria were numerous, and in the corpus luteum of pregnancy, they were closely associated with the parallel arrays of granular endoplasmic reticulum.With minor exceptions, the lutein cells of the guinea-pig present a strikingly uniform picture despite their hormonal condition.The manner in which this uniformity of ultrastructure may be related to observed differences in progesterone levels in the corpus luteum of the guinea-pig is discussed.Meat and Livestock Commission (MLC) Scholar.The authors wish to thank Dr. J. S. Perry for doing the surgery involved in this work and for the specimens of corpora lutea of hysterectomy. They are also grateful to him for his helpful discussions and interest throughout.     

Influence of sarmesin on some dopamine-related types of behaviour

Summary The present study was undertaken to investigate the effects of sarmesin, an analogue of [Sar¹] angiotensin II (ANG II) where the tyrosine hydroxyl group in position 4 is methylated, on dopamine (DA)-related paradigms: locomotor and exploratory behaviour as well as apomorphine (3 mg/kg, ip)-induced stereotypy in rats. Sarmesin (0.5 and 1 g, icv) significantly decreased ambulation and rearing movements, and blocked the inhibitory effect of ANG II (0.1 g) on both types of activity. Sarmesin induced biphasic effects on apomorphine-induced stereotypy depending on the dose increase (0.5 and 5 g, icv) and decrease (10 g). Moreover, sarmesin (5 g) blocked the inhibitory effect of ANG II (2 g, icv) on apomorphine stereotypy. Taken together, these results suggest that sarmesin might interact with AT₁ and AT₂ receptor subtypes. The results further confirm the statement for ANG II-DA interaction in brain structures involved in these types of behaviour.     

The linear tetrasaccharide,Galβ1-4GlcNAcβ1-6Galβ1-4GlcNAc,isolated from radiolabeled teratocarcinoma poly-N-acetyllactosaminoglycan resists the action ofE. freundii endo-β-galactosidase

A novel linear tetrasaccharide, Gal1-4GlcNAc1-6Gal1-4GlcNAc, was isolated from partial acid hydrolysates of metabolically labeled poly-N-acetyllactosaminoglycans of murine teratocarcinoma cells. It was characterized by exo-glycosidase sequencing and by mild acid hydrolysis followed by identification of all partial cleavage products. The tetrasaccharide, and likewise labelled GlcNAc1-6Gal1-4GlcNAc, resisted the action of endo--galactosidase (EC 3.2.1.103) fromE. freundii at a concentration of 125 mU/ml, while the isomeric, radioactive teratocarcinoma saccharides Gal1-4GlcNAc1-3Gal1-4GlcNAc and GlcNAc1-3Gal1-4GlcNAc were cleaved in the expected manner.Abbreviations WGA wheat germ agglutinin - BSA bovine serum albumin - [³H]GlcNAc1-4-GlcNAc1-4GlcNAcOL N,N,NN'-triacetylchitotriose reduced with NaB³H₄     

Sulfur amino acid metabolism in the developing rhesus monkey brain: Interrelationship of taurine and glutamate

The relationship of taurine to glutamate, and to other amino acids, has been examined in the occipital lobe of the developing rhesus monkey. During development taurine decreases in concentration (4.96 mol/g in fetus to 1.52 mol/g in adult) while glutamate increases (7.92 mol/g in fetus to 11.26 mol/g in adult). When the concentration of taurine is plotted against that of glutamate in fetal, neonatal and adult animals there is a significant correlation in the fetal (p<0.01) and adult (p<0.01) but not in the neonatal occipital lobe samples. This correlation in both fetal and adult brain is specific for these two amino acids. Subcellular fractionation studies further indicate that this relationship may be of special importance in nerve endings.This paper is dedicated to Dr. Derek Richter on his seventy-fifth birthday.     

γ-Linolenic acid production from Spirulina platensis

Various Spirulina strains were assayed for their productivity of -linolenic acid (Lnn). Spirulina platensis ARM-346 was found to accumulate large amounts of Lnn. Urea as a nitrogen source was found to be most effective giving a yield of 13.5 mg Lnn/g dry cell mass. With increase in temperature the Lnn content was found to increase along with biomass. The optimum temperature for maximum Lnn and biomass production was found to be 35°C. The Lnn content was highest at 0.06% (w/v) NaCl and 0.07% (w/v) K₂HPO₄. Cells cultivated in the orange region of the electromagnetic spectrum as energy source showed a high content of Lnn, and there was less biomass compared to cells grown in red light. When the culture was left in the dark for various times, after 144 h it contained about 26% more Lnn than in conventionally cultivated cells.     

