Basal Pole Of Cells Research Articles

Rare Inherited Cholestatic Disorders and Molecular Links to Hepatocarcinogenesis

Hepatocellular carcinoma (HCC) is the most common primary liver cancer affecting adults and the second most common primary liver cancer affecting children. Recent years have seen a significant increase in our understanding of the molecular changes associated with HCC. However, HCC is a complex disease, and its molecular pathogenesis, which likely varies by aetiology, remains to be fully elucidated. Interestingly, some inherited cholestatic disorders that manifest in childhood are associated with early HCC development. This review will thus explore how three genes that are associated with liver disease in childhood (ABCB11, TJP2 and VPS33B) might play a role in the initiation and progression of HCC. Specifically, chronic bile-induced damage (caused by ABCB11 changes), disruption of intercellular junction formation (caused by TJP2 changes) and loss of normal apical–basal cell polarity (caused by VPS33B changes) will be discussed as possible mechanisms for HCC development.

Histological features of differentiated dysplasia in the oral mucosa: a review of oral invasive squamous cell carcinoma cases diagnosed with benign or low-grade dysplasia on previous biopsies

The diagnosis of oral squamous cell carcinoma is sometimes delayed. Recently, the concept of differentiated dysplasia in the oral mucosa was proposed, and we attempted to elucidate the histologic features of differentiated dysplasia in the oral mucosa. Two pathologists reviewed 38 small biopsy cases of patients diagnosed with benign to low-grade dysplasia in the first biopsy, but were diagnosed with invasive carcinoma after excisional biopsy within 2 years. Of these, 29 cases were suspected of having differentiated dysplasia, which histologically showed "abnormal variation in nuclear size and shape,""increased number and size of nucleoli,"and "loss of polarity of basal cells."In addition to the features observed in classic dysplasia, "premature keratinization in single cells" and "loss of epithelial cell cohesion" were characteristically observed. These 2 findings were often observed only in the lower half of the epithelium, but not in the full layer of the epithelium. Histological findings of oral differentiated dysplasia were very similar to those of differentiated vulvar intraepithelial neoplasia. "Premature keratinization in single cells" and "loss of epithelial cell cohesion" are specific pathological findings of oral differentiated dysplasia. Oral differentiated dysplasia is considered as a part of the broad spectrum of oral dysplasia that exhibits morphological characteristics different from classic dysplasia rather than being a separate entity. The diagnosis of oral differentiated dysplasia is expected to reduce the delayed diagnosis and improve the prognosis and post-treatment quality of life of patients with oral cavity cancer.

“Loss of polarity of basal cells” – The term revisited in the light of genomics

The concept of polarity in development, homeostasis and pathological alteration of tissues has emerged as an interesting aspect of the concerned biology. The epithelial cells exhibit apicobasal polarity which is maintained by Crumbs complex located at apical region of tight junction, ‘PAR’ complex at sub-apical region of tight junction and Scribble complex at adherens junction. Any functional perturbation of these proteins cause alteration of normal epithelial physiology en-route to epithelial pathology. In this maiden scientific exercise, we have tried to explore the association of expression of cell polarity proteins in OPMD and OSCC. Here, we have chosen DLG1 as a representative of polarity protein. RNA was isolated from the tissue samples. Then cDNA was prepared by RTPCR technique. qPCR was performed on cDNA samples. Expression data was analysed on the basis of Ct values. Paired t-test was performed with normalized Ct values of disease and normal tissue to determine whether there was any significant difference in expression between them. The statistical tests were done using SPSS software. Results of this study reflected increase in DLG1 expression in high grade dysplasia. There was no significant alteration in expression of DLG1 in WDSCC where there is formation of cluster of neoplastic cells ultimately producing epithelial islands and keratin pearls. But, in case of MDSCC, when the same neoplastic cells keep on invading with minimal keratin pearl formation, they again gain the mesenchymal character in full potential. And this phenomenon supports the upregulation of DLG1 in MDSCC in our study.

DOES ORAL EPITHELIAL DYSPLASIA CRITERIA HOLD TRUE FOR DYSPLASTIC EPITHELIUM OF ORAL SUBMUCOUS FIBROSIS?

