Determination of Vegetal Proteins in Milk Powder by Sodium Dodecyl Sulfate–Capillary Gel Electrophoresis: Interlaboratory Study

An interlaboratory study, with the participation of 8 laboratories, was conducted to evaluate a sodium dodecyl sulfate–capillary gel electrophoresis method for determination of adulteration of milk powder with soy and pea proteins. Calibration standards (0–8%, w/w, soy and pea protein in total protein) and adulterated skim milk powders (0–5%, w/w, soy and pea proteins in total protein) were produced. Vegetal proteins were determined after removal of milk proteins by pretreatment of the samples with tetraborate–EDTA buffer, pH 8.3. Repeatability standard deviations ranged from 9 to 15% and reproducibility standard deviations ranged from 25 to 30% in the samples containing 5% vegetal protein in total protein.

Gene expression profiling in aggressive digital papillary adenocarcinoma sheds light on the architecture of a rare sweat gland carcinoma

BACKGROUND

Sweat gland carcinomas are rare cutaneous adnexal malignancies. Aggressive digital papillary adenocarcinoma (ADPA) represents a very rare subentity, thought to arise almost exclusively from the sweat glands of the fingers and toes. The aetiology of sweat gland carcinomas and ADPA is largely unknown. ADPAs are most likely driven by somatic mutations. However, somatic mutation patterns are largely unexplored, creating barriers to the development of effective therapeutic approaches to the treatment of ADPA.

OBJECTIVES

To investigate the transcriptome profile of ADPA using a sample of eight formalin-fixed, paraffin-embedded tissue samples of ADPA and healthy control tissue.

METHODS

Transcriptome profiling was performed using the Affymetrix PrimeView Human Gene Expression Microarray and findings were validated via reverse transcription of RNA and real-time quantitative polymerase chain reaction.

RESULTS

Transcriptome analyses showed increased tumour expression of 2266 genes, with significant involvement of cell cycle, ribosomal and crucial cancer pathways. Our results point to tumour overexpression of FGFR2 (P = 0·001).

CONCLUSIONS

The results indicate the involvement of crucial oncogenic driver pathways, highlighting cell cycle and ribosomal pathways in the aetiology of ADPA. Suggested tumour overexpression of FGFR2 raises the hope that targeting the fibroblast growth factor (FGF)/FGF receptor axis might be a promising treatment for ADPA and probably for the overall group of sweat gland carcinomas.

Excision of HIV-1 DNA by gene editing: a proof-of-concept in vivo study

A CRISPR/Cas9 gene editing strategy has been remarkable in excising segments of integrated HIV-1 DNA sequences from the genome of latently infected human cell lines and by introducing InDel mutations, suppressing HIV-1 replication in patient-derived CD4+ T-cells, ex vivo. Here, we employed a short version of the Cas9 endonuclease, saCas9, together with a multiplex of guide RNAs (gRNAs) for targeting the viral DNA sequences within the 5'-LTR and the Gag gene for removing critically important segments of the viral DNA in transgenic mice and rats encompassing the HIV-1 genome. Tail-vein injection of transgenic mice with a recombinant Adeno-associated virus 9 (rAAV9) vector expressing saCas9 and the gRNAs, rAAV:saCas9/gRNA, resulted in the cleavage of integrated HIV-1 DNA and excision of a 978 bp DNA fragment spanning between the LTR and Gag gene in the spleen, liver, heart, lung and kidney as well as in the circulating lymphocytes. Retro-orbital inoculation of rAAV9:saCas9/gRNA in transgenic rats eliminated a targeted segment of viral DNA and substantially decreased the level of viral gene expression in circulating blood lymphocytes. The results from the proof-of-concept studies, for the first time, demonstrate the in vivo eradication of HIV-1 DNA by CRISPR/Cas9 on delivery by an rAAV9 vector in a range of cells and tissues that harbor integrated copies of viral DNA.

