Characterizing zoo-housed Bactrian camel (Camelus bactrianus) reproduction using gonadal steroid metabolite analysis in feces

Millions of people globally depend on camelids, which demands an increased knowledge of their reproduction. We used zoo-housed Bactrian camels (Camelus bactrianus) to better understand camelid reproductive physiology. Our specific objectives were to: 1) validate the use of fecal hormone metabolite analysis to characterize camel reproductive physiology during sexual maturity and pregnancy; and 2) determine the influence of season on male and female reproduction. We collected fecal samples from 1 male and 3 females housed at Lincoln Park Zoo (Chicago, IL, USA) 1 to 2 times per week for 3.5 years. Extracted hormones were analyzed using enzyme immunoassays for progestogen (FPM), estrogen (FEM), and androgen (FAM) metabolite concentrations. One female sexually matured during our study as evidenced by increased FEM baseline. Results demonstrated seasonal effects on male androgen production with FAMs higher (P < 0.05) January to June (mean ± SEM: 664.6 ± 22.6 ng/g wet feces), compared to July to December (401.6 ± 17.5 ng/g wet feces). One female experienced a persistent corpus luteum, a reproductive abnormality, which was identified by prolonged elevated FPM. FPMs increased during pregnancy for two females (452.9 ± 24.9 and 294.4 ± 19.8 ng/g wet feces) with a gestation of 404 d and 442 d, respectively. The third female never conceived. The FEMs varied (P < 0.05) during the year with no clear seasonal patterns (monthly mean range: 213.1-371.0 ng/g wet feces). Fecal hormone metabolite analysis is a validated method for assessing male seasonality and female pregnancy in the Bactrian camel and can for their management and conservation in zoos and the wild.

Project HELP: a study protocol to pilot test a shared decision-making tool about treatment options for patients with hepatitis C and chronic kidney disease

BACKGROUND

Recent advances in treatment have given patients with chronic kidney disease (CKD) access to safer and more effective medications to treat comorbid hepatitis C virus (HCV) infection. Given the variety and complexity of treatment options that depend on patients' clinical characteristics and personal preferences, education and decision support are needed to prepare patients better to discuss treatment options with their clinicians.

METHODS

Drawing on International Patient Decision Aids Standards guidelines, literature reviews, and guidance from a diverse expert advisory group of nephrologists, hepatologists, and patients, we will develop and test a HCV and CKD decision support tool. Named Project HELP (Helping Empower Liver and kidney Patients), this tool will support patients with HCV and CKD during decisions about whether, when, and how to treat each illness. The tool will (1) explain information using plain language and graphics; (2) provide a step-by-step process for thinking about treating HCV and CKD; (3) tailor relevant information to each user by asking about the individual's stage of CKD, stage of fibrosis, prior treatment, and comorbidities; (4) assess user knowledge and values for treatment choices; and (5) help individuals use and consider information appropriate to their values and needs to discuss with a clinician. A pilot study including 70 individuals will evaluate the tool's efficacy, usability, and likelihood of using it in clinical practice. Eligibility criteria will include individuals who understand and read English, who are at least 18 years old, have a diagnosis of HCV (any genotype) and CKD (any stage), and are considering treatment options.

DISCUSSION

This study can identify particular characteristics of individuals or groups that might experience challenges initiating treatment for HCV in the CKD population. This tool could provide a resource to facilitate patient-clinician discussions regarding HCV and CKD treatment options.

Centromere protein b-null mice display decreasing reproductive performance through successive generations of breeding due to diminishing endometrial glands

Centromere protein B is a highly conserved constitutive protein found at centromeres. Gene knockout studies in mice have unexpectedly identified Cenpb as a candidate gene involved in uterine function. The present study further explores the role of Cenpb in mice by intermating Cenpb-null mice over several generations. Breeding studies and analysis of uterine tissue indicate that Cenpb-null mice lose reproductive fitness over a number of generations due to a significant reduction in endometrial glands. These results suggest that Cenpb may play an important function in the short- and long-term maintenance of uterine integrity.

