Short communication: Effects of a commercial triple-strain Bacillus-based probiotic on cecal colonization with Salmonella Enteritidis in commercial layer pullets.

A commercial triple-strain Bacillus-based probiotic was tested to determine its effect on the colonization of the ceca by Salmonella Enteritidis (SE) in commercial layer pullets. Two treatments were tested, each with containing 128 day-of-hatch LSL layer chicks. On top of a standard diet: 1) no supplement (Control, CON), and 2) Probiotic (GalliPro® Fit, 500 g/MT, 1.6 × 106 CFU/g of finished feed, PRO). Environmental swabs were collected from each treatment group and tested to ensure freedom from SE prior to challenge. At 21 days of age, the SE challenge strain was administered orally at a dose of 3.3 × 108 CFU/bird. Pullets from each treatment group (n=32) were euthanized at 6-, 10-, 14-, and 18-days post infection (dpi). Contents from the ceca were aseptically collected and assessed for presence and abundance of SE. No differences in the prevalence of SE positive ceca following oral inoculation (P>0.05) were observed between treatment groups at 6-, 10-, 14-, or 18-dpi. Counts of SE in the ceca of the PRO group were not significantly different (P>0.05) from those of CON at 6- or 10-dpi. However, significantly lower counts of SE in the ceca of the PRO group were observed at 14-dpi (P<0.05) and 18-dpi (P<0.05) compared with CON. SE counts were 1.24 and 1.34 logs lower than CON at 14- and 18-dpi, respectively. In conclusion, supplementation of the triple-strain Bacillus-based probiotic resulted in lower cecal counts of SE compared to those that did not receive an effective probiotic, thereby reducing the risk of foodborne pathogens prior to harvest through sustainable, natural methods.

Double immunohistochemistry enhances detection of lymphatic and venous invasion in early-stage colorectal cancer.

Lymphatic invasion (LI) and venous invasion (VI) are regarded as important risk factors of nodal disease in early-stage colorectal cancer (CRC) but with variable reporting and poor distinction of these parameters in previous studies. This study examines the application of a double immunohistochemistry (D-IHC) method to help detect and distinguish LI and VI, in comparison with haematoxylin and eosin (H&E) staining, in a clinical series of cases of stage pT1 CRC. The aims were to demonstrate feasibility of this methodology in routine practice and compare rates of LI and VI reporting with and without D-IHC application. D-IHC utilising CAM5.2 with the endothelial marker CD34 and with the specific lymphatic endothelial marker D2-40 was performed on parallel sections from single representative paraffin tissue blocks in 28 cases of stage pT1 CRC from routine clinical practice. D-IHC significantly increased rates of both LI and VI reporting, from 14.3 to 35.7 % and from 14.3 to 28.6 %, respectively. The D-IHC methodology described is technically feasible in routine practice and potentially offers a more sensitive and robust assay for detection and distinction of LI and VI in early CRC pathology reporting. The reproducibility and clinical significance of enhanced LI and VI detection by this method and the relative importance of LI and VI in this clinical setting require further study.

Survey of congenital cytomegalovirus (cCMV) knowledge among medical students.

BACKGROUND: Congenital cytomegalovirus (cCMV) is a leading cause of congenital infection worldwide and the most common congenital infection in the United States, affecting 30,000-40,000 US newborns each year and causing permanent disabilities in 8000-10,000. In contrast to how commonly it occurs, physicians and medical students have little knowledge of cCMV. OBJECTIVES: To test the hypothesis medical students have little awareness about cCMV infection, and to collect data on medical students' knowledge about cCMV. The long-term goal of this project is to establish medical student awareness of cCMV infection and educate students about available treatments and strategies for prevention in at-risk populations. STUDY DESIGN: Medical students at one institution were surveyed by questionnaire to assess their knowledge of cCMV. Responses were described, quantified, and compared between groups. RESULTS: 751 surveys were sent and 422 completed responses were received. Respondents were well distributed over all 4 medical school (MS) class years. Only 34% MS1 had heard of cCMV compared to 100% MS2-4 (P<0.0001). All MS2-4 who reported being "very familiar" with CMV learned about it in medical school, 80% in one lecture. MS1 respondents were significantly less knowledgeable about cCMV than MS2-MS4 respondents. CONCLUSION: A baseline lack of knowledge about cCMV was documented in first year medical students. A sharp increase in knowledge of cCMV occurred between MS1 and MS2 years, likely due to preclinical medical student curriculum. However, significant knowledge gaps regarding transmission and treatment were observed in all MS years, representing opportunities for medical education.

