Dissolved organic matter from agricultural fields in the irrigation period

The aim of this study was to quantify and characterize the dissolved organic carbon (DOC) of paddy fields and crop fields in Tottori, Japan. Dissolved organic carbon (DOC) and ultraviolet (UV) absorbance was measured for the filtrated water of each samples. DOC concentration and SUVA (specific UV absorbance) of biodegradation analysis samples were determined around 50 days after the incubation. In the Fukui paddy fields, DOC concentration varied seasonally from 1.1 to 10.1 mg.Cl(-1), showing higher concentration in heavy runoff of non-agriculture period in April. However, DOC concentration variation did not always correspond to rainfall. The Obadake paddy fields also showed a similar pattern with Fukui paddy fields. The daily DOC discharge per area in Fukui (up), Fukui (down), Obadake (south), Obadake (north) paddy fields influent from paddy fields were 0.02, 0.0161, 0.0135 and 0.0027 kg.a(-1).day(-1), respectively. These differences resulted from differences in agricultural types and customs of farmers according to paddy fields and fields. Also, SUVA (an indirect means to evaluate humic substances (hydrophobic fraction)) of the studied influent waters from paddy fields were generally lower than the influent waters from crop fields. The non-biodegradable DOC accounted for 50.2-98%, 46.8-85.5% of the total DOC in the paddy fields and crop fields.

Activation of methionine synthase by insulin-like growth factor-1 and dopamine: a target for neurodevelopmental toxins and thimerosal

Methylation events play a critical role in the ability of growth factors to promote normal development. Neurodevelopmental toxins, such as ethanol and heavy metals, interrupt growth factor signaling, raising the possibility that they might exert adverse effects on methylation. We found that insulin-like growth factor-1 (IGF-1)- and dopamine-stimulated methionine synthase (MS) activity and folate-dependent methylation of phospholipids in SH-SY5Y human neuroblastoma cells, via a PI3-kinase- and MAP-kinase-dependent mechanism. The stimulation of this pathway increased DNA methylation, while its inhibition increased methylation-sensitive gene expression. Ethanol potently interfered with IGF-1 activation of MS and blocked its effect on DNA methylation, whereas it did not inhibit the effects of dopamine. Metal ions potently affected IGF-1 and dopamine-stimulated MS activity, as well as folate-dependent phospholipid methylation: Cu(2+) promoted enzyme activity and methylation, while Cu(+), Pb(2+), Hg(2+) and Al(3+) were inhibitory. The ethylmercury-containing preservative thimerosal inhibited both IGF-1- and dopamine-stimulated methylation with an IC(50) of 1 nM and eliminated MS activity. Our findings outline a novel growth factor signaling pathway that regulates MS activity and thereby modulates methylation reactions, including DNA methylation. The potent inhibition of this pathway by ethanol, lead, mercury, aluminum and thimerosal suggests that it may be an important target of neurodevelopmental toxins.

Efficient assembly of an HIV-1/MLV Gag-chimeric virus in murine cells

In human cells infected by HIV type 1 (HIV-1), the viral Gag protein directs the assembly of nascent viral particles at the plasma membrane. In murine cells, HIV-1 Gag fails to reach the plasma membrane and instead forms nonfunctional intracellular aggregates. The viral determinants of this species incompatibility are previously undefined. To address this problem, we replaced a region of HIV-1 Gag known to direct its localization, the matrix (MA) domain, with functionally homologous regions from Moloney murine leukemia virus (MLV), a murine retrovirus. An HIV-1 clone carrying such a chimeric Gag protein, designated murine HIV (MHIV), assembled more efficiently than nonchimeric HIV-1 and restored plasma membrane localization of Gag in murine cells. Increased efficiency of viral assembly in murine cells was observed from MHIV constructs carrying MLV MA in place of HIV-1 MA. Efficient processing of the HIV-1 capsid protein from the chimeric Gag polyprotein and subsequent infectivity of MHIV required the presence of MLV p12 in addition to MLV MA. These findings strongly suggest that the HIV-1 MA domain of HIV-1 Gag is responsible for the assembly defect in mouse cells. Although these MHIV do not recruit native HIV-1 Env efficiently, they are capable of single-round infection when produced by high-efficiency transfection of human 293 cells and provided with an HIV-1 Env lacking its cytoplasmic tail. With further adaptation, this chimeric MHIV approach may provide the basis for creating an infectious mouse model for HIV/AIDS.

