N., and Bakry, N. M. (2006)

97-4045
English
English
Report
SW 3020 Sources and fate of pollution; SW 2060 Effects on water of human nonwater activities
Water Resources Abstracts
4241305 A1: Alert Info 20030131

Posokhov, Yevgen O. and Ladokhin, Alexey S. (2006). Lifetime fluorescence method for determining membrane topology of proteins. Analytical Biochemistry 348: 87-93.

Chem Codes: Chemical of Concern: DZ Rejection Code: METHODS.

Recently, we introduced a sensitive method for determining the bilayer topology (cis- or trans-leaflet location) of single-site cysteine-linked 7-nitrobenz-2-oxa-1,3-diazol-4-yl (NBD) fluorescent labels on membrane proteins [A.S. Ladokhin, J.M. Isas, H.T. Haigler, S.H. White, Determining the membrane topology of proteins: Insertion pathway of a transmembrane helix of annexin 12, Biochemistry 41 (2002) 13617-13626]. It uses a novel quencher, LysoUB, composed of a single acyl chain attached to a UniBlue chromophore. In its original version, the method relied on the comparison of steady-state fluorescence measurements of membrane-inserted proteins in samples with different distributions of the LysoUB in cis- and trans-leaflets of the lipid bilayer. Here we modify the method to take advantage of the fluorescence lifetime methodology, which allows us to simplify sample manipulation and, as a result, increase the reliability of topology determination. We tested the method using three model systems with artificially created all-cis, all-trans, and isotropic distribution of NBD. Because the quenching efficiency is higher when LysoUB and NBD are in the same leaflet, introduction of the quencher into the cis-leaflet results in a predictably different amount of quenching for these three model systems. Indeed, the addition of 2% LysoUB into the all-cis NBD model system causes strong reduction of the longest lifetime (from 8.1 to 4.9 ns), whereas the same addition of LysoUB results in marginal quenching (from 8.7 to 8.5 ns) in the case of all-trans NBD. This difference provides a good basis for topology determination using time-resolved fluorescence quenching. NBD fluorescence/ FRET/ Membrane proteins/ Site-selective labeling/ Folding/insertion pathway

Posos-Ponce, P., Corrales-Reynaga, J., and Guerrero-Rodriguez, E. (1995). RESPONSE OF WHITE GRUB POPULATIONS TO INSECTICIDES 1991. Burditt, A. K. Jr. (Ed.). Arthropod Management Tests, Vol. 20. Iii+399p. Entomological Society of America: Lanham, Maryland, Usa. Isbn 0-938522-53-1. 0 : 329-330.
Chem Codes: CBF Rejection Code: BOOK ORDERED - BURDITT VOL 2O.

ABSTRACT: BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK CHAPTER ZEA-MAYS CYCLOCEPHALA-COMATA CHLORPYRIFOS DIAZINON FONOFOS ISAZOFOS PROTHIOFOS TERBUFOS CARBOFURAN LINDANE TEFLUTHRIN INSECTICIDE PESTICIDE EVALUATION ARTHROPOD MANAGEMENT TEST LABORATORY BIOASSAY

KEYWORDS: Agronomy-Grain Crops
KEYWORDS: Agronomy-Forage Crops and Fodder
KEYWORDS: Agronomy-Oil Crops
KEYWORDS: Horticulture-Vegetables
KEYWORDS: Pest Control
KEYWORDS: Economic Entomology-Field
KEYWORDS: Economic Entomology-Chemical and Physical Control
KEYWORDS: Gramineae
KEYWORDS: Coleoptera

Posse, E., De Arcuri, B. F., and Morero, R. D. (1994). Lysozyme interactions with phospholipid vesicles: relationships with fusion and release of aqueous content. Biochimica et Biophysica Acta (BBA) - Biomembranes 1193: 101-106.

Chem Codes: Chemical of Concern: DZ Rejection Code: METHODS.