Structural and mechanistic basis of Parl activity and regulation.

The mitochondrial rhomboid protease Parl governs apoptosis, morphology, metabolism and might be implicated in Parkinson's disease, but the structural basis of its activity and complex regulation remain unknown. We report the discovery of γ-cleavage, a proteolytic event on the loop connecting the first transmembrane helix (TMH) of Parl to the 6-TMH catalytic rhomboid domain of the protease. This cleavage disrupts the '1+6' structure that defines every mitochondrial rhomboid and generates a new form of Parl, PROD (Parl-rhomboid-domain). Structure-function analysis of Parl suggests that γ-cleavage could be implicated in eliminating Parl proteolytic activity, and structural modeling of PROD reveals structural conservation with the bacterial rhomboid GlpG. However, unlike bacterial rhomboids, which employ a diad-based mechanism of catalysis, Parl appears to use a conserved mitochondrial rhomboid-specific Asp residue on TMH-5 in a triad-based mechanism of catalysis. This work provides unexpected insights into the structural determinants regulating Parl stability and activity in vivo, and reveals a complex cascade of proteolytic events controlling the function of the protease in the mitochondrion.

Loss of the Parkinson's disease-linked gene DJ-1 perturbs mitochondrial dynamics.

Growing evidence highlights a role for mitochondrial dysfunction and oxidative stress as underlying contributors to Parkinson's disease (PD) pathogenesis. DJ-1 (PARK7) is a recently identified recessive familial PD gene. Its loss leads to increased susceptibility of neurons to oxidative stress and death. However, its mechanism of action is not fully understood. Presently, we report that DJ-1 deficiency in cell lines, cultured neurons, mouse brain and lymphoblast cells derived from DJ-1 patients display aberrant mitochondrial morphology. We also show that these DJ-1-dependent mitochondrial defects contribute to oxidative stress-induced sensitivity to cell death since reversal of this fragmented mitochondrial phenotype abrogates neuronal cell death. Reactive oxygen species (ROS) appear to play a critical role in the observed defects, as ROS scavengers rescue the phenotype and mitochondria isolated from DJ-1 deficient animals produce more ROS compared with control. Importantly, the aberrant mitochondrial phenotype can be rescued by the expression of Pink1 and Parkin, two PD-linked genes involved in regulating mitochondrial dynamics and quality control. Finally, we show that DJ-1 deficiency leads to altered autophagy in murine and human cells. Our findings define a mechanism by which the DJ-1-dependent mitochondrial defects contribute to the increased sensitivity to oxidative stress-induced cell death that has been previously reported.

Intestinal-type cervical adenocarcinoma in situ and adenocarcinoma exhibit a partial enteric immunophenotype with consistent expression of CDX2.