Factors that Influence Mycobacterium bovis Infection in Red Deer and Wild Boar in an Epidemiological Risk Area for Tuberculosis of Game Species in Portugal

Bovine tuberculosis (bTB) is a worldwide zoonotic disease of domestic and wild animals. Eradication has proved elusive in those countries with intensive national programmes but with ongoing transmission between wildlife and cattle. In Portugal, a high-risk area for bTB was defined and specific measures implemented to assess and minimize the risk from wildlife. Data from the 2011 to 2014 hunting seasons for red deer (Cervus elaphus) and wild boar (Sus scrofa) were analysed with bovine demographic and bTB information to assess factors that determined the occurrence and distribution of bTB in both species. The likelihood of bTB-like lesions in wild boar was positively associated with density of red deer, wild boar and cattle, while for red deer, only their density and age were significant factors. The likelihood of Mycobacterium bovis isolation in wild boar was associated with density of cattle and red deer and also with the anatomical location of lesions, while for red deer, none of the variables tested were statistically significant. Our results suggest that, in the study area, the role of red deer and wild boar may be different from the one previously suggested by other authors for the Iberian Peninsula, as red deer may be the driving force behind M. bovis transmission to wild boar. These findings may assist the official services and game managing bodies for the management of hunting zones, what could also impact the success of the bTB eradication programme.

An assessment of the feasibility of a poultry tracing scheme for smallholders in Vietnam

Tracing movements could assist the implementation of bio-containment measures during a disease outbreak. To evaluate the potential for implementing a tracing system for a poultry supply chain in northern Vietnam, a four-month longitudinal study was conducted to identify marketing practices associated with poultry traceability. Poultry sold in batches were traced between farms and markets, and their traceability was assessed upon market arrival. A total of 315 batches were released from the farms; 37% arrived at a market, from which 57.3% were 'traceable'. The results of the multivariable analysis showed that traceability was associated with farms operating through no more than two traders (Odds ratio [OR] = 5.97, 95% CI 1.15-30.92) and batches brought to the market on the day of purchase (OR = 4.05, 95% CI 1.23-13.27). No specific incentives were provided to farmers or traders. Results suggest that there is potential for implementing a poultry traceability scheme, although the tracing methodology should be refined.

Impacts of avian influenza virus on animal production in developing countries

Abstract

This paper reviews the (predominantly grey) literature on impacts of highly pathogenic avian influenza (HPAI) strain H5N1 and control responses on the livestock sector and associated industries in developing countries. The authors distinguish between impacts that arise directly through HPAI-related morbidity and mortality, those that are a consequence of public intervention to control or eradicate HPAI, and impacts that are mediated through market reactions. The paper further considers how these impacts propagate up- and downstream through related supply and distribution networks, how short-term reactions are followed by longer-term adjustments, how impacts include direct cost elements and foregone income, and why losses to the poultry sector will, at least to some extent, be 'passed on' on the one hand, for example through compensation, and, on the other hand, be compensated for by gains in other livestock subsectors. Differences in methodology applied in the reviewed reports result in a lack of comparability of estimates for HPAI 'costs/impacts' across countries and even within countries and are compounded by information deficits. Despite these shortcomings, the literature permits some significant conclusions to be drawn on the relative importance of direct and indirect impacts and on their distribution across different types of poultry producers. The paper ends by outlining directions of future research that combine epidemiology and economics to provide a framework for disease control decision-making.

p27(SJ), a novel protein in St John's Wort, that suppresses expression of HIV-1 genome

Transcription of the HIV-1 genome is controlled by the cooperation of viral regulatory proteins and several host factors which bind to specific DNA sequences within the viral promoter spanning the long terminal repeat, (LTR). Here, we describe the identification of a novel protein, p27(SJ), present in a laboratory callus culture of Hypericum perforatum (St John's Wort) that suppresses transcription of the HIV-1 genome in several human cell types including primary culture of microglia and astrocytes. p27(SJ) associates with C/EBPbeta, a transcription factor that regulates expression of the HIV-1 genome in macrophages and monocytic cells, and the viral transactivator, Tat. The association of p27(SJ) with C/EBPbeta and Tat alters their subcellular localization, causing their accumulation in the perinuclear cytoplasmic compartment of the cells. Fusion of a nuclear localization signal to p27(SJ) forces its entry into the nucleus and diminishes the capacity of p27(SJ) to suppress Tat activity, but does not alter its ability to suppress C/EBPbeta activation of the LTR. Results from binding assays showed the inhibitory effect of p27(SJ) on C/EBPbeta interaction with DNA. Finally, our results demonstrate that expression of p27(SJ) decreases the level of viral replication in HIV-1-infected cells. These observations suggest the potential for the development of a therapeutic advance based on p27(SJ) protein to control HIV-1 transcription and replication in cells associated with HIV-1 infection in the brain.