We have previously demonstrated that lysozyme induced fusion of negatively charged phospholipid vesicles and have stressed the importance of electrostatic interactions (Posse, E. et al. (1990) Biochim. Biophys. Acta 1024, 390-394). Using centrifugation and fluorescence polarization techniques, we show, in the present paper that lysozyme interacts with negatively charged liposomes (PC/PA, 9:1), but also with neutral liposomes (pure PC). Moreover, the ionic strength and pH of the media did not modify the protein-liposomes interactions. Such interactions induce the spontaneous release of encapsulated Tb-DPA complex in liposomes. Release and fusion of PC/PA liposomes were observed. As indicated by kinetic studies and substrate curves, fusion and release are two uncoupled processes. Taking these and previous results into account we suggest a hypothetical mechanism where a relationship between aggregation, leakage and fusion of liposomes induced by lysozyme interaction is established. Lysozyme/ Liposome/ Protein-liposome interaction/ Fusion/ Tb-DPA release

Posse, Elena, Lopez Vinals, Alberto, de Arcuri, Beatriz F., Farias, Ricardo N., and Morero, Roberto D. (1990). Lysozyme induced fusion of negatively charged phospholipid vesicles. Biochimica et Biophysica Acta (BBA) - Biomembranes 1024: 390-394.
Chem Codes: Chemical of Concern: DZ Rejection Code: METHODS.

Lysozyme promotes fusion of negatively charged phospholipid vesicles prepared by ethanolic injection. Vesicle fusion was a leaky process as revealed by the release of encapsulated carboxyfluorescein or Tb-DPA complex. Extensive proteolysis of lysozyme inhibited the fusion process. The fusion process was critically dependent on the medium ionic strength; 100 mM of any salt was sufficient to inhibit totally the fusion activity of the protein. The high efficiency of lysozyme (80% RET) was almost constant in the pH range from 4.0 to 9.0, but it was sharply diminished when the pH of the medium was at the isoelectric point of the protein (pI 11.0). Fusion induced by chemically modified lysozyme, showed that the pH profile changed according to the isoelectric point of the protein derivative. These observations stress the importance of electrostatic interactions in the process of fusion induced by lysozyme. Lysozyme/ Vesicle fusion/ Phospholipid

Potter, D. A. (1993). Pesticide and Fertilizer Effects on Beneficial Invertebrates and Consequences for Thatch Degradation and Pest Outbreaks in Turfgrass. In: K.D.Racke and A.R.Leslie (Eds.), ACS Symp.Ser.No.522, Pesticides in Urban Environments: Fate and Significance, 203rd Natl.Meet.of the Am.Chem.Soc., Apr.5-10, 1992, San Francisco, CA 331-343.
Chem Codes: EcoReference No.: 77472
Chemical of Concern: DMB,24DXY,PCZ,DZ,FRM,TDF,CPY,PDM,CTN,BMY,CBL,BDC,EP Rejection Code: FATE/REVIEW.

Prabakaran, S., Tepp, W., and DasGupta, B. R. *. (2001). Botulinum neurotoxin types B and E: purification, limited proteolysis by endoproteinase Glu-C and pepsin, and comparison of their identified cleaved sites relative to the three-dimensional structure of type A neurotoxin. Toxicon [Toxicon]. Vol. 39, no. 10, pp. 1515-1531. Oct 2001.

Chem Codes: Chemical of Concern: DZ Rejection Code: METHODS.

ISSN: 0041-0101

Descriptors: Botulism
Descriptors: Neurotoxins
Descriptors: Botulinum toxin
Descriptors: Proteolysis
Descriptors: Pepsin A
Descriptors: Crystal structure
Descriptors: Glutamyl endopeptidase
Descriptors: Protein folding
Descriptors: Structure-activity relationships
Descriptors: Crystallization
Descriptors: Clostridium botulinum
Abstract: Botulinum neurotoxin (NT) serotypes B and E are approximately 150 kDa proteins. Isolated from the liquid culture of Clostridium botulinum the NT type E is a single chain protein while the NT type B, from the proteolytic strain of the bacteria, is a mixture of dichain (nicked within a disulflde loop located about one-third the way from the N-terminus to the C-terminus) protein and its precursor single-chain protein. Endoproteinase Glu-C (EC 3.4.21.19) and pepsin (EC 3.4.23.1) were used for controlled digestion of NT types B and E; the amino acid residues flanking many of the cleavable peptide bonds were identified and the corresponding proteolytic fragments partially characterized. Chemical identification of 82 and 108 residues of types B and E NT, respectively, revealed that the residue 738 and 1098 in type E NT, identified as Leu and Asn, respectively, differ from those deduced from nucleotide sequences. Several fragments overlapped spanning various segments of the NT's functional domains; they appear to have potential for structure-function studies of the NT. The cleavage sites were compared with the previously determined proteolyzed sites on NT types A and E. The cleavage sites of the NT types A, B and E, all exposed on the protein surface, were scrutinized in the context of the three-dimensional structure of crystallized NT type A (Lacy, D.B., Stevens, R.C., 1999. J. Mol. Biol. 291, 1091-1104]. Detailed procedures for isolation of pure NT types B and E in large quantities (average yield 92 and 62 mg, respectively) suitable for crystallization are reported.
Language: English
English
Publication Type: Journal Article
Classification: J 02822 Biosynthesis and physicochemical properties
Classification: A 01023 Others
Classification: X 24171 Microbial
Subfile: Microbiology Abstracts A: Industrial & Applied Microbiology; Microbiology Abstracts B: Bacteriology; Toxicology Abstracts