Most cases of cervical adenocarcinoma in situ (AIS) and adenocarcinoma are of the usual or endocervical type. However, intestinal types of AIS and adenocarcinoma exist. With an intestinal-type adenocarcinoma in the cervix, the question may arise as to whether one is dealing with a primary cervical neoplasm or direct or secondary spread from an intestinal adenocarcinoma. In organs such as the ovary, urinary bladder, esophagus, and gallbladder, intestinal-type glandular epithelium often expresses enteric markers, but this has hardly been studied in the cervix. The purpose of this study was to investigate whether intestinal-type AIS and adenocarcinoma in the cervix express enteric markers and to ascertain whether these antibodies are of value in the distinction from a metastatic intestinal adenocarcinoma. We compared the immunophenotype of these lesions with that of usual-type AIS and adenocarcinomain the cervix. Cases included were AIS of usual type (n = 6), primary cervical adenocarcinoma of usual type (n = 6), AIS of intestinal type (n = 21), primary cervical adenocarcinoma of intestinal type (n = 3), primary cervical adenocarcinoma with signet ring cells (n = 2), and colorectal adenocarcinoma involving the cervix (n = 5). All cases were stained with cytokeratin (CK) 7, CK20, monoclonal carcinoembryonic antigen (CEA), p16, and CDX2. Staining was categorized as negative, focally positive (<50% cells), or diffusely positive (50% or more cells). Usual-type AIS was always diffusely CK7 positive, typically diffusely CEA and p16 positive, and always CK20 negative. CDX2 was positive in 1 case. All usual cervical adenocarcinomas were diffusely CK7 and p16 positive, and all were immunoreactive with CEA. Five and 2 cases were CK20 and CDX2 positive, respectively. Intestinal-type AIS was diffusely CK7 positive (all cases) and typically CK20 negative and diffusely CEA and p16 positive. All but 1 case exhibited diffuse nuclear positivity with CDX2. In addition, usual-type AIS adjacent to intestinal type was CDX2 positive in 13 of 21 cases. The 3 cases of primary cervical intestinal-type adenocarcinoma were diffusely CK7 positive, focally or diffusely positive with CK20 and CDX2, and focally positive with CEA. One case was diffusely p16 positive, 1 focal and 1 negative. The foci of signet ring cells in the 2 primary cervical adenocarcinomas were diffusely CK7 and p16 positive and negative with CK20 and CDX2. Colorectal adenocarcinomas involving the cervix were typically diffusely positive with CK20, CEA, and CDX2; negative with CK7; and negative or focally positive with p16. Intestinal types of cervical AIS and adenocarcinoma exhibit a partial enteric immunophenotype, usually with diffuse expression of CDX2 and, in some cases, staining with CK20. They maintain their CK7 immunoreactivity and are usually p16 positive. Although there is immunophenotypic overlap, focal staining with CK20 together with diffuse CK7 and sometimes p16 positivity helps to distinguish intestinal types of cervical adenocarcinoma from involvement by a colorectal adenocarcinoma; CEA and CDX2 are of no value in this regard. CDX2 positivity in usual-type AIS adjacent to intestinal type and in occasional cases of pure usual-type AIS may be a reflection of early intestinal differentiation before this is morphologically apparent. Using a set of cases of AIS diagnosed in a single institution over a 7-year period (77 usual type; 13 intestinal type), intestinal type was more likely to be associated with early invasive adenocarcinoma than usual type (31% vs 17%), suggesting that intestinal differentiation may be a risk factor for invasion in premalignant cervical glandular lesions.

Uterine leiomyosarcomas are characterized by high p16, p53 and MIB1 expression in comparison with usual leiomyomas, leiomyoma variants and smooth muscle tumours of uncertain malignant potential.

AIMS: It has been suggested that p16 is overexpressed in uterine leiomyosarcomas in comparison with leiomyomas. In this study, p16 immunohistochemical expression was assessed in a variety of uterine smooth muscle tumours, including usual leiomyomas, leiomyoma variants, smooth muscle tumours of uncertain malignant potential (STUMPs) and leiomyosarcomas. The aim was to ascertain whether there are differences in p16 expression between these groups and whether p16 is of potential value in the assessment of problematic uterine smooth muscle neoplasms. p16 expression was also compared with that of p53 and MIB1. METHODS AND RESULTS: Cases of usual leiomyoma (n = 10), leiomyoma variants (n = 27), STUMP (n = 4) and leiomyosarcoma (n = 22) were subject to p16, p53 and MIB1 immunohistochemistry. For p16, cases were evaluated with respect to both staining distribution and intensity. There was a statistically significant difference in p16 distribution (P < 0.001) and intensity (P = 0.001) between leiomyosarcomas and the other groups. There was no difference in p16 expression between usual leiomyomas, leiomyoma variants and STUMPs. There were also statistically significant differences in p53 (P = 0.014) and MIB1 (P < 0.001) immunoreactivity between leiomyosarcomas and the other groups. CONCLUSIONS: p16 is overexpressed in uterine leiomyosarcomas compared with leiomyomas, benign leiomyoma variants and STUMPs, suggesting that p16 may be implicated in the pathogenesis of malignant uterine smooth muscle neoplasms. p16, in combination with p53 and MIB1, may be of value as an adjunct to morphological examination in the assessment of problematic uterine smooth muscle tumours, although further large-scale studies with follow-up are necessary to confirm this.

High-grade ovarian serous carcinoma exhibits significantly higher p16 expression than low-grade serous carcinoma and serous borderline tumour.