Nucleic acid metabolism in yeast

Summary The three haploid yeast strains T2tmp1-3, T2tmp1-1, and T6tmp1-51 auxotrophic for 5-dTMP differ in their requirement for thymidylate: 72, 16, and 3 g 5-dTMP/ml will restore optimal growth, respectively. Thymidylate low requirement in strain T2tmp1-1 and T6tmp1-51 is termed tlrA and tlrC, respectively. When the growth medium is made 5x10^-4 M for 5-dTMP only strain T6tmp1-51 is severely inhibited in RNA and DNA synthesis. This inhibition is reversible after removal of excessive 5-dTMP. The inhibitory characteristic is in marked contrast to thymineless death due to the lack of 5-dTMP in strain T6tmp1-51 where only DNA synthesis stops while RNA synthesis continues. The inhibitory effect of 5x10^-4 M 5-dTMP is not due to the 5-dTMP auxotrophy but to the thymidylate low requiring character (tlrC) in strain T6tmp1-51. The arrest of RNA and DNA synthesis by high concentrations of exogenous 5-dTMP suggests a regulatory role of either the monoor triphosphate on nucleoside or nucleotide biosynthesis in yeast.     

Benzyl-N-acetyl-α-d-galactosaminide inhibits the sialylation and the secretion of mucins by a mucin secreting HT-29 cell subpopulation

We have analysed the mucins synthesized by the HT-29 MTX cell subpopulation, derived from the HT-29 human colon carcinoma cells through a selective pressure with methotrexate (Lesuffleuret al., 1990,Cancer Res 50: 6334–43), in the presence of benzyl-N-acetyl--galactosaminide (GalNAc-O-benzyl), which is a potential competitive inhibitor of the 1,3-galactosyltransferase that synthesizes the T-antigen. The main observation was a 13-fold decrease in the sialic acid content of mucins after 24 h of exposure to 5mm GalNAc-O-benzyl. This effect was accompanied by an increased reactivity of these mucins to peanut lectin, testifying to the higher amount of T-antigen. The second observation was a decrease in the secretion of the mucins by GalNAc-O-benzyl treated cells. The decrease in mucin sialyation was achieved through thein situ -galactosylation of GalNAc-O-benzyl into Gal1–3GalNAc-O-benzyl, which acts as a competitive substrate of Gal1–3GalNAc 2,3-sialyltransferase, as shown by the intracellular accumulation of NeuAc2–3Gal1–3GalNAc-O-benzyl in treated cells.Abbreviations BSM bovine submaxillary mucin - MTX methotrexate - PBS sodium phosphate 10mm, NaCl 0.15m, pH 7.4 buffer - pNp p-nitrophenol - TBS Tris/HCl 10mm, NaCl 0.15m, pH 7.4 buffer Enzymes: CMP-NeuAc: Gal1–3/4GlcNAc 2,3-sialyltransferase, ST3(N), EC 2.4.99.6; CMP-NeuAc: Gal1–4GlcNAc 2,6-sialyltransferase, ST6(N), EC 2.4.99.1; CMP-NeuAc: Gal1–3GalNAc 2,3-sialyltransferase, ST3(O), EC 2.4.99.4; CMP-NeuAc: R-GalNAc1-O-Ser 2,6-sialyltransferase, ST6(O)-I, EC 2.4.99.3; CMP-NeuAc: NeuAc2–3Gal1–3GalNAc 2,6-sialyltransferase, ST6(O)-II, EC 2.4.99.7; UDP-GlcNAc: Gal1–3GalNAc-R·(GlcNAc to GalNAc) 1,6-N-acetylglucosaminyltransferase, EC 2.4.1.102; UDP-GlcNAc: GalNAc-R 1,3-N-acetylglucosaminyltransferase, EC 2.4.1.147; UDP-Gal: GalNAc-R 1,3-galactosyltransferase, EC 2.4.1.122.     