<h3>Background</h3> Oral submucous fibrosis (OSMF) is an oral potentially malignant disorder (OPMD) with an appearance of epithelium from hyperplastic to atrophic depending on the histopathologic staging. Oral epithelial dysplasia (OED) grading is done in OPMD, but it is difficult to grade every architectural and cytologic features when epithelium is atrophic. <h3>Objective</h3> To assess the OED features in OSMF and to compare with those in dysplastic epithelial margins of OSMF with concomitant oral squamous cell carcinoma (OSCC). <h3>Methods</h3> Histopathologic staging of 39 cases was done by the Pindborg and Sirsat system, and OED features were evaluated by the World Health Organization (WHO) grading system and the binary system. The statistical software SPSS 22.0 was used for the descriptive and inferential analysis. <h3>Results</h3> Sixteen cases were diagnosed as OSMF without dysplasia (group 1), 16 cases had dysplasia (group 2), and 7 cases had concomitant oral squamous cell carcinoma (group 3). All the cases (100%) in group 2 and group 3 showed architectural features like irregular epithelial stratification, loss of polarity of basal cells, and cellular features like nuclear- cytoplasmic pleomorphism and altered ratio. Premature keratinization was seen in group 2 (62.5%) and group 3 (85.7%). However, keratin pearl was seen only in group 3 (28.6%). Presence of increased size and number of nucleoli had a significant value (<i>P</i> < .017). <h3>Conclusions</h3> Some of the features of OED are not discernable, however some have striking presence in OSMF. It is not possible to use the WHO system in all cases, rather the binary system can be used with modification of criteria relevant to OSMF.

Clinicopathological features of basal cell type dysplasia of esophagus

Objective: To investigate the clinicpathological features of basal cell type dysplasia of the esophagus. Methods: The clinicopathological data of 71 cases of basal cell type dysplasia of esophagus were collected at the People's Liberation Army Joint Logistics Support Force 989 Hospital, from 2009 to 2019, and the histomorphologic characteristics and immunophenotype were evaluated. The relevant literature was reviewed. Results: The ratio of male to female patients was 1.6∶1.0, and the median age was 65 years (range 48-81 years). The tumors were located in the upper segment of the esophagus in four cases (5.6%), the middle segment in 54 cases (76.1%), and the lower segment in 13 cases (18.3%).The median maximal tumor diameter was 12.0 mm (range 3-42 mm). According to Paris Classification, 0-Ⅱb accounted for 42.3% (30/71) of the cases. Under endoscope, the lesions were reddish with abnormal mucosal microvessels. Histologically, the neoplastic cells were small, with a high nuclear-cytoplasmic ratio, similar to basal cells, and uniform in morphology. The structural atypia was characterized by dense and disordered tumor cells, loss of basal cell polarity, and absence of normal squamous differentiation gradient. In 10 cases, the tumors were confined to the lower part of the epithelium. The tumor cells were smaller and more uniform in shape, and extend to the superficial lamina propria. Sixty-one tumors involved at least the entire layer of the upper cortex. There were 31 cases of neoplasms with superficial invasive carcinoma. The types of neoplasms included typical squamous cell carcinoma, basaloid squamous cell carcinoma, small cell neuroendocrine carcinoma, squamous cell carcinoma with sebaceous adenoid carcinoma, and differentiation of glandular/ductal epithelioid carcinoma. Immunohistochemical staining showed that the mutant expression rate of p53 protein was 41.5% (17/41). All 41 cases (100.0%) showed abnormal distribution pattern of Ki-67. According to the initial pathologic diagnosis, there were 18 cases of low grade dysplasia, 12 cases of atypical epithelial cells, and 41 cases of high grade dysplasia and superficially invasive carcinoma. Conclusions: Basal cell type dysplasia has unique morphologic characteristics and represents a tumor subtype in the morphologic lineage of esophageal squamous dysplasia. Tumor cells of basal cell type dysplasia, especially those distributed only in the lower part of the stratified squamous epithelium, may be tumor stem cells at the earliest stage of esophageal carcinogenesis and have multidirectional differentiation potential. When the tumor is confined to the lower part of the stratified squamous epithelium, it does not meet the diagnostic criteria for esophageal squamous dysplasia as defined by the current WHO classification.