Somatic mosaicism and variable penetrance in doublecortin-associated migration disorders

X-linked isolated lissencephaly sequence (XLIS) and subcortical band heterotopia (SBH) are allelic disorders caused by mutations in the doublecortin (DCX) gene. This genetic analysis of seven families revealed four novel mutations in the DCX gene. The authors detected a high rate of somatic mosaicism in male and female patients with variable penetrance of bilateral SBH including nonpenetrance in a heterozygous woman. In addition, the authors implemented prenatal diagnosis in a family with SBH/XLIS.

Identification of CCK-B/gastrin receptor splice variants in human peripheral blood mononuclear cells

There is increasing evidence for a direct interaction of the enteric nervous and immune system. Receptors for neuropeptides such as VIP, somatostatin, and substance P have been characterised in human immuno-haematopoietic cells but little is known about the functional significance and expression of receptors for cholecystokinin (CCK) on cells of the immune system. There are only few studies that describe the expression of CCK receptors on human leukaemia-derived cell lines but the receptor structure and function in normal leukocytes have not been clearly established. We therefore sought to determine CCK receptor expression, structure, and function in nontransformed human peripheral blood mononuclear cells.Full-length cDNA clones encoding the human CCK-A and CCK-B/gastrin receptor are expressed in peripheral blood mononuclear cells from healthy volunteers without haematopoietic malignancy. In addition to wild-type CCK-B/gastrin receptor cDNAs, we isolated a splice variant with an in frame insertion of 69 amino acids within its putative third intracellular receptor loop. Dideoxy sequence analysis revealed that the cDNA of this splice variant comprises exons 1-4 but retains intron 4 (207 bp) in the absence of mutations within the splice donor sites. Transient expression of this splice variant in COS-7 cells reveals wild-type affinity for CCK-8, Gastrin-17, and antagonist L-365,260. Affinity for glycine-extended gastrin-17 was not increased when compared to the wild-type CCK-B/gastrin receptor. In vitro, gastrin decreased 3H-thymidine labelling in phytohaemagglutinin-pretreated mononuclear cells at a half-maximally effective concentration of 1.5 nM. We also isolated a cDNA encoding another splice variant of the CCK-B/gastrin receptor with a 158 bp deletion of the entire exon 4 sequence. We conclude that wild-type transcripts of both CCK receptor subtypes and splice variants of the CCK-B/gastrin receptor are expressed in nontransformed human mononuclear cells and that gastrin exhibits antiproliferative effects.

Effect of limited hydrolysis on the interfacial rheology and foaming properties of β-lactoglobulin A

Hydrolysis of beta-lactoglobulin (beta-Lg), genetic variant A, using a serine protease specific for glutamic and aspartic acid residues from Bacillus licheniformis (BLP), resulted in improved foam overrun and foam stability. Limited hydrolysis (19-26% hydrolysed beta-Lg) led to a more rapid increase in the viscoelastic properties of air/water interfacial films and a concomitant increase in foam overrun compared with intact beta-Lg, presumably due to increased exposure of hydrophobic areas. The increased exposure did not, however, cause formation of an interfacial layer with increased viscoelastic properties. More extended hydrolysis (86% hydrolysed beta-Lg) resulted in a higher initial overrun than the unhydrolysed sample and the best foam stability. The interfacial elasticity and viscosity, though, was the lowest observed. Thus, high maximum values of these interfacial properties are not necessary prerequisites for formation of a voluminous and stable foam.

Molecular self-assembly of partially hydrolysed alpha-lactalbumin resulting in strong gels with a novel microstructure