Prakash, A. and Bhattacharya, R. (1993). Investigations on Downward Translocation of BPMC in Rice. J.Insect Sci.(Lunhiana) 6: 146-147.

EcoReference No.: 85965

Chemical of Concern: DZ,OXD,FNT,PPHD,CBF; Habitat: AT; Effect Codes: MOR,PHY; Rejection Code: NO CONTROL(ALL CHEMS).

Praly, J. P., El Kharraf, Z., and Descotes, G. (1990). Synthesis of C-1 spirocyclopropyl sugars from anomeric diazides. Tetrahedron Letters 31: 4441-4442.

Chem Codes: Chemical of Concern: DZ Rejection Code: METHODS.

The photolysis of peracetylated glucopyranosylidene diazide in the presence of acrylonitrile in excess yields four C-1 spirocyclopropyl sugars in a 65% combined yield. This unprecedented synthesis of bis C,C-glycosides is supposed to inlvolve anomeric carbene intermediates.

Praly, Jean-Pierre, Di Stefano, Carmela, Descotes, Gerard, and Faure, Rene (1994). Photolysis of sugar anomeric diazides: Sugar-derived tetrazoles as evidences for a major nitrene decomposition pathway. Tetrahedron Letters 35: 89-92.
Chem Codes: Chemical of Concern: DZ Rejection Code: METHODS.

The preponderance of regioisomeric sugar-derived tetrazoles (up to 75% total yield) obtained upon photolysis of protected (benzyl, acetyl) glucopyranosylidene diazides, even in the presence of added acrylonitrile, proved that azidonitrene intermediates predominate over anomeric carbenes, in the reaction. Revisions are presented for its mechanism and one structure.

PRASAD BP, KANTAM ML, CHOUDARY BM, SUKUMAR, K., and SATYANARAYANA, K. (1990). New pesticide metal complexes for controlled release. PESTIC SCI; 28 157-166.
Chem Codes: Chemical of Concern: DZ Rejection Code: METHODS.

BIOSIS COPYRIGHT: BIOL ABS. Six new pesticide metal complexes were synthesised, characterised and evaluated for controlled release by chemical and bioassay methods. Chemical assay and bioassay data demonstrate the increased persistence and increased shelf life of the pesticide upon complexation. Biology/Methods/ Minerals/ Biophysics/Methods/ Herbicides/ Pest Control/ Pesticides/ Arachnida/ Entomology/Economics/ Insecticides/ Pest Control/ Pesticides/ Anatomy, Comparative/ Animal/ Insects/Physiology/ Physiology, Comparative/ Pathology/ Diptera

Prasad, Tekkatte Krishnamurthy, Rangaraj, Nandini, and Rao, Nalam Madhusudhana (2005). Quantitative aspects of endocytic activity in lipid-mediated transfections. FEBS Letters 579: 2635-2642.
Chem Codes: Chemical of Concern: DZ Rejection Code: METHODS.

Variation in transfection efficiency observed in different cell-types is poorly understood. To investigate the influence of endocytic activity on lipid-mediated transfections, we have monitored both the processes in 12 different cell-types. The endocytic activity shows a strong positive correlation (P 70% compared to controls. Our study based on several cell-types demonstrates for the first time that quantitative aspects of endocytosis have decisive influence on the overall process of lipid-mediated transgene expression. Cationic lipid/ Gene delivery/ Endocytosis/ Mitosis

Prieto, A., Molero, D., Gonzalez, G., Buscema, I., Ettiene, G., and Medina, D. (2002). Persistence of Methamidophos, Diazinon, and Malathion in Tomatoes. Bulletin of Environmental Contamination and Toxicology [Bull. Environ. Contam. Toxicol.]. Vol. 69, no. 4, pp. 479-485. 2002.
Chem Codes: Chemical of Concern: DZ Rejection Code: FATE.