Epithelial Dysplasia in Actinic Cheilitis: Microscopic Study of 70 Cases from Brazil.

To compare two grading systems of epithelial dysplasia-World Health Organization (WHO) and binary system (BS) -in actinic cheilitis (AC). Seventy cases diagnosed as AC in an Oral Pathology Laboratory from Brazil in the last 12years were retrospectively retrieved, including the demographic data of each patient. All conventionally stained slides were reviewed, and epithelial dysplasia was evaluated by two independent observers using both WHO and BS grading systems. Data correlation was performed using kappa and chi-square tests (p < 0.05). Most patients were white men with a mean age of 57years old and history of chronic exposure to sunlight. Most of the lesions were clinically described as whitish plaques with irregular surface located in the lower lip semi-mucosa. Most cases were microscopically graded as severe epithelial dysplasia and low-risk by both observers. The interobserver and intraobserver agreement between systems was slight. All reddish lesions were graded as severe epithelial dysplasia, showing an equal distribution between low and high-risk grading. Most ulcerated lesions showed severe epithelial dysplasia but was graded as low-risk of malignant transformation. Statistical significance was observed among the presence of "irregular stratification", severe epithelial dysplasia and high-risk lesions (p < 0.05) likewise among the presence of "loss of polarity of basal cells" and "drop-shaped ridges" (p < 0.05) with high-risk lesions. The absence of "increased mitotic figures", "dyskeratosis" and "keratin pearls" (p < 0.05) were strongly correlated to low-risk lesions. The presence of "hyperchromasia" was statistically significant with severe epithelial dysplasia (p < 0.05) as well the absence of "atypical mitotic figures" with low-risk lesions (p < 0.05). Although there was slight agreement between microscopic grading systems, microscopic analysis indicated that architectural epithelial changes individually may be the more reliable criteria to indicate the risk of malignant transformation in AC in both grading systems.

Exposure of Human Skin Organoids to Low Genotoxic Stress Can Promote Epithelial-to-Mesenchymal Transition in Regenerating Keratinocyte Precursor Cells.

For the general population, medical diagnosis is a major cause of exposure to low genotoxic stress, as various imaging techniques deliver low doses of ionizing radiation. Our study investigated the consequences of low genotoxic stress on a keratinocyte precursor fraction that includes stem and progenitor cells, which are at risk for carcinoma development. Human skin organoids were bioengineered according to a clinically-relevant model, exposed to a single 50 mGy dose of γ rays, and then xeno-transplanted in nude mice to follow full epidermis generation in an in vivo context. Twenty days post-xenografting, mature skin grafts were sampled and analyzed by semi-quantitative immuno-histochemical methods. Pre-transplantation exposure to 50 mGy of immature human skin organoids did not compromise engraftment, but half of xenografts generated from irradiated precursors exhibited areas displaying focal dysplasia, originating from the basal layer of the epidermis. Characteristics of epithelial-to-mesenchymal transition (EMT) were documented in these dysplastic areas, including loss of basal cell polarity and cohesiveness, epithelial marker decreases, ectopic expression of the mesenchymal marker α-SMA and expression of the EMT promoter ZEB1. Taken together, these data show that a very low level of radiative stress in regenerating keratinocyte stem and precursor cells can induce a micro-environment that may constitute a favorable context for long-term carcinogenesis.

The Carcinogenic Potential of Cadmium in Gingival Epithelium of Rats (Histological and Immunohistochemical Study)