AIMS: A dualistic pathway of ovarian serous carcinogenesis is now well established whereby high-grade serous carcinoma and low-grade serous carcinoma represent two distinct tumour types with a different underlying pathogenesis. The aim of this study was to compare expression of p16 INK4A (p16) in these two tumour types. We also included cases of serous borderline tumour, since these are considered to represent a precursor lesion of low-grade serous carcinoma. METHODS AND RESULTS: Cases of serous borderline tumour (n = 18), low-grade ovarian serous carcinoma (n = 22) and high-grade ovarian serous carcinoma (n = 24) were stained with a monoclonal antibody against p16. Cases were scored both with respect to intensity of immunoreactivity (weak, 1+; moderate, 2+; or strong, 3+) and distribution (0, negative or occasional positive cells; 1+, < 10% cells positive; 2+, 10-25% cells positive; 3+, 26-50% cells positive; 4+, 51-75% cells positive; or 5+, 76-100% cells positive). An immunohistochemical composite score was also calculated (0-15) by multiplying the intensity and distribution scores. There was a statistically significant difference in p16 immunoreactivity with respect to intensity, distribution and composite score between high-grade serous carcinoma and each of the other two groups, with the high-grade neoplasms exhibiting stronger and more diffuse positivity. Most high-grade serous carcinomas exhibited positivity of close to 100% of tumour cells. There was no significant difference in p16 expression between the borderline tumours and low-grade serous carcinomas. CONCLUSIONS: The increased expression of p16 in high-grade serous carcinoma compared with low-grade serous carcinoma and serous borderline tumour is in keeping with a different underlying pathogenesis. p16 may be implicated in the development of high-grade serous neoplasia within the ovary and elsewhere within the female genital tract.

In vivo and in vitro examination of the functional significances of novel lamin gene mutations in heart failure patients.

CONTEXT: Lamin A/C (LMNA) gene variations have been reported in more than one third of genotyped families with dilated cardiomyopathy (DCM). However, the relationship between LMNA mutation and the development of DCM is poorly understood. METHODS AND RESULTS: We found that end stage DCM patients carrying LMNA mutations displayed either dramatic ultrastructural changes of the cardiomyocyte nucleus (D192G) or nonspecific changes (R541S). Overexpression of the D192G lamin C dramatically increased the size of intranuclear speckles and reduced their number. This phenotype was only partially reversed by coexpression of the D192G and wild type lamin C. Moreover, the D192G mutation precludes insertion of lamin C into the nuclear envelope when co-transfected with the D192G lamin A. By contrast, the R541S phenotype was entirely reversed by coexpression of the R541S and wild type lamin C. As lamin speckle size is known to be correlated with regulation of transcription, we assessed the SUMO1 distribution pattern in the presence of mutated lamin C and showed that D192G lamin C expression totally disrupts the SUMO1 pattern. CONCLUSION: Our in vivo and in vitro results question the relationship of causality between LMNA mutations and the development of heart failure in some DCM patients and therefore, the reliability of genetic counselling. However, LMNA mutations producing speckles result not only in nuclear envelope structural damage, but may also lead to the dysregulation of cellular functions controlled by sumoylation, such as transcription, chromosome organisation, and nuclear trafficking.

An immunohistochemical analysis of ovarian small cell carcinoma of hypercalcemic type.