ISSN: 0007-4861

Descriptors: Persistence
Descriptors: methamidophos
Descriptors: Malathion
Descriptors: Diazinon
DOI: 10.1007/s00128-002-0087-5
Language: English
Publication Type: Journal Article
Classification: X 24120 Food, additives & contaminants
Subfile: Toxicology Abstracts

Prieto, M. J. E., Castanho, M., Coutinho, A., Ortiz, A., Aranda, F. J., and Gomez-Fernandez, J. C. (1994). Fluorescence study of a derivatized diacylglycerol incorporated in model membranes. Chemistry and Physics of Lipids 69: 75-85.

Chem Codes: Chemical of Concern: DZ Rejection Code: METHODS.

A fluorescence study of a diacylglycerol derivatized with the n-(7-nitrobenz-2-oxa-1,3-diazol-4-yl) chromophore (NBD) was carried out. Fluorescence self-quenching was observed for this probe in lecithin model membranes due to collisional interaction rather than to an aggregational behaviour of the probe. The efficient energy migration (Ro = 28 A) of the NBD fluorophore was studied via the fluorescence depolarization upon increase of probe concentration in membranes, and the results are compared with a model where a random distribution of the probes is assumed. A surface location of the chromophore was concluded for the NBD derivative of diacylglycerol, both from the fluorescence parameters and from the study of its fluorescence quenching by spin label probes. Very high lateral diffusion coefficients were obtained for these probes, both from the self-quenching (D = 2-6 x 10-6 cm2 s-1) and from the spin probe quenching (D = 3.5 x 10-6 cm2 s-1) studies. A concomitant fluorescence study of the related probe NBD-phosphatidylcholine revealed that its photophysical behaviour is similar to the derivatized diacylglycerol. NBD-Dioleoylglycerol/ Phospholipid vesicles/ Fluorescence

PRITCHARD PH (1988). FATE OF POLLUTANTS. J WATER POLLUT CONTROL FED; 60 983-994.
Chem Codes: Chemical of Concern: DZ Rejection Code: FATE.

BIOSIS COPYRIGHT: BIOL ABS. RRM REVIEW WATER POLLUTION KINETICS MONITORING HYDROCARBONS PESTICIDE METALS Ecology/ Oceanography/ Fresh Water/ Biochemistry/ Minerals/ Air Pollution/ Soil Pollutants/ Water Pollution

Proctor, N. H., Moscioni, A. D., and Casida, J. E. (1976). Chicken Embryo Nad Levels Lowered by Teratogenic Organophosphorus and Methylcarbamate Insecticidesag. Biochem.Pharmacol. 25: 757-762.

EcoReference No.: 84915

Chemical of Concern: DZ,CBL,CBF,ADC; Habitat: T; Effect Codes: GRO; Rejection Code: NO ENDPOINT(DZ).

Provini, A., Maio, E. d. i., and Galassi, S. ( Pesticide contamination in some tributaries of the Tyrrhenian Sea. ENVIRONMENTAL POLLUTION AND ITS IMPACT ON LIFE IN THE MEDITERRANEAN REGION., 1991, pp. 157-165, Toxicological and Environmental Chemistry [TOXICOL. ENVIRON. CHEM.], vol. 31-32.

Chem Codes: Chemical of Concern: DMT Rejection Code: SURVEY.

Organophosphorus and organochlorine pesticides were analyzed in some tributaries of the Tyrrhenian Sea, draining an agricultural area of Southern Italy (Calabria). Dimethoate, diazinon and lindane are the pesticides most frequently found in river waters. Occasionally parathion-methyl is present. Results are in good agreement with those expected on the basis of sale data and persistence. Pesticide concentrations in water are generally higher by far than those of the large rivers and similar to levels determined in some other Mediterranean rivers (Spain, Greece). The risk to the aquatic life by these compounds and their contribution to the sea pollution are discussed. Classification: Q5 01503 Characteristics, behavior and fate; P 2000 FRESHWATER POLLUTION agricultural pollution/ pollution effects/ pesticides/ river discharge/ organophosphorus compounds/ organochlorine compounds/ phosphorus compounds/ tributaries/ MED, Italy, Calabria/ freshwater organisms/ chlorine compounds/ MED, Tyrrhenian Sea/ marine pollution/ Italy, Calabria/ Tyrrhenian Sea

Provini, A., Maio, E. d. i., Galassi, S., Lahaniatis, E. S., Parlar, H., Lay, J. P., Pfister, G., Bergheim, W., and Kotzias, D. (eds) (1991). Pesticide contamination in some tributaries of the Tyrrhenian Sea.
Chem Codes: Chemical of Concern: DZ Rejection Code: SURVEY.