Cadmium is a toxic, heavy industrial metal that causes serious environmental health hazards. Cadmium containing compounds have been classified as known human carcinogens and epidemiological data show causal associations to different types of cancers. This study designed to assess the carcinogenic effects of Cadmium on the gingival tissue of rats. Material and methods; Sixteen male albino Rats (age: 8 to 10 weeks and about 150 to 180 g body weight) from Animal Center of Faculty of Medicine, Mansoura University. The animals were divided into two equal groups, group I (control) and group II (cadmium chloride) rats were given 2 ml dose of a solution containing 10 mg/kg body weight of monohydrated cadmium chloride orally by gavage needle for 24 days. By the end of experiments, gingival epithelium around the teeth were carefully dissected, processed and stained using Haematoxyline & Eosin and immunohistochemical evaluation by iNOS. Statistical analysis was done to observe the statistical significant differences between the Cd group and control group in relation to dysplastic changes and iNOS immunoreaction. Results: the gingival tissue of Cd group revealed several dysplastic changes as, drop shape rete pegs, loss of polarity of basal cells, nuclear hyperchromatism, pleomorphism and increased mitotic pattern. a statistical significant difference regarding iNOS immunoreaction was found between control group and Cd group. conclusion to this study Cadmium chloride at low concentration and longtime of exposure can cause dysplastic changes in gingival tissue of rats.

Epidermal structure and differentiation.

In this Primer, Moreci and Lechler follow the lifetime of an epidermal cell from its birth to its ultimate death, and detail how this journey is necessary for epidermal function.

Immunohistochemical Evaluation of Bcl-2 and Ki-67 in Buccal Mucosa of Induced- Immunosuppressed Albino Rats

Introduction: Organ transplantation provides life-saving therapy for patients with end-organ disease. Tacrolimus is an immunosuppressive drug used to lower the risk of organ rejection. This study was performed to investigate the immunohistochemical expressions of Ki-67 (a proliferation associated antigen) and Bcl-2 (antiapoptotic protein) and their correlation with the increased risk of development of neoplasms in the buccal mucosa of tacrolimus-induced immunosuppressed albino rats. Material & methods: Twenty adult male albino rats were divided into two equal groups. Group one treated with tacrolimus in a daily oral dose 0.5 mg/kg for 3 months. Group two served as negative control, received distilled water in comparable volume. Tissue samples were fixed in 10% formalin, embedded in paraffin, and stained with hematoxylin and eosin to evaluate histopathological finding. Other sections were used to reveal the immunohistochemical expression of Ki-67 and Bcl-2 antibodies through computerized image j analysis software. The expression of both markers was analyzed statistically through using Mann-Whitney test. Results: Histopathological finding showed moderate dysplasia in tacrolimus-treated group. There was marked increase in normal mitotic figures, basal cell hyperplasia, loss of basal cell polarity, swirling of the spinous layer, prominent nucleoli, hyperchromatism, and altered N/C ratio. Immunohistochemical finding revealed marked increase in the nuclear expression of Ki-67 in basal cells and cytoplasmic expression of Bcl-2 in all layers of keratinocytes in tacrolimus-treated group. Statistical finding in tacrolimus – treated group showed significant difference in the expression of Ki-67 and highly significant difference in the expression of Bcl-2. Conclusion: There is an obvious relation between prolonged systemic use of tacrolimus and development of premalignant lesions. The marked increase in Ki-67 and Bcl-2 expression may play a role in tumorgenesis.

Dysplastic features relevant to malignant transformation in atrophic epithelium of oral submucous fibrosis: A preliminary study.

The grading of oral epithelial dysplasia (OED) is not applicable to oral submucous fibrosis (OSMF) cases due to the presence of atrophic epithelium. The mucosal margins associated with resected OSCC specimens are often closely related to transformed cells. In this study, we compared the histomorphological alterations (dysplastic features) in the atrophic epithelium of OSMF patients with the mucosal margins of OSCC associated with OSMF (OSCC-OSMF). We evaluated 17 dysplastic features in 37 patients with OSMF (biopsy site: buccal mucosa) and 37 patients with OSCC-OSMF (mucosal margins involving buccal mucosa) using histopathological staining. Dysplastic features, such as keratin pearls within rete ridges, nuclear pleomorphism, and atypical mitotic figures, were not observed in the epithelium of the OSMF or OSCC-OSMF groups. Basal cell hyperplasia (P=.016), abnormal superficial mitosis (P=.010), increased nuclear-cytoplasmic ratio (P=.034), and hyperchromasia (P=.031) were predominantly seen in the OSCC-OSMF group. We found no statistically significant differences in the following parameters: irregular epithelial stratification (P=1.00), loss of basal cell polarity (P=.237), presence of drop-shaped rete ridges (P=.077), increased number of mitotic figures (P=.154), premature keratinization in single cells (P=.499), anisonucleosis (P=.289), anisocytosis (P=.079), cellular pleomorphism (P=.317), and increased number and size of nucleoli (P=.129). Increased basal cell layer hyperplasia, abnormal superficial mitosis, increased nuclear-cytoplasmic ratio, and hyperchromasia are high-risk features for OSMF, and affected patients should be followed on a priority basis for the early detection of OSCC.