Effects of restricted food access on circadian fluctuation of serotonin N-acetyltransferase activities in hereditary microphthalmic rats

The characteristics in diurnal fluctuation of serotonin N-acetyltransferase activity were examined in normal and microphthalmic mutant rats of the Donryu strain under ad lib or restricted feeding conditions. Under a 12:12-h light:dark (12-h LD) cycle with free access to food, normal-sighted rats exhibited typical nocturnal increases in the activity of pineal serotonin N-acetyltransferase, being more than 50-fold higher in the dark period than that in the light period, but hereditary blind rats showed nonperiodic change in the pineal enzyme activity in the average, suggesting that the rhythms in individuals have become free-running, asynchronous. When the subjective night or subjective day of the mutants was discerned by active or inactive in the locomotor activity, the pineal enzyme activities in the mutants increased at the subjective night but depressed at the subjective daytime. When food access was restricted only for 6 h in the light period of the LD cycle, normal rats still showed the nocturnal increases in the pineal enzyme activity, but hereditary blind rats manifested a blunt peak in the activity of the pineal enzyme at eating time in the light period. The results suggest that microphthalmic mutant rats maintain the ability to shift and to synchronize their circadian phases induced by restricted access to food, even if they completely lack their optic nerve and visual input to the circadian clock.

A novel family of retrotransposons in Xenopus with a developmentally regulated expression

SUMMARY

We have obtained a novel family of LTR-retrotransposons in Xenopus laevis, named Xretpos, from cDNA and genomic clones. Its long terminal repeats (LTRs) can be subdivided into U3, R, and U3 to U5 region, and are bounded by 6 bp inverted repeats. Xretpos contains primer binding site and polypurine tract, and multiple copies of Xretpos-related element are present in the genome. A long open reading frame (ORF) encodes the CCHC motif conserved in retroviral gag proteins and leucine zipper motif capable of forming the coiled-coil. However, no amino acid homology to usually conserved retroviral pol gene was revealed. We report that in vitro synthesized Xretpos complementary RNAs are translated to produce a predicted size of protein. We also show that zygotically activated Xretpos transcripts are restricted to ventro-posterior specific regions and induced by UV-irradiation and BMP-4 overexpression in cycloheximide-dependent way. genesis 26:198-207, 2000.

Prophylaxis for respiratory syncytial virus with respiratory syncytial virus-immunoglobulin intravenous among preterm infants of thirty-two weeks gestation and less: reduction in incidence, severity of illness and cost

OBJECTIVE

To determine the impact of respiratory syncytial virus (RSV) prophylaxis among preterm infants of < or =32 weeks gestation by comparing the severity of illness and cost of RSV-related care during the two winter seasons before (1994 to 1995, 1995 to 1996) with the two seasons after initiation of prophylaxis (1996 to 1997, 1997 to 1998).

METHODS

Preterm infants of < or =32 weeks gestation at risk for hospitalization with RSV infection were identified retrospectively from the infants hospitalized in our neonatal units. Infants were included if they (1) were born 6 months before or during four winter seasons (1994 to 1998), (2) were discharged from the neonatal unit and (3) had remained in the university outpatient clinic system during at least the first winter of life. Preterm infants of < or =32 weeks gestation hospitalized with RSV were identified from our RSV database (which includes cost of hospitalization, duration of hospital stay, pediatric intensive care unit stay and intubation). Infants receiving prophylaxis were identified prospectively.

RESULTS

The incidence of hospitalization with RSV was significantly lower among the cohort of infants born after initiation of prophylaxis: 8.7% (17 of 195) vs. 22% (35 of 159), P = 0.00049 by two tailed Fisher's exact test. Among the cohort of infants born after initiation of prophylaxis (n = 195), 100 infants received prophylaxis. The gestational and chronologic ages of the prophylaxis-treated infants were significantly lower than those of the non-prophylaxis-treated infants (n = 95). The prophylaxis-treated infants also were more likely to have bronchopulmonary dysplasia. Only 1 (1%) of the prophylaxis-treated infants required hospitalization for RSV. Comparison of the cohort of infants born before initiation of prophylaxis to the cohort born after initiation of prophylaxis (includes prophylaxis-treated and non-prophylaxis-treated infants) revealed a significant reduction in severity of illness and cost. The length of stay in the cohort born before initiation of prophylaxis was reduced 83.8%: 373.6 days per 100 infants at risk vs. 60.5 (P = 0.00055). The length of stay in the pediatric intensive care unit was reduced 92.7%: 218.2 days per 100 infants at risk vs. 15.9 (P = 0.00029). The duration of intubation was reduced 95.6%: 187.4 days per 100 infants at risk vs. 8.2 (P = 0.00024). The dollars spent for RSV-related care (hospitalizations and prophylaxis) per 100 infants at risk for RSV was reduced 65% in the cohort of infants born after prophylaxis: $670,590 per 100 infants at risk vs. $234,596 (P = 0.00056). This reduction remained significant (64.9%) if the cost of ribavirin (drug and administration fees) was excluded from the cost of hospitalization.