Gelation of alpha-lactalbumin (alpha-la) incubated with a protease from Bacillus licheniformis (BLP) at 50 degrees C for 4 h was monitored using small oscillatory shear and the large deformation properties of final gels were characterized by uniaxial compression. Transmission electron microscopy was used to visualize the microstructure. Gels made from alpha-la (10 g/l) using BLP were almost transparent, although somewhat whitish, and they were more than 20 times stiffer (measured as complex modulus) than equivalent gels made from beta-lactoglobulin (beta-lg) at the same concentration. The microstructure of the gels consisted of non-branching, apparently hollow strands with a uniform diameter close to 20 nm, similar in overall structure to microtubules. Adding Ca2+ in amounts of 50 or 100 mM changed the spatial distribution of the strands and resulted in a reduction in the failure stress recorded in uniaxial compression. Apart from affecting the microstructure, Ca2+ was shown to be essential for the formation of the gels. It is proposed. that the mechanism behind the self-assembly of the partially hydrolysed alpha-la into long tubes is a spatially restricted creation of ionic bonds between Ca2+ and carboxyl acid groups on peptide fragments resulting from the action of BLP on alpha-la. Proteolysis of alpha-la with BLP in the presence of Ca2+ thus results in formation of a strong gel with a microstructure not previously observed in food protein systems.

Effect of partial hydrolysis with an immobilized proteinase on thermal gelation properties of beta-lactoglobulin B

We have investigated the influence of partial hydrolysis with an immobilized proteinase from Bacillus licheniformis on the thermal gelation of isolated beta-lactoglobulin B. Gelation behaviour was determined by dynamic rheological measurements (small deformation) and the gels were characterized with respect to microstructure and water-holding properties. A fine-stranded gel with a complex modulus of approximately 2000 Pa was formed from beta-lactoglobulin (50 g/l in 75 mM-Tris-HCl, pH 7.5). Limited hydrolysis prior to thermal gelation resulted in coarser gels with thicker protein strands and larger pores. Gel structure correlated with its permeability, proton mobility and water-holding capacity. Total stiffness gel increased with low degrees of hydrolysis, but decreased after prolonged hydrolysis. Maximal gel stiffness was 1.5-fold that gels made from of unhydrolysed beta-lactoglobulin. This was much lower than the stiffening effect obtained after partial hydrolysis of whey protein isolate, showing that the gel strengthening effect of partial hydrolysis was depedent on the protein composition and/or the hydrolysis and gelatin conditions. A mechanism to explain the observed effects of hydrolysis on gelation and gel properties is presented.

Pituitary neoplasia induced by expression of human neurotropic polyomavirus, JCV, early genome in transgenic mice

In recent years, there has been mounting evidence pointing to the association of polyomaviruses with a wide range of human cancers. The human neurotropic polyomavirus, JCV, infecting greater than 75% of the human population produces a regulatory protein named T-antigen which is expressed at the early phase of viral lytic infection and plays a critical role in completion of the viral life cycle. Furthermore, this protein has the ability to transform neural cells in vitro and its expression has been detected in several human neural-origin tumors. To further investigate the oncogenic potential of the JCV early protein in vivo, transgenic mice expressing JCV T-antigen under the control of its own promoter were generated. Nearly 50% of the animals developed large, solid masses within the base of the skull by 1 year of age. Evaluation of the location as well as histological and immunohistochemical data suggest that the tumors arise from the pituitary gland. As T-antigen is known to interact with several cell cycle regulators, the neoplasms were analysed for the presence of the tumor suppressor protein, p53. Immunoprecipitation/Western blot analysis demonstrated overexpression of wild-type, but not mutant p53 within tumor tissue. In addition, co-immunoprecipitation established an interaction between p53 and T-antigen and overexpression of p53 downstream target protein, p21/WAF1. This report describes the analysis of inheritable pituitary adenomas induced by expression of the human polyomavirus, JCV T-antigen in transgenic mice where T-antigen disrupts the p53 pathway by binding to and sequestering wild-type p53. This animal model may serve as a useful tool to further evaluate mechanisms of tumorigenesis by JCV T-antigen.

Identification of a novel p53 mutation in JCV-induced mouse medulloblastoma

Medulloblastoma, a malignant invasive tumor of the cerebellum, is one of the most common neoplasms of the nervous system in children. Utilization of the human neurotropic virus JC virus (JCV) early gene T-antigen allowed the development of a transgenic animal that models human medulloblastoma. Here we describe the characterization of two distinct populations of cells derived from the JCV-induced mouse medulloblastoma. Results from immunohistochemical and biochemical studies revealed the expression of T-antigen in some but not all tumor cells. In T-antigen-producing cells, T-antigen was found in association with wild-type p53 and pRb, two tumor suppressors that control cell growth and differentiation. In cells that lack expression of T-antigen, a novel mutant p53 with a deletion between residues 35 and 123 was detected. Morphological differences were observed between the two populations of cells, though there was no significant difference in their growth rates. However, subcutaneous transplantation of the T-antigen-positive, but not T-antigen-negative, cells resulted in the development of massive tumors in experimental animals. In light of earlier reports on the association of JCV with human medulloblastoma, the mouse cell lines described in this study may provide a valuable tool for deciphering the pathways involved in the formation and progression of medulloblastoma.