Survivin and the inner centromere protein INCENP show similar cell-cycle localization and gene knockout phenotype

BACKGROUND

Survivin is a mammalian protein that carries a motif typical of the inhibitor of apoptosis (IAP)proteins, first identified in baculoviruses. Although baculoviral IAP proteins regulate cell death, the yeast Survivin homolog Bir1 is involved in cell division. To determine the function of Survivin in mammals, we analyzed the pattern of localization of Survivin protein during the cell cycle, and deleted its gene by homologous recombination in mice.

RESULTS

In human cells, Survivin appeared first on centromeres bound to a novel para-polar axis during prophase/metaphase, relocated to the spindle midzone during anaphase/telophase, and disappeared at the end of telophase. In the mouse, Survivin was required for mitosis during development. Null embryos showed disrupted microtubule formation, became polyploid, and failed to survive beyond 4.5days post coitum. This phenotype, and the cell-cycle localization of Survivin, resembled closely those of INCENP. Because the yeast homolog of INCENP, Sli15, regulates the Aurora kinase homolog Ipl1p, and the yeast Survivin homolog Bir1 binds to Ndc10p, a substrate of Ipl1p, yeast Survivin, INCENP and Aurora homologs function in concert during cell division.

CONCLUSIONS

In vertebrates, Survivin and INCENP have related roles in mitosis, coordinating events such as microtubule organization, cleavage-furrow formation and cytokinesis. Like their yeast homologs Bir1 and Sli15, they may also act together with the Aurora kinase.

Bub3 gene disruption in mice reveals essential mitotic spindle checkpoint function during early embryogenesis

Bub3 is a conserved component of the mitotic spindle assembly complex. The protein is essential for early development in Bub3 gene-disrupted mice, evident from their failure to survive beyond day 6.5-7.5 postcoitus (pc). Bub3 null embryos appear normal up to day 3.5 pc but accumulate mitotic errors from days 4.5-6.5 pc in the form of micronuclei, chromatin bridging, lagging chromosomes, and irregular nuclear morphology. Null embryos treated with a spindle-depolymerising agent fail to arrest in metaphase and show an increase in mitotic disarray. The results confirm Bub3 as a component of the essential spindle checkpoint pathway that operates during early embryogenesis.

Genetic mapping of mouse centromere protein (Incenp and Cenpe) genes

Inner centromere protein (INCENP) and centromere protein E (CENPE) are two functionally important proteins of the higher eukaryotic centromere. Using a mouse Incenp genomic DNA and a mouse Cenpe cDNA to analyze recombinant inbred mouse sets, as well as interspecific backcross panels, we have mapped these genes to the proximal regions of mouse Chromosomes 19 and 6, respectively. Comparison of Cenpe and human CENPE, which maps to chromosome region 4q24-->q25, has further identified a new region of homology between the two species.

Early disruption of centromeric chromatin organization in centromere protein A (Cenpa) null mice

Centromere protein A (Cenpa for mouse, CENP-A for other species) is a histone H3-like protein that is thought to be involved in the nucleosomal packaging of centromeric DNA. Using gene targeting, we have disrupted the mouse Cenpa gene and demonstrated that the gene is essential. Heterozygous mice are healthy and fertile whereas null mutants fail to survive beyond 6.5 days postconception. Affected embryos show severe mitotic problems, including micronuclei and macronuclei formation, nuclear bridging and blebbing, and chromatin fragmentation and hypercondensation. Immunofluorescence analysis of interphase cells at day 5.5 reveals complete Cenpa depletion, diffuse Cenpb foci, absence of discrete Cenpc signal on centromeres, and dispersion of Cenpb and Cenpc throughout the nucleus. These results suggest that Cenpa is essential for kinetochore targeting of Cenpc and plays an early role in organizing centromeric chromatin at interphase. The evidence is consistent with the proposal of a critical epigenetic function for CENP-A in marking a chromosomal region for centromere formation.