CONCLUSIONS

These data reveal that RSV prophylaxis significantly reduced the incidence of RSV hospitalizations and severity of illness as well as the cost of RSV-related care among these infants.

A novel gene family with a developmentally regulated expression in Xenopus laevis

We have isolated a new maternal gene called 4G2. 4G2 cDNA encodes a predicted protein of 501 amino acids, and its apparent molecular mass of 61 kDa was determined by SDS-PAGE of 4G2 recombinant protein expressed in E. coli or in vitro translated in rabbit reticulocyte lysate. Amino acid analysis of 4G2 revealed the RGD and LDV motif with a potential cell attachment activity. The open reading frames (ORF) also contained a consensus bipartite nuclear localization signal (NLS). There were number of expressed tag sequences (ESTs) from Drosophila, zebrafish, chicken, mouse, and human origin that encode a high degree of identity to the predicted 4G2 protein, thereby suggesting that 4G2 may constitute a novel gene family whose function has not been elucidated. We also present evidence that 4G2 transcript is maternally synthesized in stage IV oocyte, localized to animal hemisphere of egg, and zygotically reactivated in mid-neurula stage.

Effects of restricted food access on diurnal fluctuation of behaviors and biochemical functions in hereditary microphthalmic rats

The characteristics in circadian rhythms of spontaneous locomotor activity, and some metabolic properties were examined in microphthalmic mutant rats of the Donryu strain under ad lib or restricted food access conditions. The growth of microphthalmic rats was retarded compared to that of normal-sighted rats from the same strain. Under a 12:12-h light:dark (LD) cycle with free access to food, normal-sighted rats showed basically nocturnal patterns of the locomotor activity rhythms, but most of microphthalmic rats manifested free-running rhythms and a few of them showed arrhythmic. When food access was restricted only for 6 h in the light period of the LD cycle, the normal and hereditary blind rats generated gradually new patterns of the locomotor activities in which the animals showed to be more active in the light period. Plasma glucose concentration in normal rats showed a peak after food consumption, but microphthalmic mutants exhibited no periodic changes of the glucose levels. Responses of the biochemical parameters of protein and mineral metabolism to restricted food access in the mutants did not differ from those in normal rats. These results suggest that microphthalmic mutant rats show the free-running circadian rhythm of locomotor activity due to a complete lack of their optic nerve and visual input to the circadian clock, but the mutants maintained the ability to shift their circadian phase induced by restricted food access similar to that in control rats, and also that the mutants have almost normal properties of biochemical and physiological functions except for glucose metabolism.

D4 dopamine receptor-mediated phospholipid methylation and its implications for mental illnesses such as schizophrenia

Previous studies have shown D2-like dopamine receptor involvement in the regulation of phospholipid methylation (PLM), while others have documented impaired methionine and folate metabolism in schizophrenia. Utilizing [14C]formate labeling in cultured neuroblastoma cell lines, we now show that D4 dopamine receptors (D4R) mediate the stimulatory effect of dopamine (DA) on PLM. The effect of DA was potently blocked by highly D4R-selective antagonists and stimulated by the D4R-selective agonist CP-226269. DA-stimulated PLM was dependent upon the activity of methionine cycle enzymes, but DA failed to increase PLM in [3H]methionine labeling studies, indicating that a methionine residue in the D4R might be involved in mediating PLM. A direct role for MET313, located on transmembrane helix No. 6 immediately adjacent to phospholipid headgroups, was further suggested from adenosylation, site-directed mutagenesis and GTP-binding results. A comparison of PLM in lymphocytes from schizophrenia patients vs control samples showed a four-fold lower activity in the schizophrenia group. These findings reveal a novel mechanism by which the D4R can regulate membrane composition. Abnormalities in D4R-mediated PLM may be important in psychiatric illnesses such as schizophrenia.