ISSN: 0277-2248

Descriptors: agricultural pollution
Descriptors: pollution effects
Descriptors: pesticides
Descriptors: river discharge
Descriptors: phosphorus compounds
Descriptors: tributaries
Descriptors: freshwater organisms
Descriptors: chlorine compounds
Descriptors: marine pollution
Descriptors: organophosphorus compounds
Descriptors: organochlorine compounds
Descriptors: MED, Italy, Calabria
Descriptors: MED, Tyrrhenian Sea
Descriptors: Italy, Calabria
Abstract: Organophosphorus and organochlorine pesticides were analyzed in some tributaries of the Tyrrhenian Sea, draining an agricultural area of Southern Italy (Calabria). Dimethoate, diazinon and lindane are the pesticides most frequently found in river waters. Occasionally parathion-methyl is present. Results are in good agreement with those expected on the basis of sale data and persistence. Pesticide concentrations in water are generally higher by far than those of the large rivers and similar to levels determined in some other Mediterranean rivers (Spain, Greece). The risk to the aquatic life by these compounds and their contribution to the sea pollution are discussed.
Conference: 5. International Congress on Environmental Pollution and its Impact on Life in the Mediterranean Region, Blanes (Spain), 2-6 Oct 1989
Language: English
English
Publication Type: Book Monograph
Publication Type: Conference
Environmental Regime: Marine; Brackish; Freshwater
Classification: Q5 01503 Characteristics, behavior and fate
Classification: P 2000 FRESHWATER POLLUTION
Subfile: Pollution Abstracts; ASFA 3: Aquatic Pollution & Environmental Quality

Prysak, M. F. and Joesten, M. D. (1970). Metal complexes of ethyl dimethylamidopyrophosphates. Inorganica Chimica Acta 4: 383-389.

Chem Codes: Chemical of Concern: DZ Rejection Code: METHODS.

Metal ion complexes of asym-diethyltetramethyldiami- do-pyrophosphate (ASM) and ethl hexamethyltria- midopyrophosphate (MONE) have been prepared. Complexes of tetraethyl pyrophosphate (TEPP) are very difficult to isolate. Thus far, only an adduct of TEPP with antimony pentachloride has been isolated. The coordinating ability of ASYM, MONE, and TEPP is compared with that of octamethylpyrophosphoramide (OMPA) and sym-diethyl tetramethyl- diamidopyrophosphate (SYM). The order of coordinating ability is OMPA>MONE>SYM>ASYM>TEPP.

Puyal, Christophe, Maurin, Luc, Miquel, Genevieve, Bienvenue, Alain, and Philippot, Jean (1994). Design of a short membrane-destabilizing peptide covalently bound to liposomes. Biochimica et Biophysica Acta (BBA) - Biomembranes 1195: 259-266.
Chem Codes: Chemical of Concern: DZ Rejection Code: METHODS.

We characterized the physical and biological properties of a 14-residue amphipathic sequence called SFP (for short fusogenic peptide). At acidic pH, this short synthetic peptide interacts with various phospholipidic monolayers. These interactions were correlated with a pH-dependent conformational transition of SFP resulting in a hydrophobic [alpha]-helical structure. The hemolysis assay showed a pH-dependent weak membrane destabilizing activity of SFP. However, membrane anchoring of SFP through a covalently bound myristic acid enhanced by 1000-fold its membrane-destabilizing power. Moreover, SFP covalently bound to fluorescent-labeled liposomes induced a pH-dependent mixing of both membranes. SFP, a small synthetic peptide, is thus able to mimick many aspects of viral protein-induced membrane fusion: conformational change, membrane destabilization, membrane anchoring and finally pH-dependent lipid mixing. Fusogenic peptide/ Monolayer/ Liposome

Qadri, N. and Dutta, H. M. (1995). Long Term Effects of Low and High Concentrations of Diazinon on Bluegill Fish, Lepomis macrochirus: A Light Microscopic Study. Am.Soc.Zool. 144A.