In vitro comparison of ceftazidime,aztreonam, cefpirome,gentamicin, imipenem,enoxacin, and ticarcillin plus clavulanic acid against 108 strains ofPseudomonas maltophilia

Pseudomonas maltophilia is an uncommon cause of hospital-acquired infection and is resistant to most of the antimicrobial agents used in the treatment of gram-negative infections. Susceptibility of 108 isolates ofP. maltophilia to ceftazidime, aztreonam, defpirome, gentamicin, imipenem, enoxacin, and ticarcillin plus clavulanic acid was determined by an agar dilution method. The isolates were in general resistant to the antibiotics. Imipenem and cefpirome were not active at clinically achievable levels. Of the isolates, 20% were susceptible to 16 g/ml ceftazidime, 53% were susceptible to 4 g/ml enoxacin, 10% were susceptible to 4 g/ml gentamicin, and 25% were susceptible to 64 g/ml ticarcillin plus 2 g/ml clavulanic acid.     

Corticosteroids inhibit the generation of lymphokine-activated killer activity in vitro

Summary In phase-I clinical trials of adoptive immunotherapy using lymphokine-activated killer (LAK) cells plus recombinant interleukin-2 (rIL-2) (Cetus) for the treatment of malignant glioma, we observed that blood mononuclear cells (MNC) from patients dependent on dexamethasone for management of cerebral edema produced substantially less LAK activity as compared to MNC of normal blood donors or glioma patients not receiving steroid therapy. Therefore, we examined the in vitro effects, brought about by therapeutically attainable concentrations of various corticosteroids, on the proliferative response, production of interferon (IFN-), and induction of LAK activity from blood MNC of normal donors. Incubation in media containing rIL-2 (1000 U/ml) with either dexamethasone, hydrocortisone, methylprednisolone, or prednisolone profoundly affected all of these parameters. First, while 0.01 g/ml of either dexamethasone or hydrocortisone caused a slight enhancement of the mitogenic response of lymphocytes to phytohemagglutinin, a dose-dependent decline occurred as concentrations increased to 10 g/ml. The addition of prednisolone and methylprednisolone elicited a dose-dependent inhibition of lymphocyte proliferation over the entire concentration range tested. At 0.1 g/ml or higher, dexamethasone, hydrocortisone, methylprednisolone and prednisolone significantly (P<0.02) inhibited the production of IFN-: respectively 18.9%, 4.4%, 2.2%, and 12.3% of the IFN- produced by MNC in the absence of steroids. All four corticosteroids inhibited the induction of LAK activity. Compared to MNC that had been incubated with 1000 U/ml rIL-2 alone, MNC cultured with rIL-2 and 10 g/ml either dexamethasone or prednisolone demonstrated significantly lower cytotoxicity (P<0.05) for the natural-killer-cell-resistant cell line, Daudi. Culturing MNC with hydrocortisone had a more dramatic result, causing a significant decline (P<0.01) in lytic activity at both 1.0 g/ml and 10 g/ml, while incubation with methylprednisolone produced a significant drop (P<0.02) in LAK-mediated cytotoxicity at 0.1 g/ml as well as 1.0 g/ml and 10 g/ml. When cytotoxicity was expressed as lytic units per million effectors, a dose-response decline in lytic activity was once again apparent, with hydrocortisone, methylprednisolone and prednisolone showing significant inhibition (P<0.05) at both 1.0 g/ml and 10 g/ml and dexamethasone at 10 g/ml (P<0.01). These results indicate that corticosteroids commonly used in the management of cerebral tumors and other malignancies inhibit induction of LAK activity in vitro, and this may explain why it is often difficult to generate LAK activity from blood MNC of patients who are receiving chronic steroid therapy.     

Expression of α and β tropomyosin subunits during early myogenesis in somites and limb buds of chick embryos

Summary The appearance of and subunits of skeletal tropomyosin in early myogenesis was studied histochemically using monoclonal antibody to tropomyosin and affinity-purified polyclonal antibody to tropomyosin. In muscle cells, in both somites and limb buds, the and subunits are simultaneously expressed and first appear in the somites at the 30–36 somites. The relatively greater amount of than tropomyosin found in early myogenesis is thus likely to result from a higher rate of tropomyosin synthesis.     