Different signaling pathway between sphingosine-1-phosphate and lysophosphatidic acid in Xenopus oocytes: functional coupling of the sphingosine-1-phosphate receptor to PLC-xbeta in Xenopus oocytes

In Xenopus oocytes, both sphingosine-1-phosphate (S1P) and lysophosphatidic acid (LPA) activate Ca2+-dependent oscillatory Cl- currents by acting through membrane-bound receptors. External application of 50 microM S1P elicited a long-lasting oscillatory current that continued over 30 min from the beginning of oscillation, with 300 nA (n = 11) as a usual maximum peak of current, whereas 1-microM LPA treatment showed only transiently oscillating but more vigorous current responses, with 2,800 nA (n = 18) as a maximum peak amplitude. Both phospholipid-induced Ca2+-dependent Cl- currents were observed in the absence of extracellular Ca2+, were blocked by intracellular injection of the Ca2+ chelator, EGTA, and could not be elicited by treatment with thapsigargin, an inhibitor of endoplasmic reticulum (ER) Ca2+ ATPase. Intracellular Ca2+ release appeared to be from inositol 1,4,5-trisphosphate (IP3)-sensitive Ca2+ store, because Cl- currents were blocked by heparin injection. Pretreatment with the aminosteroid, U-73122, an inhibitor of G protein-mediated phospholipase C (PLC) activation, to oocytes inhibited the current responses evoked both by S1P and LPA. However, when they were injected with 10 ng of antisense oligonucleotide (AS-ODN) against Xenopus phospholipase C (PLC-xbeta), oocytes could not respond to S1P application, whereas they responded normally to LPA, indicating that the S1P signaling pathway goes through PLC-xbeta, whereas LPA signaling goes through another unknown PLC. To determine the types of G proteins involved, we introduced AS-ODNs against four types of G-protein alpha subunits that were identified in Xenopus laevis; G(q)alpha, G11alpha, G0alpha, and G(i1)alpha. Among AS-ODNs against the G alphas tested, AS-G(q)alpha and AS-G(i1)alpha to S1P and AS-G(q)alpha and AS-G11alpha to LPA specifically reduced current responses, respectively, to about 20-30% of controls. These results demonstrate that LPA and S1P, although they have similar structural features, release intracellular Ca2+ from the IP3-sensitive pool, use different components in their signal transduction pathways in Xenopus oocytes.

Identification and expression study of a Xenopus homologue of prenylated SNARE gene

We have utilized the differential display PCR method to isolate transcripts expressed during early embryogenesis of Xenopus laevis. Among many transcripts that have been found to be expressed differentially during the development, one transcript which was expressed predominantly in the unfertilized egg, was isolated as a full-length cDNA and the sequence was determined. This cDNA contained a predicted size of 198 amino acids. A search of the GenBank database revealed that the predicted amino acid sequence of the cDNA is highly homologous-87.8% identical-to the recently identified human protein, HsYKT6, a prenylated vesicle associated-SNARE ((soluble NSF (N-ethylmaleimide-sensitive fusion protein) attachment protein receptor)). Thus we have named the gene as Xsnare1. RT-PCR analysis showed that the Xsnare1 mRNA expressed throughout the oogenesis, in egg and in the early phase of embryogenesis and the level of expression declined after gastrulation. These results suggest that the Xsnare1, a maternally active, putative Xenopus homologue of prenylated v-SNARE, is a developmentally regulatory gene and may be play a role in the process of the early development of Xenopus laevis.

Feeding rhythm and ornithine decarboxylase activity in hereditary microphthalmic rats

The effects of congenital absence of visual input on daily rhythms of feeding behavior and tissue ornithine decarboxylase activity were examined in hereditary blind rats. Food intake of normal and hereditary microphthalmic rats was determined every 3 h over 48 h under a 12 h-12 h light-dark cycle. Normal rats took their daily food mainly during the dark period, with two clear peaks in the evening and morning, but hereditary microphthalmic rats ate continuously, suggesting that the feeding rhythm of the hereditary microphthalmic rats is not entrained by the light-dark cycle due to a lack of their optic nerve. The hepatic and renal ornithine decarboxylase activities in normal rats showed a circadian rhythm with a peak at 2000 hours in the dark period as reported previously. In hereditary blind rats, however, the hepatic and renal enzyme activities were found not to undergo any remarkable diurnal change through the light-dark period. These results mean that the feeding rhythm and hepatic and renal ornithine decarboxylase activity rhythm in hereditary blind rats disappeared.

Diurnal fluctuation in the enzyme activity and the messenger RNA level of pineal serotonin N-acetyltransferase in normal and hereditary microphthalmic rats

The enzyme activity and the messenger RNA level of pineal serotonin N-acetyltransferase were more than 20- and 50-fold higher, respectively, in the dark period than in the light period in normal rats. In hereditary microphthalmic rats, however, the serotonin N-acetyltransferase activity and its mRNA level did not undergo a great diurnal change through the light and dark periods. These results indicate that the diurnal rhythms of the activity and the mRNA level of serotonin N-acetyltransferase are not detected in the pineal gland of hereditary blind rats, suggesting free-running rhythms in individual animals due to desynchronization of their circadian rhythms by a lack of their optic nerve.