EcoReference No.: 45078

Chemical of Concern: DZ; Habitat: A; Effect Codes: CEL; Rejection Code: NO ABSTRACT.

QADRI NB and DUTTA HM (1997). EFFECTS OF DIAZINON ON THE GILL AND MACROPHAGE OF THE BLUEGILL SUNFISH LEPOMIS MACROCHIRUS A TEM STUDY. FIFTH INTERNATIONAL CONGRESS OF VERTEBRATE MORPHOLOGY, BRISTOL, ENGLAND, UK, JULY 12-17, 1997. JOURNAL OF MORPHOLOGY; 232 311.

Chem Codes: Chemical of Concern: DZ Rejection Code: ABSTRACT.

BIOSIS COPYRIGHT: BIOL ABS. RRM MEETING ABSTRACT LEPOMIS-MACROCHIRUS BLUEGILL SUNFISH DIAZINON GILLS MACROPHAGE DETOXIFICATION SURVIVAL POLLUTION DEFENSE RESPONSE TOXICOLOGY TRANSMISSION ELECTRON MICROSCOPY RESPIRATORY SYSTEM RESPIRATORY SYSTEM BLOOD AND LYMPHATICS IMMUNE SYSTEM ANALYTICAL METHOD Congresses/ Biology/ Animals/ Cytology/ Histocytochemistry/ Cytology/ Microscopy/ Microscopy, Electron/ Respiratory Tract Diseases/Physiopathology/ Poisoning/ Animals, Laboratory/ Immunity, Cellular/ Fishes

Qadri, S. S. H., Sultana, H., and Anjum, F. (1982). Selective Toxicity of Organophophorous and Carbamate Pesticides to Honey Bee and Freshwater Fish. Int.Pest Control 24: 124-74.

EcoReference No.: 68557

Chemical of Concern: DZ; Habitat: AT; Effect Codes: MOR,BCM; Rejection Code: NO CONTROL(ALL CHEMS).

Qiao, D. a. n., Seidler, F. J., and Slotkin, T. A. *. (2001). Developmental Neurotoxicity of Chlorpyrifos Modeled in Vitro: Comparative Effects of Metabolites and Other Cholinesterase Inhibitors on DNA Synthesis in PC12 and C6 Cells. Environmental Health Perspectives [Environ. Health Perspect.]. Vol. 109, no. 9, pp. 909-913. Sep 2001.

Chem Codes: Chemical of Concern: DZ Rejection Code: IN VITRO.

ISSN: 0091-6765

Descriptors: Chlorpyrifos
Descriptors: Pesticides (organophosphorus)
Descriptors: Neurotoxicity
Descriptors: DNA biosynthesis
Abstract: The widely used organophosphate pesticide chlorpyrifos is a suspected neuroteratogen. In the current study, we compared the effects of chlorpyrifos and its major metabolites in two in vitro models, neuronotypic PC12 cells and gliotypic C6 cells. Chlorpyrifos inhibited DNA synthesis in both cell lines but had a greater effect on gliotypic cells. Chlorpyrifos oxon, the active metabolite that inhibits cholinesterase, also decreased DNA synthesis in PC12 and C6 cells with a preferential effect on the latter. Trichloropyridinol, the major catabolic product of chlorpyrifos, had a much smaller, but nevertheless statistically significant, effect that was equivalent in both cell lines. Diazinon, another organophosphate pesticide, also inhibited DNA synthesis with preference toward C6 cells, but was less effective than was chlorpyrifos. Physostigmine, a non-organophosphate cholinesterase inhibitor, was less effective than either chlorpyrifos or diazinon, but still caused significant inhibition of DNA synthesis in C6 cells. We also found that the addition of sera protected the cells from the adverse effects of chlorpyrifos and that the effect could be reproduced by addition of albumin. These results indicate that chlorpyrifos and other organophosphates such as diazinon have immediate, direct effects on neural cell replication, preferentially for gliotypic cells. In light of the protective effect of serum proteins, the fact that the fetus and newborn possess lower concentrations of these proteins suggests that greater neurotoxic effects may occur at blood levels of chlorpyrifos that are nontoxic to adults.