Morphodifferentiation of Gené’s organ in engorged Amblyomma sculptum Berlese, 1888 female ticks (Acari: Ixodidae)

The Gené’s organ (GO) secretes a waxy substance on eggs that reduces water loss and has antimicrobial properties. The current study evaluated morphological and histochemical aspects of GO in Amblyomma sculptum from the period of post-feeding – when ticks detach from the host – to the stage just before oviposition. In this species, GO is composed of a corpus and two pairs of glands, namely, cranial and caudal. Glandular cells are joined laterally by a system of interdigitating membranes with junctional complexes. Histochemistry showed that lipid droplets became more evident as GO developed, while glycogen gradually disappeared, and proteins were detected only near the onset of oviposition. The ultrastructural results revealed a marked distension of the cuticle filled with an amorphous material. Glandular cells showed poor endoplasmatic reticulum, many mitochondria mainly in the basal cell poles and a very developed basal labyrinth. We concluded that the development of GO in A. sculptum ticks was continuous and progressive, and it started after detachment from the host. Additionally, the ultrastructure study suggests that gland cells have an important absorption ability and a low synthetic activity, which indicates that the majority of wax precursors are derived from haemolymph.

Exposure to Carbon Ions Triggers Proinflammatory Signals and Changes in Homeostasis and Epidermal Tissue Organization to a Similar Extent as Photons.

The increasing application of charged particles in radiotherapy requires a deeper understanding of early and late side effects occurring in skin, which is exposed in all radiation treatments. We measured cellular and molecular changes related to the early inflammatory response of human skin irradiated with carbon ions, in particular cell death induction and changes in differentiation and proliferation of epidermal cells during the first days after exposure. Model systems for human skin from healthy donors of different complexity, i.e., keratinocytes, coculture of skin cells, 3D skin equivalents, and skin explants, were used to investigate the alterations induced by carbon ions (spread-out Bragg peak, dose-averaged LET 100 keV/μm) in comparison to X-ray and UV-B exposure. After exposure to ionizing radiation, in none of the model systems, apoptosis/necrosis was observed. Carbon ions triggered inflammatory signaling and accelerated differentiation of keratinocytes to a similar extent as X-rays at the same doses. High doses of carbon ions were more effective than X-rays in reducing proliferation and inducing abnormal differentiation. In contrast, changes identified following low-dose exposure (≤0.5 Gy) were induced more effectively after X-ray exposure, i.e., enhanced proliferation and change in the polarity of basal cells.

Differential regulation of the Hippo pathway by adherens junctions and apical–basal cell polarity modules

Adherens junctions (AJs) and cell polarity complexes are key players in the establishment and maintenance of apical-basal cell polarity. Loss of AJs or basolateral polarity components promotes tumor formation and metastasis. Recent studies in vertebrate models show that loss of AJs or loss of the basolateral component Scribble (Scrib) cause deregulation of the Hippo tumor suppressor pathway and hyperactivation of its downstream effectors Yes-associated protein (YAP) and Transcriptional coactivator with PDZ-binding motif (TAZ). However, whether AJs and Scrib act through the same or independent mechanisms to regulate Hippo pathway activity is not known. Here, we dissect how disruption of AJs or loss of basolateral components affect the activity of the Drosophila YAP homolog Yorkie (Yki) during imaginal disc development. Surprisingly, disruption of AJs and loss of basolateral proteins produced very different effects on Yki activity. Yki activity was cell-autonomously decreased but non-cell-autonomously elevated in tissues where the AJ components E-cadherin (E-cad) or α-catenin (α-cat) were knocked down. In contrast, scrib knockdown caused a predominantly cell-autonomous activation of Yki. Moreover, disruption of AJs or basolateral proteins had different effects on cell polarity and tissue size. Simultaneous knockdown of α-cat and scrib induced both cell-autonomous and non-cell-autonomous Yki activity. In mammalian cells, knockdown of E-cad or α-cat caused nuclear accumulation and activation of YAP without overt effects on Scrib localization and vice versa. Therefore, our results indicate the existence of multiple, genetically separable inputs from AJs and cell polarity complexes into Yki/YAP regulation.