Uterine dysfunction and genetic modifiers in centromere protein B-deficient mice

Centromere protein B (CENP-B) binds constitutively to mammalian centromere repeat DNA and is highly conserved between humans and mouse. Cenpb null mice appear normal but have lower body and testis weights. We demonstrate here that testis-weight reduction is seen in male null mice generated on three different genetic backgrounds (denoted R1, W9.5, and C57), whereas body-weight reduction is dependent on the genetic background as well as the gender of the animals. In addition, Cenpb null females show 31%, 33%, and 44% reduced uterine weights on the R1, W9.5, and C57 backgrounds, respectively. Production of "revertant" mice lacking the targeted frameshift mutation but not the other components of the targeting construct corrected these differences, indicating that the observed phenotype is attributable to Cenpb gene disruption rather than a neighbouring gene effect induced by the targeting construct. The R1 and W9.5 Cenpb null females are reproductively competent but show age-dependent reproductive deterioration leading to a complete breakdown at or before 9 months of age. Reproductive dysfunction is much more severe in the C57 background as Cenpb null females are totally incompetent or are capable of producing no more than one litter. These results implicate a further genetic modifier effect on female reproductive performance. Histology of the uterus reveals normal myometrium and endometrium but grossly disrupted luminal and glandular epithelium. Tissue in situ hybridization demonstrates high Cenpb expression in the uterine epithelium of wild-type animals. This study details the first significant phenotype of Cenpb gene disruption and suggests an important role of Cenpb in uterine morphogenesis and function that may have direct implications for human reproductive pathology.

Defective chromosome segregation, microtubule bundling and nuclear bridging in inner centromere protein gene (Incenp)-disrupted mice

INCENP is a chromosomal passenger protein which relocates from the centromere to thel spindle midzone during the metaphase-anaphase transition, ultimately being discarded in the cell midbody at the completion of cytokinesis. Using homologous recombination, we have generated Incenp gene-targeted heterozygous mice that are phenotypically indistinguishable from their wild-type littermates. Intercrossing the hetero-zygotes results in no live-born homozygous Incenp -disrupted progeny, indicating an early lethality. Day 3.5 affected pre-implantation embryos contain large, morphologically abnormal cells that fail to fully develop a blastocoel cavity or thrive in utero and in culture. Chromatin and tubulin immunocytochemical stainings of these and day 2.5 affected embryos reveal a high mitotic index, no discernible metaphase or anaphase stages, complete absence of midbodies, micronuclei formation, morphologically irregular macronuclei with large chromosome complements, multipolar mitotic configurations, binucleated cells, internuclear bridges and abnormal spindle bundling. The phenotype is consistent with a defect in the modulation of microtubule dynamics, severely affecting chromosome segregation and resulting in poorly resolved chromatin masses, aberrant karyokinesis and internuclear bridge formation. These latter occurrences could pose a physical barrier blocking cytokinesis.

Chromosomal localization of mouse Cenpa gene

Using a previously isolated mouse centromere protein A (Cenpa) probe, we have localized the gene to the proximal region of mouse Chromosome 5, between the known Il6 and Yes1 loci near [Adra2C-D5H4S43-Hdh]. Comparison of this localization with that of human CENPA, which maps to chromosome 2, is consistent with the presence of a new region of conserved synteny between the two species.

Centromere protein B null mice are mitotically and meiotically normal but have lower body and testis weights

CENP-B is a constitutive centromere DNA-binding protein that is conserved in a number of mammalian species and in yeast. Despite this conservation, earlier cytological and indirect experimental studies have provided conflicting evidence concerning the role of this protein in mitosis. The requirement of this protein in meiosis has also not previously been described. To resolve these uncertainties, we used targeted disruption of the Cenpb gene in mouse to study the functional significance of this protein in mitosis and meiosis. Male and female Cenpb null mice have normal body weights at birth and at weaning, but these subsequently lag behind those of the heterozygous and wild-type animals. The weight and sperm content of the testes of Cenpb null mice are also significantly decreased. Otherwise, the animals appear developmentally and reproductively normal. Cytogenetic fluorescence-activated cell sorting and histological analyses of somatic and germline tissues revealed no abnormality. These results indicate that Cenpb is not essential for mitosis or meiosis, although the observed weight reduction raises the possibility that Cenpb deficiency may subtly affect some aspects of centromere assembly and function, and result in reduced rate of cell cycle progression, efficiency of microtubule capture, and/or chromosome movement. A model for a functional redundancy of this protein is presented.