Genetic mapping of the component chains of Ia antigens

The genes encoding the two polypeptide chains ( and) that comprise the murine Ia antigens were localized within distinct regions of the major histocompatibility complex (MHC). This was accomplished by correlating allelic forms of the and chains with the MHC congenic strains of mice from which they were isolated. Allelic forms of and chains were distinguished by their unique structural markers, such as isoelectric points, amino acid sequences or peptide maps. The results indicate that the structural genes for both the and chains of I-A subregion antigens are located within the K to I-A genetic interval. In contrast, the gene encoding the chain of I-E subregion antigens is located outside of theI-E subregion and within the K to I-B genetic interval. These findings may have important implications for analysis of observations that complementation by twoI-region genes is sometimes required for development of immune responses.     

Cysteine-induced hypoglycemic brain damage: an alternative mechanism to excitotoxicity

Summary. Central neural damage caused by L-cysteine (L-Cys) was first reported more than 30 years ago. Nevertheless, the exact mechanisms of L-Cys-mediated neurotoxicity are still unclear. Preliminary study in mice demonstrated that, following L-Cys injection, animals developed tachypnea, tremor, convulsions, and death in conjunction with documented hypoglycemia. The aim of the present study was to further investigate the mechanism of L-Cys-mediated hypoglycemic effect and neural damage. Neonatal ICR mice (n=6) were injected with L-Cys (0.5–1.5mg/g body weight [BW]), and their blood glucose and insulin levels were determined up to 90min following the injection. Experiments were repeated in chemically (streptozotocin [STZ]) pancreatectomized animals. Brain histology was assessed. Mice injected with L-Cys exhibited dose-dependent neurotoxicity and higher mortality as compared with controls. L-Cys (1.2–1.5mg/g BW) caused severe hypoglycemia (glucose<42mg/dl) (P<0.001). In STZ-treated (diabetic) animals, L-Cys (1.5mg/g BW) increased plasma insulin levels 2.3-fold and decreased serum glucose levels by 50% (P<0.01). Brain histology revealed destruction of as much as 51% of hippocampal neurons in the L-Cys-treated mice but not in the glucose-resuscitated animals. These findings suggest that L-Cys injection can cause pronounced hypoglycemia and central neural damage which is glucose reversible. Since L-Cys is chemically different from the other excitatory amino acids (glutamate and aspartate), L-Cys-mediated neurotoxicity may be connected to its hypoglycemic effect.     

γδ T-cell receptor repertoire in human peripheral blood and thymus

T-cell clones expressing the T-cell receptor (Tcr) were generated from peripheral blood lymphocytes (PBLs) and from a thymus sample. In the panel of ten thymus-derived clones, four Tcr phenotypes [as defined by the reaction of monoclonal antibodies (mAbs) directed against known V and V regions] were identified. All the clones lacked expression of the V3 V region, while seven clones were V1+ . V1 was found in combination with V9 or with undefined VVregions. In addition, two other Tcr phenotypes were identified on these clones: V9⁺ V1^– V3^– and V9^– V1^– V3^– One of the clones expressed CD4 and another was CD8positive. The remaining clones were CD4^– CD8^–. In the panel of 76 PBL-derived, Tcr-bearing clones, five Tcr phenotypes could be identified. In contrast to the thymus-derived clones, 30% of the clones were V3⁺ whereas V1 was expressed by a minority of the clones only. One clone was CD4-positive and approximately 30% of the clones were CD8-positive. Four of the five mAb-defined Tcr phenotypes could be identified on both thymus and PBL-derived T-cell clones. However, biochemical analysis of the Tcrs demonstrates differences in the usage of Ct- and C2-encoded y chains by T cells derived from the thymus and PBLs. The results therefore indicate that, at the clonal level, similarities and differences exist between the Tcr repertoires expressed in the thymus and by PBLs. Furthermore, they indicate that combinatorial Tcr heterogeneity is larger than has so far been described. The receptor diversity, combined with the potential of Tcr+ cells to express CD4 or CD8, indicates that these cells are a heterogeneous population that might mediate a number of immune functions.     