Steady-state kinetics and thermodynamics of the hydrolysis of beta-lactoglobulin by trypsin

Hydrolysis of beta-lactoglobulin (in an equimolar mixture of the A and B variant) by trypsin in neutral aqueous solution [pH 7.7 at 25 degrees C, ionic strength 0.08 (NaCl)] was followed by capillary electrophoresis and thermodynamic parameters derived from a Michaelis-Menten analysis of rate data obtained at 10, 20, 30, and 40 degrees C for disappearance of beta-lactoglobulin. Enthalpy of substrate binding to the enzyme and the energy of activation for the catalytic process were found to have the values, DeltaH(bind) = -28 +/- 4 kJ mol(-)(1) and E(a) = 51 +/- 18 kJ mol(-)(1), respectively. Thus, beta-lactoglobulin shows an enthalpy of activation for free substrate reacting with free enzyme of about 21 kJ mol(-)(1), corresponding to a transition state stabilization of 60 kJ mol(-)(1) when compared to acid-catalyzed hydrolysis. The catalytic efficiency of trypsin in hydrolysis of beta-lactoglobulin is increased significantly by temperature; however, this effect is partly counteracted by a weaker substrate binding resulting in an increase by only 25%/10 degrees C in overall catalytic efficiency.

Standardized reaction times used to describe the mechanism of enzyme-induced gelation in whey protein systems

Whey protein isolate (WPI), either untreated or pretreated at 80 degrees C for 30 min, was incubated with a proteinase from Bacillus licheniformis until a gel was formed. Standardized reaction times, directly linked to the degree of hydrolysis, were obtained from plots of the relative amount of peptides released v. reaction time obtained under different conditions (enzyme concentration, temperature, pH, NaCl addition). This provided a connection between the gelation profile and the degree of hydrolysis. In the case of untreated WPI, gelation occurred at lower degrees of proteolysis when the enzyme concentration was decreased, demonstrating that a rate-limiting aggregation process occurred at the same time as the proteolysis in a manner similar to the renneting of milk. This was not the case for preheated WPI, when gelation was found to take place at a constant degree of proteolysis, independent of the enzyme concentration. In this case, the mechanism could be described by assuming the thermally induced aggregates present in this substrate had progressively more stabilizing peptide segments shaved off, resulting in increased attraction between individual aggregates that ultimately led to gelation. Results obtained at 40-60 degrees C supported this, as we found no effect of temperature on the degree of proteolysis at gelation for the untreated WPI, whereas the degree of proteolysis decreased with increasing temperature when heated WPI was hydrolysed. The effect of pH and NaCl addition on the process was to reduce repulsion between the aggregating species so that gelation was induced at a decreased degree of proteolysis.

Identification of peptides in aggregates formed during hydrolysis of beta-lactoglobulin B with a Glu and Asp specific microbial protease

The purpose of the present study was to identify the peptides responsible for aggregate formation during hydrolysis of beta-lactoglobulin by BLP at neutral pH. Hydrolysates taken at various stages of aggregate formation were separated into a precipitate and a soluble phase and each was analyzed by CE and mass spectrometry. The aggregates consisted of six to seven major peptides of which four were tentatively identified. The peptides were positively charged at neutral pH and had a high charge-to-mass ratio at low pH. The fragment f135-158 seemed to be the initiator of aggregation, since it was present at high concentration in the aggregates at all stages, and the concentration of this peptide remained low in the supernatant. F135-158 contains several basic and acid amino acids alternating with hydrophobic amino acids, which is in accordance with formation of noncovalently linked aggregates, as previously shown.