AmotL2 disrupts apical-basal cell polarity and promotes tumour invasion.

The establishment and maintenance of apical-basal cell polarity is essential for the functionality of glandular epithelia. Cell polarity is often lost in advanced tumours correlating with acquisition of invasive and malignant properties. Despite extensive knowledge regarding the formation and maintenance of polarity, the mechanisms that deregulate polarity in metastasizing cells remain to be fully characterized. Here we show that AmotL2 expression correlates with loss of tissue architecture in tumours from human breast and colon cancer patients. We further show that hypoxic stress results in activation of c-Fos-dependent expression of AmotL2 leading to loss of polarity. c-Fos/hypoxia-induced p60 AmotL2 interacts with the Crb3 and Par3 polarity complexes retaining them in large vesicles and preventing them from reaching the apical membrane. The resulting loss of polarity potentiates the response to invasive cues in vitro and in vivo in mice. These data provide a molecular mechanism how hypoxic stress deregulates cell polarity during tumour progression.

Inhibition of RHO–ROCK signaling enhances ICM and suppresses TE characteristics through activation of Hippo signaling in the mouse blastocyst

Specification of the trophectoderm (TE) and inner cell mass (ICM) lineages in the mouse blastocyst correlates with cell position, as TE derives from outer cells whereas ICM from inner cells. Differences in position are reflected by cell polarization and Hippo signaling. Only in outer cells, the apical–basal cell polarity is established, and Hippo signaling is inhibited in such a manner that LATS1 and 2 (LATS1/2) kinases are prevented from phosphorylating YAP, a key transcriptional co-activator of the TE-specifying gene Cdx2. However, the molecular mechanisms that regulate these events are not fully understood. Here, we showed that inhibition of RHO–ROCK signaling enhances ICM and suppresses TE characteristics through activation of Hippo signaling and disruption of apical–basal polarity. Embryos treated with ROCK inhibitor Y-27632 exhibited elevated expression of ICM marker NANOG and reduced expression of CDX2 at the blastocyst stage. Y-27632-treated embryos failed to accumulate YAP in the nucleus, although it was rescued by concomitant inhibition of LATS1/2. Segregation between apical and basal polarity regulators, namely PARD6B, PRKCZ, SCRIB, and LLGL1, was dampened by Y-27632 treatment, whereas some of the polarization events at the late 8-cell stage such as compaction and apical localization of p-ERM and tyrosinated tubulin occurred normally. Similar abnormalities of Hippo signaling and apical–basal polarization were also observed in embryos that were treated with RHO GTPases inhibitor. These results suggest that RHO–ROCK signaling plays an essential role in regulating Hippo signaling and cell polarization to enable proper specification of the ICM and TE lineages.

ILK modulates epithelial polarity and matrix formation in hair follicles

Hair follicle morphogenesis requires coordination of multiple signals and communication between its epithelial and mesenchymal constituents. Cell adhesion protein platforms, which include integrins and integrin-linked kinase (ILK), are critical for hair follicle formation. However, their precise contribution to this process is poorly understood. We show that in the absence of ILK, the hair follicle matrix lineage fails to develop, likely due to abnormalities in development of apical-basal cell polarity, as well as in laminin-511 and basement membrane assembly at the tip of the hair bud. These defects also result in impaired specification of hair matrix and absence of precortex and inner sheath root cell lineages. The molecular pathways affected in ILK-deficient follicles are similar to those in the absence of epidermal integrin β1 and include Wnt, but not sonic hedgehog, signaling. ILK-deficient hair buds also show abnormalities in the dermal papilla. Addition of exogenous laminin-511 restores morphological and molecular markers associated with hair matrix formation, indicating that ILK regulates hair bud cell polarity and functions upstream from laminin-511 assembly to regulate the developmental progression of hair follicles beyond the germ stage.