Ovarian small cell carcinoma of hypercalcemic type (OSCCHT) is a rare neoplasm with an aggressive behavior, broad differential diagnosis, and unknown histogenesis. To add to knowledge concerning the possible aid of immunohistochemistry in resolving problems in differential diagnosis and to further explore whether that modality points to any specific histogenesis, we undertook an immunohistochemical study of this neoplasm. Fifteen OSCCHTs (including four of the ''large cell" variant) were stained with a range of antibodies, some of which have not been investigated previously in this neoplasm. Cases were stained with AE1/3, EMA, BerEP4, CK5/6, calretinin, WT1, chromogranin, CD56, synaptophysin, CD99, NB84, desmin, S100, CD10, alpha inhibin, TTFI, and p53. Staining was classified as 0 (negative), 1+ (<5% cells positive), 2+ (5% to 25% cells positive), 3+ (26% to 50% cells positive), or 4+ (>50% cells positive). All cases were positive with p53 (two 1+, five 3+, eight 4+), 14 of 15 cases were positive with WT1 (one 1+, thirteen 4+), 14 of 15 with CD10 (three 1+, four 2+, two 3+, five 4+), 13 of 15 with EMA (three 1+, three 2+, two 3+, five 4+), 11 of 15 with calretinin (nine 1+, one 3+, one 4+), 9 of 15 with AE1/3 (eight 1+, one 2+), 4 of 15 with CD56 (one 1+, two 2+, one 4+), 3 of 15 with BerEP4 (two 2+, one 4+), 2 of 15 with synaptophysin (two 1+), and 1 of 15 with S100 (4+). All cases were negative with CK5/6, chromogranin, CD99, NB84, desmin, alpha inhibin, and TTF1. The only noticeable difference in the immunophenotype between typical OSCCHT and the large cell variant was that there was 4 +EMA positivity in three of four cases of large cell variant compared with two of 11 cases of typical OSCCHT. OSCCHT is characteristically positive with AE1/3, EMA, CD10, calretinin, WT1, and p53. Combined EMA and WT1 positivity, the latter usually intense and diffuse, may be of diagnostic value, inasmuch as only a few of the neoplasms in the differential diagnosis are positive with both antibodies. Negative staining with CD99, desmin, NB84, alpha-inhibin, and TTF1 may aid in the cases in which primitive neuroectodermal tumor, rhabdomyosarcoma, intraabdominal desmoplastic small round cell tumor, neuroblastoma, a sex cord-stromal tumor, and metastatic pulmonary small cell carcinoma are in the differential. Calretinin positivity precludes its use in the differential with granulosa cell tumors. The results of this investigation do not settle the issue of histogenesis, which remains enigmatic. The typical age distribution, follicle formation, and calretinin positivity are consistent with a sex cord origin. On the other hand, WT1 and EMA positivity and negative staining with alpha-inhibin would be unusual in a sex cord-stromal neoplasm and can be used as an argument for a surface epithelial origin. Germ cell and neuroendocrine origins seem highly unlikely.

Cytomegalovirus infection of the cervix: morphological observations in five cases of a possibly under-recognised condition.

AIMS: Histologically diagnosed cytomegalovirus (CMV) infection of the cervix is rare and the associated morphological features are not well described. This study describes histopathological findings in five biopsies from four patients with CMV cervicitis. METHODS: CMV inclusions were identified in five cervical biopsies from four patients in a single institution over eight months. The clinical notes were reviewed, the morphological features documented, and immunohistochemical staining for CMV performed. CMV immunohistochemical staining was also performed on 30 consecutive cervical biopsies in which inclusions were not seen histologically. RESULTS: None of the patients was immunocompromised but one was postnatal. Numbers of CMV inclusions ranged from occasional to abundant and they were located mainly in endocervical glandular epithelial cells but also in endothelial and mesenchymal cells. Inclusions were not seen in squamous cells. Inclusions were eosinophilic and were intracytoplasmic rather than intranuclear. They were positive immunohistochemically for CMV. Associated morphological features included fibrin thrombi within small blood vessels (three cases), dense active inflammatory infiltrates (five cases), lymphoid follicles (two cases), vacuolation of glandular epithelial cells (two cases), and reactive changes in glandular epithelial cells (two cases). CMV inclusions were not identified in the 30 additional cases that underwent immunohistochemical staining. CONCLUSIONS: CMV infection of the cervix may be more common than is thought. Patients are usually immunocompetent and require no treatment. Morphological features such as a dense inflammatory cell infiltrate with lymphoid follicles, and especially fibrin thrombi within small vessels, should alert the pathologist to look closely for the pathognomonic CMV inclusion bodies.

CD10 and calretinin staining of endocervical glandular lesions, endocervical stroma and endometrioid adenocarcinomas of the uterine corpus: CD10 positivity is characteristic of, but not specific for, mesonephric lesions and is not specific for endometrial stroma.