Targeted disruption of mouse centromere protein C gene leads to mitotic disarray and early embryo death

Centromere protein C (CENPC) is a key protein that has been localized to the inner kinetochore plate of active mammalian centromeres. Using gene targeting techniques, we have disrupted the mouse Cenpc gene and shown that the gene is essential for normal mouse embryonic development. Heterozygous mice carrying one functional copy of the gene are healthy and fertile, whereas homozygous embryos fail to thrive. In these embryos, mitotic arrest and gross morphological degeneration become apparent as early as the morula stage of development. The degenerating embryos demonstrate highly irregular cell and nuclear morphologies, including the presence of a large number of micronuclei. Mitotic chromosomes of these embryos display a scattered and often highly condensed configuration and do not segregate in an ordered fashion. These results describing the phenotype of the mutant mouse embryos indicate that CENPC has a direct role in the mitotic progression from metaphase to anaphase.

A mutation in the epidermal growth factor receptor in waved-2 mice has a profound effect on receptor biochemistry that results in impaired lactation

The mutant mouse waved-2 (wa-2) is strikingly similar to transforming growth factor alpha-deficient mice generated by gene targeting in embryonic stem cells. We confirm that wa-2 is a point mutation (T-->G resulting in a valine-->glycine substitution at residue 743) in the gene encoding the epidermal growth factor (EGF) receptor. wa-2 fibroblastic cells lack high-affinity binding sites for EGF, and the rate of internalization of EGF is retarded. Although the tyrosine kinase activity of wa-2 EGF receptors is significantly impaired, NIH 3T3 cells lacking endogenous EGF receptors but overexpressing recombinant wa-2 EGF receptor cDNA are mitogenically responsive to EGF. While young and adult wa-2 mice are healthy and fertile, 35% of wa-2 mice born of homozygous wa-2 mothers die of malnutrition because of impaired maternal lactation.

Mice lacking granulocyte colony-stimulating factor have chronic neutropenia, granulocyte and macrophage progenitor cell deficiency, and impaired neutrophil mobilization

Mice lacking granulocyte colony-stimulating factor (G-CSF) were generated by targeted disruption of the G-CSF gene in embryonal stem cells. G-CSF-deficient mice (genotype G-CSF-/-) are viable, fertile, and superficially healthy, but have a chronic neutropenia. Peripheral blood neutrophil levels were 20% to 30% of wild-type mice (genotype G-CSF+/+) and mice heterozygous for the null mutation had intermediate neutrophil levels, suggesting a gene-dosage effect. In the marrow of G-CSF-/- mice, granulopoietic precursor cells were reduced by 50% and there were reduced levels of granulocyte, macrophage, and blast progenitor cells. Despite G-CSF deficiency, mature neutrophils were still present in the blood and marrow, indicating that other factors can support neutrophil production in vivo. G-CSF-/- mice had reduced numbers of neutrophils available for rapid mobilization into the circulation by a single dose of G-CSF. G-CSF administration reversed the granulopoietic defect of G-CSF-/- mice. One day of G-CSF administration to G-CSF-/- mice elevated circulating neutrophil levels to normal, and after 4 days of G-CSF administration, G-CSF+/+ and G-CSF-/- marrows were morphologically indistinguishable. G-CSF-/- mice had a markedly impaired ability to control infection with Listeria monocytogenes, with diminished neutrophil and delayed monocyte increases in the blood and reduced infection-driven granulopoiesis. Collectively, these observations indicate that G-CSF is indispensible for maintaining the normal quantitative balance of neutrophil production during "steady-state" granulopoiesis in vivo and also implicate G-CSF in "emergency" granulopoiesis during infections.