Claudin expression and tight junction protein localization in the lining epithelium of the keratocystic odontogenic tumors, dentigerous cysts, and radicular cysts

The aim of this study was to evaluate the expression and localization of tight junction proteins (TJPs) or claudins in the keratocystic odontogenic tumor (KCOT) and to correlate with its biological behavior. Five claudins (-1, -3, -4, -5, and 7) were examined immunohistochemically in 25 KCOTs and compared with 10 dentigerous cysts (DCs) and 10 radicular cysts (RCs). Marked claudin-3 loss of expression in KCOT basal layer (n=24/25; 96%) compared with DCs (n=1/10; 10%) and RCs (n=5/10; 50%) (P<.05) suggests that claudin-3 downregulation may indicate altered or loss of basal cell polarity and impaired barrier function of KCOT lining epithelium and this might contribute indirectly to its biological behavior. In contrast, claudins-1, -4, -5, and -7 distribution patterns were less distinctive in all three entities, suggesting that these TJP molecules probably play limited roles in influencing their different growth potentials. Present findings suggest that differential claudin expressions in the lining epithelium of KCOTs, DCs, and RCs probably reflect their neoplastic or nonneoplastic nature.

Immunohistochemical localization of multiple aquaporins in eel (Anguilla rostrata) kidney

Although there have been a few studies investigating the location of teleost fish aquaporins. To date little is still known concerning this topic. In the eel, eleven aquaporin genes have been cloned and sequenced from osmoregulatory tissues such as gill, gut and kidney and custom antibodies raised against specific aquaporin peptide antigens. Results show that eel aquaporin 1 (aquaporin 1) is expressed in the apical membranes of a subset of renal tubules and in endothelial cells lining blood vessels as shown previously. A duplicate copy of aquaporin1, AQP1dup (AQP1b using zebrafish nomenclature) was also expressed in a subset of renal tubules but was located in vesicles in the apical pole of the tubule cells rather than in the apical membrane. Aquaporin 8 (AQP8ab in zebrafish) was also expressed in a subset of renal tubules but was located in the basal pole of cells and also stained red blood cells, whereas AQP8b (AQP8aa in zebrafish) expression was located in and adjacent to, cells expressing chromogenic pigment granules. Aquaporin 4b, a novel eel aquaporin was expressed in lines or rings of cells, in unknown structures not associated with either renal tubules or blood vessels. For aquaglyceroporins, AQP3 stained only red blood cells whereas AQPe (AQP10b in zebrafish), stained connective tissue with weak staining in the basal pole of some renal tubules.C.P. Cutler is funded by the National Science Foundation NSF IOS 0844818.

Meredithblackwellia eburnea gen. et sp. nov., Kriegeriaceae fam. nov. and Kriegeriales ord. nov.—toward resolving higher-level classification in Microbotryomycetes

A field survey of ballistosporic yeasts in a Neotropical forest yielded a new species isolated from a fern leaf. The isolate is a cream-colored butyrous yeast that reproduces by budding. Budding occurs at both the apical and basal cell poles; occasionally multiple budding events co-occur, giving rise to rosette-like clusters of cells at both poles of the yeast mother cell. DNA sequences of large and small subunit and the internal transcribed spacer regions of the nuclear ribosomal DNA cistron indicated an affinity to Microbotryomycetes, Pucciniomycotina. A new genus, Meredithblackwellia, is proposed to accommodate the new species, M. eburnea (type strain MCA4105). Based on phylogenetic analyses, Meredithblackwellia is related to Kriegeria eriophori, a sedge parasite, to an aquatic fungus Camptobasidium hydrophilum and to several recently described anamorphic yeasts that have been isolated from plant material or psychrophilic environments. Morphological and ultrastructural studies confirm the relatedness of M. eburnea to these taxa and prompted the re-evaluation of higher-level classification within Microbotryomycetes. We propose here a new order, Kriegeriales, and place two families, Kriegeriaceae fam. nov. and Camptobasidiaceae R.T. Moore, within it. Our study re-emphasizes the need for systematic revision of species described in Rhodotorula.