AIMS: In the female genital tract CD10 has been used to assist in the evaluation of mesenchymal tumours of the uterus and in determining whether endometrial stroma is present. CD10 positivity has also been shown in cervical mesonephric remnants and this antibody has been suggested as a useful immunohistochemical marker of mesonephric lesions in the female genital tract. Calretinin has also been shown to be positive in mesonephric lesions. In this study the specificity of these two antibodies in evaluating cervical and uterine glandular lesions and the value of CD10 in determining whether stroma is endometriotic or not were investigated. METHODS AND RESULTS: Cases of cervical tubo-endometrial metaplasia (TEM) (n = 11), microglandular hyperplasia (MGH) (n = 10), endometriosis (n = 8), mesonephric remnants/hyperplasia (n = 12), endocervical adenocarcinoma, usual type (n = 15), mucinous variant of minimal deviation adenocarcinoma (MDA) (n = 7) and mesonephric adenocarcinoma (n = 3) were stained with antibodies against CD10 and calretinin. Nine cases of endometrial adenocarcinoma of endometrioid type were also stained. In all the cervical cases normal endocervical glands were negative with both antibodies except for one case with strong positive luminal staining with CD10. All cases of TEM, MGH and endometriosis were negative with CD10 and calretinin except for focal staining with CD10 in one case each of MGH (cytoplasmic staining) and endometriosis (luminal staining). Most usual endocervical adenocarcinomas were negative with both antibodies, although one exhibited focal cytoplasmic staining with calretinin and five exhibited limited luminal positivity with CD10. All MDAs were negative with both antibodies. Ten of 12 mesonephric remnants/hyperplasia showed luminal positivity with CD10 and one exhibited cytoplasmic and nuclear staining with calretinin. Two of three mesonephric adenocarcinomas showed luminal positivity with CD10 and nuclear and cytoplasmic positivity with calretinin. Seven of nine endometrial adenocarcinomas were positive with CD10 (four cytoplasmic, two membranous and cytoplasmic, one luminal and cytoplasmic) and three with calretinin (two cytoplasmic, one nuclear and cytoplasmic). Positive staining of endometriotic stroma with CD10 was present in all endometriosis cases but normal cervical stroma was also strongly positive, especially around glands. Endometriotic stroma and cervical stroma were negative with calretinin. CONCLUSIONS: We conclude that most endocervical glandular lesions, including mesonephric remnants/ hyperplasia, are negative with calretinin. However, the focal nuclear and cytoplasmic positivity with calretinin in two of three mesonephric adenocarcinomas suggests that this may be a useful indicator of a mesonephric origin of a cervical adenocarcinoma. Most mesonephric remnants/hyperplasias exhibit luminal positivity with CD10, although this is not invariable and staining is usually focal. Positive luminal staining of a benign endocervical glandular lesion with CD10 may help confirm mesonephric remnants. Although positive staining with CD10 was found in two of three mesonephric adenocarcinomas, the observed immunoreactivity of several conventional cervical adenocarcinomas limits the diagnostic value of CD10 in confirming a mesonephric origin for an adenocarcinoma. Since all cervical MDAs were negative with CD10, positivity with this antibody may be of value in distinguishing mesonephric hyperplasia from MDA, although this distinction rarely necessitates immunohistochemistry. Most endometrial adenocarcinomas of endometrioid type stain with CD10 and thus positivity with this antibody is not specific for a mesonephric origin of an endometrial adenocarcinoma. Positivity of normal cervical stroma limits the value of CD10 staining in confirming a diagnosis of cervical endometriosis.

Immunohistochemical expression of CD10 and t(14;18) chromosomal translocation may be indicators of follicle centre cell origin in nodal diffuse large B-cell lymphoma.

AIMS: Although diffuse large B-cell lymphoma is categorized as a distinct entity in the REAL classification of lymphomas, it represents a heterogeneous group of neoplasms. A subgroup is probably of follicle centre cell origin and may evolve from a pre-existing follicular lymphoma. The t(14;18) chromosomal translocation can be demonstrated in the majority of follicular lymphomas and the aim of this study was to investigate the prevalence of t(14;18) translocation in a series of de novo nodal diffuse large B-cell lymphomas. We correlated this with the immunohistochemical expression of CD10, bcl2 and bcl6, markers which are usually expressed by the neoplastic cells in follicular lymphomas. We also correlated these parameters with the presence or absence of p53 protein expression by the neoplastic cells. METHODS AND RESULTS: Nodal diffuse large B-cell lymphomas (n=34) were stained immunohistochemically with monoclonal antibodies to CD10, bcl2, bcl6 and p53 (D07). Polymerase chain reaction (PCR) for the t(14;18) translocation was also performed. Fourteen, 24 and 29 (41%, 71%, 85%) cases exhibited positivity for CD10, bcl2 and bcl6, respectively. In 12 cases there was positivity with D07 (35%). By PCR, the t(14;18) translocation was identified in five cases (15%), four of which were positive for CD10 and bcl2 and all of which were positive for bcl6. One of five cases positive for the chromosomal translocation exhibited positivity with D07. CONCLUSIONS: In this study the t(14;18) translocation was identified in 15% of diffuse large B-cell lymphomas, all but one of which exhibited positivity for CD10, bcl2 and bcl6. These may represent cases of follicle centre cell origin which may or may not have evolved from a pre-existing follicular lymphoma. It is possible that positivity for CD10 especially may identify cases which are of follicle centre cell origin and that the absence of t(14;18) translocation in some of these cases may reflect the fact that the translocation cannot normally be demonstrated in all follicular lymphomas. Whether the presence or absence of the translocation and the immunophenotype are prognostically important should be investigated further.