Identification of germ-line chimaeras by polymerase chain reaction and isoenzyme analysis of mouse spermatozoa

In this study a rapid, simple and inexpensive procedure is described which allows potential germ-line male mice to be identified with confidence. Spermatozoa recovered by uterine washing following mating with normal female mice was analysed in two ways. First, the patterns of expression of the different isoforms of glucose phosphate isomerase were determined. Since the glucose phosphate isomerase isoforms expressed in embryo stem (ES) cell lines are frequently different from those associated with the host blastocyst, it is possible to determine the proportion of spermatozoa produced by an individual animal that was of ES cell or host-blastocyst origin. Second, DNA of spermatozoa was subjected to polymerase chain reaction (PCR) analysis using primers with specificity for the targeted mutation in the ES cells. The PCR analysis was particularly valuable in identifying germ cell chimaeras in which the contribution of ES-derived spermatozoa was significantly less than that specified by the host blastocyst.

Linkage of the murine transforming growth factor alpha gene with Igk, Ly-2, and Fabp1 on chromosome 6

TGF alpha is a mitogenic polypeptide found in the conditioned media of transformed cell lines as well as in various solid tumors. Although its physiological role in normal tissues is uncertain, the autocrine action of TGF alpha on the EGF receptor is postulated to play a role in tumorigenesis. To explore the possibility that pre-existing mouse mutants might have concordance with the mouse TGF alpha locus (Tgfa) we sought to establish the chromosomal localization of the murine TGF alpha gene. Using Southern analysis we have detected NcoI and PvuII RFLPs in the TGF alpha gene of progenitor RI mouse strains. These RFLPs have been used to analyze four different RI sets of DNA and to assign Tgfa to the 35-cM region of chromosome 6. Linkage has been established and the data suggest that the distance between Igk and wa-1 anchor loci may be less than 8 cM and that the gene order for the proximal to mid region of mouse chromosome 6 may be: Ggc-Xmmv27-[Brp-1, Lvp-1, Ms6-4]-[Igk, Ly2, Ly3 Odc-rs5, Rn7s-6, Fabp1]-[Tgfa/wa-1]-IL5-R. Homology of synteny has been further defined between the proximal region of mouse chromosome 6 and with the 2p13-p11 region of human chromosome 2 encompassing TGFA, IGK, CD8A, and FABP1.

Mice with a null mutation of the TGF alpha gene have abnormal skin architecture, wavy hair, and curly whiskers and often develop corneal inflammation

Mice homozygous for a disrupted transforming growth factor alpha (TGF alpha) gene are healthy and fertile, although some older mice show evidence of corneal inflammation. In contrast with TGF alpha +/- and +/+ animals, TGF alpha -/- mice have a pronounced waviness of the coat. Histological examination of the skin from TGF alpha -/- mice reveals a dramatic derangement of hair follicles. Mice with a disrupted TGF alpha gene also have curly whiskers, first evident on the day of birth. The phenotype of TGF alpha -/- mice is remarkably similar to that of the mouse mutant waved-1 (wa-1). Offspring resulting from crosses between TGF alpha -/- and wa-1 mice display the curly whisker-coat phenotype, indicating that the basis of the wa-1 phenotype is a mutation in the TGF alpha gene. These observations suggest that TGF alpha plays a pivotal role in determining skin architecture and in regulating hair development.

The mouse relaxin gene: nucleotide sequence and expression

Relaxin is a polypeptide hormone that has a variety of physiological effects both on remodelling of collagen and on uterine contractility. These are most apparent during pregnancy. The sequences of relaxin cDNAs derived from ovaries of late-pregnant random-bred Swiss mice have been established. Multiple subclones obtained from three independent polymerase chain reaction experiments were found to encode relaxins which were identical except at position 11 in the A chain (Ile or Val). All mouse relaxin cDNAs expressed in the ovary during pregnancy had an extra tyrosine inserted prior to the final A chain cysteine residue, a result confirmed by direct sequencing of relaxin peptides. Whilst this tyrosine insertion must have local effects on the folding of the A chain, structure-activity studies will clarify whether it perturbs functional interaction with the relaxin receptor. We have shown that there is a single relaxin gene in the mouse genome, and that expression during pregnancy occurs in the ovary but is not detectable in the placenta, uterus or fetus.