Ovarian development in Culex nigripalpus and its implication for disease transmission

Ovarian development was investigated in wild and colonized Culex nigripalpus Theobald females. Blood-seeking females with morphologically distinct nulliparous, parous and resorbed ovarian follicles (as opposed to females with degenerating follicles) were collected from the field all year, indicating year around gonoactivity. During the cooler months a larger number of females with resorbed follicles were collected from the field than in warmer months. Laboratory experiments showed that resorbed ovarian follicles occurred in sucrose fed females when deprived of a blood meal after emergence. These resorbed ovarian follicles were functional, since most of them began to develop and mature after the females took a blood meal to repletion. Among females fed a partial blood meal, some did not begin ovarian development and, therefore, exhibited gonotrophic dissociation. Females fed partial blood meals had similar patterns of ovarian development, irrespective of temperature at which they were maintained. Implications of occurrence of females with resorbed ovarian follicles and disease transmission are discussed.Supported in part by National Institutes of Health Research Grants No. A1-06587 and RR-07021. A contribution of the Florida Medical Entomology Laboratory, Vero Beach, Florida, Florida Agriculture Experimental Station Journal Series No. 2367     

Male swarms at landmarks and scramble competition polygyny inPolistes gallicus (Hymenoptera: Vespidae)

At the end of summer, males of Polistes gallicusfly in swarms around vertical landmarks and land in clusters on their favorite perches, where they drag their legs and abdomen. Here males occasionally crowd around a perched female; they make no effort to defend an exclusive mating territory but instead attempt to copulate by displacing rivals from the female. In this work we describe this spatial-nuptial system, which entails site fidelity without territoriality, unisexual swarms, common patrol routes, collective sexual approaches, and scramble competition polygyny. Mating success is evaluated in relation to the familiarity with flight paths (routine patrollers versus newcomers), to the type of sexual approach (single males versus in- group males), and, in the laboratory, to the individual activity level.     

NADH is specifically channeled through the mitochondrial porin channel in Saccharomyces cerevisiae

In many kinds of permeabilized cells, the restriction of metabolite diffusion by a mitochondrial porin closed state has been shown to control the respiration rate. However, since in isolated mitochondria the porin appears to be always open, the physiological relevance of a putative regulation via this channel status is now a subject of discussion. In Saccharomyces cerevisiae, in which some of the NADH dehydrogenase active sites are facing the intermembrane space, this regulatory mechanism might play an important role for the regulation of the cytosolic redox status. Using permeabilized spheroplasts from wild-type and porin-deficient mutant, we show that the NADH produced in the cytosol is channeled to the mitochondrial NADH dehydrogenases through a metabolic network involving the porin channel. Thus, the control exerted by the porin (i.e., open or closed state) seems to be determined through its participation or not in organized metabolic networks.     

Microscale analysis of glycosphingolipids by TLC blotting/secondary ion mass spectrometry: a novel blood group A-active glycosphingolipid and changes in glycosphingolipid expression in rat mammary tumour cells with different metastatic potentials

The glycosphingolipid compositions of rat mammary tumour cell lines with different metastatic potentials for the lung [a parental tumour cell line (MTC) and its subclones MTLn2 (a non metastatic subclone) and MTLn3 (a subclone with high metastatic potential to the lung)] were studied using a newly developed TLC blotting/secondary ion mass spectrometry system and crude glycosphingolipids obtained from 0.5–1×10⁷ cells of each cell line. G_M3 and G_M2 were the major components of the MTC cell line, but they were very minor components in the MTLn2 and MTLn3 cell lines, G_Dla being the major ganglioside. HexNAc-fucosyl-G_Mla was found in the MTLn2 cells by the TLC blotting/SIMS method, and the terminal sugar linkage was shown to be a blood group A-type structure by immunostaining. These findings suggest that the ganglioside is a novel type of blood group A-active ganglioside, GalNAc1-3(Fuc1-2)G_Mla. No blood group A-active lipid was present in MTLn3 cells, whereas Hex-G_Mla and neutral glycosphingolipids with more than 5 sugar residues were. Abbreviations: TLC, thin-layer chromatography; HPTLC plate, high performance thin-layer chromatography-plate; PVDF, polyvinylidene difluoride; SIMS, secondary ion mass spectrometry; GC-MS, gas chromatography-mass spectrometry; C16:0, hexadecanoic acid; C18:0, octadecanoic acid; C22:0, docosanoic acid; C24:0, tetracosanoic acid; d18:1, 2-amino-4-octadecene-1,3-diol; Hex, hexose; HexNAc,N-acetylhexosamine; Gal, galactose; Glc, glucose; GalNAc,N-acetylgalactosamine; Lac, lactose; NeuAc,N-acetylneuraminic acid; Cer, ceramide; Glob, globoside; iGlob, isogloboside; GlcCer, glucosylceramide; LacCer, lactosylceramide; Gb₃Cer, Gal1-4Gal1-4Glc1-1Cer; Gb₄Cer (Glob), GalNAc1-3Gal1-4Glc1-1Cer; iGb₃Cer, Gal1-3Gal1-4Glc1-1Cer; iGb₄Cer (iBlob), GalNAc1-3Gal1-4Glc1-1Cer; Ganglio-series gangliosides are named according to Svennerholm [1].     