The protein kinase Pho85 is required for asymmetric accumulation of the Ash1 protein in Saccharomyces cerevisiae.

The Ash1 protein is a daughter cell-specific repressor of HO gene transcription in Saccharomyces cerevisiae. Both ASH1 mRNA and protein are localized to the incipient daughter cell at the end of mitosis; Ash1 then inhibits HO transcription in the daughter cell after cytokinesis. Mother cells, in contrast, contain little or no Ash1 and thus are able to transcribe HO. We show that deletion of PHO85, which encodes a cyclin-dependent protein kinase, causes reduced transcription of HO and that this reduction is dependent on ASH1. In pho85 mutants, Ash1 protein is no longer asymmetrically localized and is present, instead, in both mother and daughter cells. Initially, it appears to be localized properly but then persists as daughter cells mature into mother cells. In contrast, ASH1 mRNA is localized appropriately to daughter cells in pho85 mutants. We observe that Ash1 protein is phosphorylated by Pho85 in vitro and that Ash1 stability increases in a pho85 mutant. These data suggest that phosphorylation of Ash1 by Pho85 governs stability of Ash1 protein.

Rab proteins as membrane organizers.

Cellular organelles in the exocytic and endocytic pathways have a distinctive spatial distribution and communicate through an elaborate system of vesiculo-tubular transport. Rab proteins and their effectors coordinate consecutive stages of transport, such as vesicle formation, vesicle and organelle motility, and tethering of vesicles to their target compartment. These molecules are highly compartmentalized in organelle membranes, making them excellent candidates for determining transport specificity and organelle identity.

The central matrix loop drives import of uncoupling protein 1 into mitochondria.

The uncoupling protein (UCP1) is a carrier protein of the inner mitochondrial membrane spanning the bilayer six times. It does not contain a typical amino-terminal targeting signal and the mechanism of targeting and insertion is unknown. Here we focus on the biogenesis of UCP1 by analysing the import signals contained within the three repeated units of the protein. The amino-terminal third of the protein can mediate insertion into the outer membrane and therefore acts as artificial targeting signal when fused to DHFR. However, in the context of full-length UCP, the targeting information contained within the first repeated unit is not sufficient to trigger insertion into the outer membrane. Deletion of either the first or third repeated unit from UCP1 did not reduce import into the inner membrane and bound to the outer membrane receptor protein hTom20 with the characteristics of full-length UCP1. Deletion of the second repeat of UCP1 completely abolished all import into the mitochondria. Consistent with this, the central repeat alone was efficiently imported to the inner membrane and bound hTom20 with the characteristics of UCP1. We conclude that the site for binding hTom20 is within the central repeat and that this domain contains the complete targeting signal for directing UCP1 to the inner membrane.

Degradation of the transcription factor Gcn4 requires the kinase Pho85 and the SCF(CDC4) ubiquitin-ligase complex.

Gcn4, a yeast transcriptional activator that promotes the expression of amino acid and purine biosynthesis genes, is rapidly degraded in rich medium. Here we report that SCF(CDC4), a recently characterized protein complex that acts in conjunction with the ubiquitin-conjugating enzyme Cdc34 to degrade cell cycle regulators, is also necessary for the degradation of the transcription factor Gcn4. Degradation of Gcn4 occurs throughout the cell cycle, whereas degradation of the known cell cycle substrates of Cdc34/SCF(CDC4) is cell cycle regulated. Gcn4 ubiquitination and degradation are regulated by starvation for amino acids, whereas the degradation of the cell cycle substrates of Cdc34/SCF(CDC4) is unaffected by starvation. We further show that unlike the cell cycle substrates of Cdc34/SCF(CDC4), which require phosphorylation by the kinase Cdc28, Gcn4 degradation requires the kinase Pho85. We identify the critical target site of Pho85 on Gcn4; a mutation of this site stabilizes the protein. A specific Pho85-Pcl complex that is able to phosphorylate Gcn4 on that site is inactive under conditions under which Gcn4 is stable. Thus, Cdc34/SCF(CDC4) activity is constitutive, and regulation of the stability of its various substrates occurs at the level of their phosphorylation.