The relaxin gene is located on chromosome 19 in the mouse

Relaxin is a polypeptide hormone that exerts a variety of physiological effects during pregnancy. To investigate the possibility that known genetic mutations affecting aspects of reproductive physiology result in alterations in the structure or production of relaxin, we have determined the chromosomal location of the mouse gene. The finding of a BamHI restriction fragment length polymorphism in AKR mice enabled us to use recombinant inbred strains to make an assignment to chromosome 19. This was confirmed by Southern analysis of DNA from microcell hybrids.

In vitro production of Reichert's membrane by mouse embryo-derived parietal endoderm cell lines

We report the isolation of eight independent cell lines from preimplantation mouse embryos, which have a parietal endoderm phenotype. When grown as aggregates, these cell lines produce large amounts of a basement membrane matrix, that contains laminin, nidogen, heparan sulfate proteoglycan, collagen IV, and BM-40. The biosynthetic profiles of all eight cell lines are very similar to parietal endoderm cells in vivo which synthesize Reichert's membrane. The structure of the matrix produced by the parietal endoderm cell lines (PEC lines) resembles more closely Reichert's membrane than the Engelbreth-Holm-Swarm (EHS) tumor in susceptibility to proteolytic degradation. Since these cell lines produce large quantities of basement membrane they will be useful for structural and functional comparison of a Reichert's membrane matrix with the basement membrane produced by the EHS tumor.

Studies of developing human hair shaft cells in vitro

Methods for studying aspects of hair formation in vitro have been devised on the basis of isolating developing hair shaft cells. These cells were obtained using a sterile microdissection technique. Plucked anagen follicles were dissected free of surrounding tissues (inner and outer root sheaths), and presumptive hair shaft cells (including germinal epithelia) were cultured directly on mammalian fibroblasts or in media preconditioned by fibroblasts. Specimens were cultured either as dispersions or in whole tissue pieces. Trypsinized whole tissue specimens in culture were sometimes observed to form increased bulk, while dispersed cells appeared to elongate and form larger colonies. In sections of these colonies examined by transmission electron microscopy, intracellular hard keratin intermediate filaments (IFs) together with IF-matrix hard keratin complexes were observed. Radiolabelled cysteine [35S] was added to cultures (3-20 days), showing a continuing but reduced synthesis of hard keratin IF proteins (low-sulfur) over the period of study. Matrix protein (high-sulfur) production was drastically reduced after 3 days. Monoclonal antibodies directed against hair keratin IF components were used in Western transfers and immunofluorescent studies to help assess the specificity of proteins synthesized in culture. Our observations indicate that, with some refinement, the presently described methods enable preparation of hair shaft precursor cells suitable for observing certain hair-forming processes in vitro.

Non-neutralizing monoclonal antibodies to a trypsin-sensitive site on the major glycoprotein of rotavirus which discriminate between virus serotypes

Monoclonal antibodies were derived to a human rotavirus purified from stools. Three of the antibodies immunoprecipitated the rotavirus outer capsid glycoprotein gp 34 and were non-neutralizing. These antibodies reacted by enzyme immunoassay with cultivable rotaviruses showing the "long" RNA electropherotype but were inefficient as detectors of "long" RNA pattern rotaviruses in stools. Treatment of SA 11 rotavirus with 7.5 micrograms/ml porcine trypsin for 30 minutes at 37 degrees C irreversibly reduced binding of the antibodies to SA 11 rotavirus in enzyme immunoassays by 50 per cent. Binding was abolished in the presence of rotavirus-negative faecal extracts. These results indicate that non-neutralizing sites on gp 34 of rotaviruses can vary with RNA electropherotype and serotype, and that levels of trypsin currently in use to assist growth of rotaviruses in cell culture may alter the serological profile of the viruses.