Association of JC virus large T antigen with myelin basic protein transcription factor (MEF-1/Puralpha) in hypomyelinated brains of mice transgenically expressing T antigen

Progressive multifocal leukoencephalopathy (PML) is a fatal demyelinating disease caused by cytolytic destruction of oligodendrocytes, the myelin-producing cells of the central nervous system, by the human neurotropic JC virus (JCV). The early protein of JCV, T antigen, which is produced at the early stage of infection, is important for orchestrating the events leading to viral lytic infection and cytolytic destruction of oligodendrocytes. Results from transgenic mouse studies, however, have revealed that, in the absence of lytic infection, this protein can induce brain hypomyelination and suppression of myelin gene expression. Since expression of the gene encoding myelin basic protein, the major component of myelin, can be regulated by a DNA-binding transcription factor, MEF-1/Puralpha, (Puralpha), we have examined the level of this protein in transgenic mouse brains. Results from immunoprecipitation and Western blots showed that while there was no drastic decrease in the level of MEF-1/Puralpha in transgenic mouse brains, JCV T antigen was found in a complex with MEF-1/Puralpha. Immunohistological studies revealed abnormal oligodendrocytes in white matter, where MEF-1/Puralpha and T antigen were detected. Furthermore, immunogold electron microscopic studies revealed that Puralpha and T antigen are colocalized in the nucleus of the oligodendrocytes and in hippocampal neurons. Interestingly, results from cell culture studies revealed that incubation of oligodendrocytes with JCV led to a drastic decrease in the level of MEF-1/Puralpha protein. These observations provide insight into the molecular pathogenesis of PML and support a model for a dual effect of JCV on inducing hypomyelination by (i) affecting myelin gene expression via interaction of JCV T antigen and the myelin gene transcription factor, MEF-1/Puralpha, and (ii) causing a decline in the level of the host regulatory proteins, including MEF-1/Puralpha, which are involved in myelin gene expression.

Human ubiquitous JCV(CY) T-antigen gene induces brain tumors in experimental animals

JCV is a papovavirus which is widespread in the human population. The prototype Mad-1 variant of JCV induces a fatal demyelinating disease of the central nervous system (CNS) called Progressive Multifocal Leukoencephalopathy (PML) in immunosuppressed individuals. The unique tropism of JCV (Mad-1) to the CNS is attributed to the tissue-specific regulation of the viral early promoter which is responsible for the production of the viral regulatory protein, T-antigen. The archetype form of this virus, JCV(CY), which has been repeatedly isolated from the urine of PML and non-PML individuals, is distinct from JCV(Mad-1) in the structural organization of the regulatory sequence. To characterize the tissue specific expression of JCV(CY) and to investigate its potential in inducing disease, transgenic mice containing the early region of JCV(CY) were generated. Some of these mice between 9-13 months of age exhibited signs of illness as manifested by paralysis of rear limbs, hunched posture, and poor grooming. Neuropathological examination indicated no sign of hypomyelination of the brain, but surprisingly, revealed the presence of primitive tumors originating from the cerebellum and the surrounding brain stem. The tumor masses also infiltrated the surrounding tissue. Results from RNA and protein studies revealed a high level of T-antigen mRNA expression in hindbrains of clinically normal and affected transgenic mice. However, higher levels of T-antigen RNA and protein were detected in brains of the animals exhibiting severe illness. The close resemblance of JCV(CY) induced tumor in transgenic mice to the human medulloblastoma/primitive neuroectodermal tumor (PNETs) in location, histologic appearance, and expression of marker proteins strongly suggests the utility of this novel animal model for the study of human brain tumors.

Oncogenic potential of human neurotropic papovavirus, JCV, in CNS

The human polyomavirus, JCV, is the causative agent of Progressive Multifocal Leukoencephalopathy (PML), a fatal human demyelinating disease. PML results from the cytolytic destruction of oligodendrocytes, the myelin-producing cells of the nervous system. JCV has also been shown to be tumorigenic in several animal models. Transgenic mice expressing the JCV early protein, T-antigen, develop poorly differentiated neural crest origin tumours. Intracerebral inoculation of JCV into newborn hamsters induces medulloblastomas, astrocytomas, and primitive neuroectodermal tumours. Further, inoculation of the virus into the brains of non-human primates, owl and squirrel monkeys, results in astrocytomas and glioblastoma multiforme. Several case reports have associated JCV with human CNS tumours in patients with concomitant PML, and one such report has detected JCV in a glial tumour in the absence of PML. The induction of neural origin tumours by JCV has been studied in transgenic mice harbouring the early genome of the virus. Alterations in the level and function of tumour suppressor proteins p53 and Rb, as well as associated cell cycle regulators, have been detected in tumour tissue from JCV T-antigen transgenic mice. Possible mechanisms by which JCV may exert its oncogenic potential by alteration of cellular growth control pathways in both humans and experimental animals are discussed.