Interactions between Pho85 cyclin-dependent kinase complexes and the Swi5 transcription factor in budding yeast.

Pho85 is a cyclin-dependent protein kinase (Cdk) in budding yeast with roles in cell metabolism and cell cycle progression. Activation of Pho85 occurs through association with Pho85 cyclins (Pcls), of which 10 are known. When complexed with the G1 cyclins, Pcl1 and Pcl2, Pho85 is required for cell cycle progression in the absence of the Cdc28-dependent cyclins, Cln1 and Cln2. To identify potential targets of Pcl2-Pho85, we performed a two-hybrid screen using the Pcl2 cyclin as bait and recovered the transcription factor Swi5 as a Pcl2-interacting protein. We performed both biochemical and genetic tests to discover the biological significance of the interaction between Pcl2 and Swi5 seen in the two-hybrid assay. We found that Swi5 interacts in vitro with Pho85 cyclins and is phosphorylated in vitro by the Pho80-Pho85 kinase. We discovered that a subset of genes that are controlled by Swi5 and a homologous transcription factor, Ace2, was misregulated in a pho85 deletion strain; expression of the ASH1 and CTS1 genes was reduced in an ace2 deletion strain, whereas expression of both genes was increased in an ace2Delta pho85Delta double mutant. We also found that overexpression of SWI5 caused cell lethality in a pho85 deletion strain. Our results are consistent with misregulation of Swi5 activity in vivo in the absence of Pho85 and implicate Swi5 as a potential substrate of Pho85 cyclin-dependent kinase complexes.

Oligomeric complexes link Rab5 effectors with NSF and drive membrane fusion via interactions between EEA1 and syntaxin 13.

SNAREs and Rab GTPases cooperate in vesicle transport through a mechanism yet poorly understood. We now demonstrate that the Rab5 effectors EEA1 and Rabaptin-5/Rabex-5 exist on the membrane in high molecular weight oligomers, which also contain NSF. Oligomeric assembly is modulated by the ATPase activity of NSF. Syntaxin 13, the t-SNARE required for endosome fusion, is transiently incorporated into the large oligomers via direct interactions with EEA1. This interaction is required to drive fusion, since both dominant-negative EEA1 and synthetic peptides encoding the FYVE Zn2+ finger hinder the interaction and block fusion. We propose a novel mechanism whereby oligomeric EEA1 and NSF mediate the local activation of syntaxin 13 upon membrane tethering and, by analogy with viral fusion proteins, coordinate the assembly of a fusion pore.

Distinct regions of the Swi5 and Ace2 transcription factors are required for specific gene activation.

Swi5 and Ace2 are cell cycle-regulated transcription factors that activate expression of early G(1)-specific genes in Saccharomyces cerevisiae. Swi5 and Ace2 have zinc finger DNA-binding domains that are highly conserved, and the two proteins bind to the same DNA sequences in vitro. Despite this similarity in DNA binding, Swi5 and Ace2 activate different genes in vivo, with Swi5 activating the HO gene and Ace2 activating CTS1 expression. In this report we have used chimeric fusions between Swi5 and Ace2 to determine what regions of these proteins are necessary for promoter-specific activation of HO and CTS1. We have identified specific regions of Swi5 and Ace2 that are required for activation of HO and CTS1, respectively. The Swi5 protein binds HO promoter DNA cooperatively with the Pho2 homeodomain protein, and the HO specificity region of Swi5 identified in the chimeric analysis coincides with the region of Swi5 previously identified that interacts with Pho2 in vitro. Swi5 and Ace2 also activate expression of a number of other genes expressed in G(1) phase of the cell cycle, including ASH1, CDC6, EGT2, PCL2, PCL9, RME1, and SIC1. Analysis of the Swi5/Ace2 chimeras shows that distinct regions of Swi5 and Ace2 contribute to the transcriptional activation of some of these other G(1)-regulated genes.