L-trans-2,3-pyrrolidine dicarboxylate: characterization of a novel excitotoxin

This study investigated the in vitro and in vivo excitotoxic properties of a novel conformationally constrained analogue of L-glutamate, L-trans-2,3-pyrrolidine dicarboxylate (L-trans-2,3-PDC). When tested for excitotoxic activity in rat cortical cultures, L-trans-2,3-PDC mimicked the action of NMDA in both acute (30 min) and chronic (24 h) exposure paradigms. This neurotoxicity was attenuated by co-addition of MK-801 (10 microM). Microinjections of L-trans-2,3-PDC into the dorsal hippocampus of male rats also induced a selective pattern of pathology indicative of an NMDA receptor excitotoxin. In contrast to the equipotency observed in vitro, 100 nmol of L-trans-2,3-PDC were needed to produce cellular damage comparable to that induced by 25 nmol of NMDA. Consistent with an action at NMDA receptors, L-trans-2,3-PDC-induced damage could be significantly reduced by co-administration of MK-801 (3 mg/kg i.p.), but not by NBQX (25 nmol). In radioligand binding assays L-trans-2,3-PDC inhibited the binding of 3H-L-glutamate to NMDA receptors (IC50 1 microM), although it also exhibited some cross reactivity with KA and AMPA receptors. L-trans-2,3-PDC was also identified as a competitive inhibitor (Ki = 33 microM) of 3H-D-aspartate uptake into rat forebrain synaptosomes. In contrast to the action of a transported substrate, such as L-glutamate, L-trans-2,3-PDC did not exchange with 3H-D-aspartate that had been previously loaded into the synaptosomes.

In situ hybridization studies of cytomegalovirus and Epstein-Barr virus in reactive histiocytic hyperplasia with hemophagocytosis

We studied 14 adult patients presenting with fever and cytopenia of the peripheral blood and histiocytic hyperplasia with hemophagocytosis (HHH) in the bone marrow regarding an association of cytomegalovirus (CMV) and Epstein-Barr virus (EBV) by using in situ hybridization (ISH) and also evaluated the clinical and laboratory findings according to the encountered organisms. ISH using a CMV RNA probe demonstrated infected cells in 6 out of 14 cases (43%), and ISH using an EBV EBER RNA probe demonstrated infected nuclei in 5 out of the same 14 cases (36%) of HHH. No cases showed a positive reaction with both probes. Three cases showed a negative reaction with both probes. The mean age of all patients was 29 years; and that of the CMV-positive patients was 27 years and that of the EBV-positive patients was 36 years. Organomegaly was found in 3 out of 6 CMV-positive patients (1 hepatomegaly, 1 splenomegaly, 1 hepatosplenomegaly), and 4 out of 5 EBV-positive patients (lymphadenopathy in all 4 cases, hepatosplenomegaly in 2 cases). One of the CMV-positive case had acute myeloblastic leukemia, and 2 EBV-positive cases had underlying malignancy (1 Hodgkin's disease, 1 non-Hodgkin's lymphoma). Seven out of the 14 HHH cases (50%) died within several months after diagnosis. Nucleic acid hybridization methods can be used for the routine examination of the association of CMV or EBV.

Quantifying chromosome changes and lineage involvement in myelodysplastic syndrome (MDS) using fluorescent in situ hybridization (FISH)

A simplified technique for fluorescent in situ hybridization (FISH) was used to investigate the prevalence of chromosomally abnormal clones in 13 cases of myelodysplastic syndrome (MDS). Biotinylated centromeric probes for chromosomes 7, 8, 12 and X, as well as painting probes for chromosomes 7 and 11, were applied to air-dried bone marrow smears stored from 6 to 23 months. Nine of the cases had been previously karyotyped, and five of these demonstrated normal karyotypes which were confirmed by FISH. The remaining four cases showed different chromosome changes. One case of sideroblastic anemia with chronic lymphocytic leukemia showed minor clones with either monosomy 12 (12% of cells) or tetraploidy (15% of cells) by FISH, whereas metaphase cytogenetics had demonstrated trisomy 12 in 20% of cells, with no evidence of tetraploidy. Another case which had been previously karyotyped was found to have a t(7;11) in 90% of cells while only 10% of cells were shown by FISH to contain this translocation. Monosomy 7 was demonstrated by FISH in a case of refractory anemia (RA), while trisomy 8 was found in a case of RA with excess blasts in transformation (RAEB-T), and in both of these cases the aneuploid clone was present in eosinophils as well as in erythroid and granulocytic precursors but not in lymphocytes or histiocytes, thereby demonstrating the value of FISH for identifying the affected cell lineage.