Selective disruption of genes transiently induced in differentiating mouse embryonic stem cells by using gene trap mutagenesis and site-specific recombination

A strategy employing gene trap mutagenesis and site-specific recombination (Cre/loxP) has been used to identify genes that are transiently expressed during early mouse development. Embryonic stem cells expressing a reporter plasmid that codes for neomycin phosphotransferase and Escherichia coli LacZ were infected with a retroviral gene trap vector (U3Cre) carrying coding sequences for Cre recombinase (Cre) in the U3 region. Activation of Cre expression from integrations into active genes resulted in a permanent switching between the two selectable marker genes and consequently the expression of beta-galactosidase (beta-Gal). As a result, clones in which U3Cre had disrupted genes that were only transiently expressed could be selected. Moreover, U3Cre-activating cells acquired a cell autonomous marker that could be traced to cells and tissues of the developing embryo. Thus, when two of the clones with inducible U3Cre integrations were passaged in the germ line, they generated spatial patterns of beta-Gal expression.

Effect of different East Coast Fever control strategies on fertility, milk production and weight gain of Sanga cattle in the Central Province of Zambia

Five different East Coast Fever (ECF) (Theileria parva infection) control strategies, based on tick control and/or ECF immunization, were tested in groups of traditionally managed Sanga cattle in the Central Province of Zambia over a period of 2.5 years. Two groups were kept under intensive tick control (sprayed weekly), one group immunized and one non-immunized. Two further groups were under no tick control, one group immunized and one non-immunized, while a fifth group was immunized against ECF and maintained under strategic tick control (18 sprays per year). Tick control increased milk production and weight gain but not fertility. Immunization had neither marked detrimental nor beneficial effects on the cattle productivity. The combination of strategic tick control and immunization resulted in the highest level of production and at the same time reduced the potential risk from other tick-borne diseases.

Role of cell cycle regulators in tumor formation in transgenic mice expressing the human neurotropic virus, JCV, early protein

Transgenic mice harboring the early genome from the human neurotropic JC virus, JCV, develop massive abdominal tumors of neural crest origin during 6-8 months after birth and succumb to death a few weeks later. The viral early protein, T-antigen, which possesses the ability to transform cells of neural origin, is highly expressed in the tumor cells. Immunoblot analysis of protein extract from tumor tissue shows high level expression of the tumor suppressor protein, p53, in complex with T-antigen. Expression of p21, a downstream target for p53, which controls cell cycle progression by regulating the activity of cyclins and their associated kinases during the G1 phase, is extremely low in the tumor cells. Whereas the level of expression and activity of cyclin D1 and its associated kinase, cdk6, was modest in tumor cells, both cyclin A and E, and their kinase partners, cdk2 and cdk4, were highly expressed and exhibited significant kinase activity. The retinoblastoma gene product, pRb, which upon phosphorylation by cyclins:cdk induces rapid cell proliferation, was found in the phosphorylated state in tumor cell extracts, and was detected in association with JCV T-antigen. The transcription factor, E2F-1, which dissociates from the pRb-E2F-1 complex and stimulates S phase-specific genes upon phosphorylation of pRb and/or complexation of pRb with the viral transforming protein, was highly expressed in tumor cells. Accordingly, high level expression of the E2F-1-responsive gene, proliferating cell nuclear antigen (PCNA), was detected in the tumor cells. These observations suggest a potential regulating pathway that, upon expression of JCV T-antigen, induces formation and progression of tumors of neural origin in a whole animal system.

Molecular characterization of human zyxin

Zyxin is a component of adhesion plaques that has been suggested to perform regulatory functions at these specialized regions of the plasma membrane. Here we describe the isolation and characterization of cDNAs encoding human and mouse zyxin. Both the human and mouse zyxin proteins display a collection of proline-rich sequences as well as three copies of the LIM domain, a zinc finger domain found in many signaling molecules. The human zyxin protein is closely related in sequence to proteins implicated in benign tumorigenesis and steroid receptor binding. Antibodies raised against human zyxin recognize an 84-kDa protein by Western immunoblot analysis. The protein is localized at focal contacts in adherent erythroleukemia cells. By Northern analysis, we show that zyxin is widely expressed in human tissues. The zyxin gene maps to human chromosome 7q32-q36.