Purification of polymeric immunoglobulin from cell culture supernatants by affinity chromatography using secretory component

Human secretory component bound covalently to Sepharose 4B has been used as an affinity adsorbent to isolate and purify polymeric immunoglobulin from cell culture supernatants. The method was used to isolate murine IgM isotype anti-trinitrophenol antibody and rat IgM isotype anti-lymphocyte antibody from hybridoma cell culture supernatants. Gel filtration of the eluted antibodies followed by enzyme immunoassay showed that all recovered IgM was of pentameric molecular size. Murine IgA isotype anti-dinitrophenol antibody and murine IgA anti-human rotavirus antibody were isolated from cell culture supernatants of a plasmacytoma and a hybridoma respectively. Most of the IgA recovered following affinity adsorption with secretory component was of greater molecular size than dimer. Murine IgG was not adsorbed by secretory component bound to Sepharose. Eluted antibody retained antigen binding activity. Affinity chromatography using human secretory component bound covalently to a solid phase provides an antigen-independent technique for purification of murine and rat IgA and IgM polymeric immunoglobulin from cell cultures.

A differentiation-defective concanavalin-A-resistant variant of a pluripotent embryonal carcinoma cell line

A concanavalin-A(Con A)-resistant variant of the pluripotent mouse embryonal carcinoma cell line, PSA1-NG2, was isolated. This variant, designated NG2-2.16, fails to exhibit the extensive spontaneous differentiation displayed by PSA1-NG2 in colonies in vitro and in tumours in vivo. The molecular nature of the defect in NG2-2.16 cells was not revealed by quantitative studies of the binding, uptake and metabolism of tritiated Con A, or by Western blotting of membrane and whole cell homogenates, thus indicating the defect to be the result of a more subtle molecular alteration. Statistical evidence suggests that the same mutation is responsible for both the Con A resistance and the lack of spontaneous differentiation. NG2-2.16 cells were induced to differentiate by exposure to retinoic acid, suggesting that the mutation affects the regulation of differentiation rather than the potential for differentiation.

Neutralizing monoclonal antibodies to human rotavirus and indications of antigenic drift among strains from neonates

Cells producing neutralizing monoclonal antibodies to a serotype 3 human neonatal rotavirus strain RV-3 were derived by fusion of hyperimmunized mouse spleen cells with mouse myeloma cells. As ascites fluid, three rotavirus-neutralizing monoclonal antibodies were characterized by hemagglutination inhibition and reacted with 17 cultivable mammalian rotaviruses representing five virus serotypes, by fluorescent focus neutralization and enzyme immunoassay. Two antibodies, Mab RV-3:1 and Mab RV-3:2, reacted with the seven serotype 3 rotaviruses only. Mab RV-3:1 was shown to bind to the outer capsid glycoprotein gp34 of rotavirus when variants of SA 11 rotavirus were used, and it therefore appears to react with the major neutralization epitope of serotype 3 rotaviruses. The antibody Mab RV-3:3 was specific for an epitope of RV-3 rotavirus not present on any other rotavirus of any serotype tested, including another neonatal isolate of identical RNA electropherotype isolated from the same ward of the same hospital as RV-3 3 months earlier. These two viruses were also distinguishable by fluorescent focus neutralization, using antiserum to RV-3 virus. Western blot analysis showed binding of Mab RV-3:3 to the trypsin cleavage product of the outer capsid protein p86 of RV-3. This suggests that antigenic drift may have occurred among neonatal rotaviruses in Melbourne. These monoclonal antibodies will be useful in serotyping assays of rotaviruses directly in stool samples, and in further analysis of antigenic variation within the serotype.

Elimination of Mycoplasma orale from the human hepatoma cell line, PLC/PRF/5

We have tried without success to eliminate M. orale from a human hepatoma line, PLC/PRF/5, using five different methods. We report here the successful elimination of the contamination by a modification of the technique of Marcus et al. [1] using 5-bromodeoxy-uridine (BrdU) instead of 5-bromo-uracil (5-BrUra) and light. We believe that this method may prove useful when rare and valuable cell lines carry the more common mycoplasma contaminant M. orale.