Modulation of natural killer activity by thymosin alpha 1 and interferon

Summary A single injection of -interferon (-IFN) (30 000 units/mouse), a major biological modifier of natural killer (NK) cytolytic activity, strongly stimulated NK activity in normal mice, as expected, while the same treatment did not statistically alter the NK response in cyclophosphamide (CY)-suppressed animals.We investigated the possibility of thymosin ₁ cooperating with -IFN in boosting NK activity in CY-suppressed animals.The results show that treatment with thymosin ₁ (200 g/kg) for 4 days, followed by a single injection of -IFN 24 h before testing, strongly restored NK activity in CY-suppressed mice. Thymosin ₁ was, moreover, able to accelerate the recovery rate of NK activity in bone marrow reconstituted murine chimeras.Taken together the data support the concept that the synergic effect between thymosin ₁ and -IFN could be the result of effects on differentiation of the NK lineage at different levels.     

Carbohydrate antigen expression in murine embryonic stem cells and embryos. II. Sialylated antigens and glycolipid analysis

Summary A mouse embryonic stem (ES) cell line E14 and early mouse embryos were stained with a panel of 15 monoclonal antibodies recognizing sialylated or potentially sialylated carbohydrate determinants, Sialyl Le-x and sialyl Le-a were detected on the pre-implantation embryo from the 8-cell stage, and sialyl Le-a weakly on undifferentiated ES cells. Changes in cell surface carbohydrates occurred after induction of ES cell differentiation with retinoic acid (RA) and dibutyryl cAMP. Qualitative analysis of the neutral glycolipids of untreated and RA-treated ES cells using high-performance thin-layer chromatography (HPTLC) revealed few differences between the two types of culture. The major gangliosides in both cultures were indicative of an active a ganglioside synthesis pathway. GD₃, a precursor of the b synthesis pathway, previously reported to be characteristic of embryonal carcinoma (EC) cells, was absent. RA-induced differentiation caused a shift in the spectrum to more complex gangliosides. Application of fast atom bombardment mass spectrometry (FAB-MS) to permethylated derivatives of individual bands permitted partial characterization of an unusual sialylated glycolipid and a rare ganglioside with the suggested structure of GalNAc-GD1a.Abbreviations NeuAc N-acetylneuraminic acid - Cer ceramide - CMH monohexosylceramide - CDH lactosylceramide (Gal1-4Glc1-Cer) - CTH ceramide trihexoside (Gal1-4Gal1-4Glc1-Cer) - globoside (GalNAc1-3 Gal1-4Gal1-4Glc1-Cer) - Forssman antigen (GalNAc1-3GalNAc1-3Gal1-4Gal1-4Glc1-Cer) - GM₃ (NeuAc2-3Gal1-4Glc1-Cer) - GD₃ (NeuAc2-8NeuAc2-3Gal1-4Glc1-Cer) - GM1 (Gal1-3GalNAc1-4[NeuAca2-3]Gal1-4Glc1-Cer) - GD1a (NeuAc2-3Gal1-3GalNAc1-4[NeuAc2-3]Gal1-4Glc1-Cer) - GT1b (Neu5Ac2-3Gal1-3GalNAc1-4[Neu5Ac2-8Neu5Ac2-3]Gal1-4Glc1-Cer) The glycolipids are named according to Svennerholm (1963) and the recommendations of the IUPAC-IUB Commission on Biochemical Nomenclature (1978).