Detection of JC virus DNA sequence and expression of the viral oncoprotein, tumor antigen, in brain of immunocompetent patient with oligoastrocytoma

We describe molecular and clinical findings in an immunocompetent patient with an oligoastrocytoma and the concomitant presence of the human papovavirus, JC virus (JCV), which is the etiologic agent of the subacute, debilitating demyelinating disease, progressive multifocal leukoencephalopathy. Histologic review revealed a glial neoplasm consisting primarily of a moderately cellular oligodendroglioma with distinct areas of a fibrillary astrocytoma. Immunohistochemical analysis revealed nuclear staining of tumor cells with antibodies against the viral oncoprotein [tumor antigen (T antigen)], the proliferation marker (Ki67), and the cellular proliferation regulator (p53). Using primers specific to the JCV control region, PCR yielded amplified DNA that was identical to the control region of the Mad-4 strain of the virus. PCR analysis demonstrated the presence of the genome for the viral oncoprotein, T antigen, and results from primer extension studies revealed synthesis of the viral early RNA for T antigen in the tumor tissues. The presence of viral T antigen in the tumor tissue was further demonstrated by immunoblot assay. To our knowledge, this is the first report of the presence of JCV DNA, RNA, and T antigen in tissue in which viral T antigen is localized to tumor cell nuclei and suggests the possible association of JCV with some glial neoplasms.

Evidence that the soluble factors secreted by activated immune cells suppress replication of human neurotropic JC virus DNA in glial cells

Coordination of the immune response to viral infection and disease in the brain is believed to involve bidirectional interaction between the immune system and the central nervous system (CNS). Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease of the CNS that generally affects patients exhibiting an immunocompromised condition due to various illnesses. The human polyomavirus, JCV, which infects greater than 70% of the adult population is the etiological agent of this disease. Infection with JCV occurs during childhood and the virus remains in the latent state with no apparent clinical signals. However, under immunocompromised conditions, the virus enters the lytic cycle, and upon cytolytic destruction of glial cells, causes PML. To understand the molecular mechanism underlying immune regulation of JCV replication, we have developed a cell culture system and have investigated the effect of soluble factors from T-cell cultures on replication of JCV DNA in glial cells. Our data demonstrate that replication of JCV DNA in the presence of PMA-stimulated T-cell supernatant is substantially decreased in transfected glial cells. Heat-inactivation and size-fractionation studies revealed participation of a heat labile factor(s) which loses its maximum activity at 60 degrees and ranges between 30 and 100 kDa in size. The unfractionated T-cell supernatant and the fraction enriched in 30- to 100-kDa proteins reduced the level of viral DNA replication during the early phase of the lytic cycle. These observations suggest that regulatory factors which are secreted by immune cells may modulate the level of JCV DNA replication in glial cells. The importance of these observations in reactivation of JCV in immunocompromised individuals and development of PML is discussed.

Differential regulation of plasminogen activator and inhibitor gene transcription by the tumor suppressor p53

The ability of p53 to activate or repress transcription suggests that its biological function as tumor suppressor is in part accomplished by regulating a number of genes including such required for inhibition of cell growth. We here give evidence that p53 also may regulate genes responsible for the proteolytic degradation of the extracellular matrix, which is considered a crucial feature for local invasion and metastasis of neoplastic cells. An important and highly regulated cascade of such proteolytic events involves the plasminogen activator system. We show that wild-type p53 represses transcription from the enhancer and promoter of the human urokinase-type (u-PA) and the tissue-type plasminogen activator (t-PA) gene through a non-DNA binding mechanism. Oncogenic mutants lost the repressing activity. In contrast, wild-type but not mutant p53 specifically binds to and activates the promoter of the plasminogen activator inhibitor type-1 (PAI-1) gene. Interestingly, one of the p53 mutants (273his) inhibited PAI-1 promoter activity. Our results suggest that altered function of oncogenic forms of p53 may lead to altered expression of the plasminogen activators and their inhibitor(s) and thus to altered activation of the plasminogen/plasmin system during tumor progression.