Evolutionary dynamics of repetitive DNA in semaprochilodus (characiformes, prochilodontidae): a fish model for sex chromosome differentiation.

Distribution of 6 microsatellites and 5 transposable elements on the chromosomes of Semaprochilodus taeniurus and S. insignis, commonly referred to as Jaraqui, was performed using their physical mapping with fluorescence in situ hybridization. In this study, we aim to understand the evolutionary dynamics in genomes of S. taeniurus and S. insignis by comparing the position, abundance and contribution of the repetitive sequences in the origins and differentiation of a ZZ/ZW sex chromosome system in S. taeniurus. Results revealed that distribution patterns of repetitive DNAs along the chromosomes varied considerably. Hybridization signals were observed on several autosomes in both species; however, in S. taeniurus genome, the repetitive sequences were more abundant. In addition, large clusters of known repetitive sequences were detected in sex chromosomes of S. taeniurus. This observation is notable because the accumulation of repetitive DNAs could reflect the degradation of genetic activities and the differentiation of protosex chromosomes, evolving into the heteromorphic ZW pair observed in S. taeniurus.

Cytogenetics of Synbranchiformes: a comparative analysis of two Synbranchus Bloch, 1795 species from the Amazon.

Synbranchidae belongs to the Synbranchiformes and occurs in Africa, Asia, Australia, Mexico, and Central and South America. This family comprises four genera: Synbranchus, Ophisternon, Monopterus, and Macrotrema. Only two are known from the neotropical region, Ophisternon and Synbranchus. According to current classification, Synbranchus has three valid species: S. marmoratus (Bloch 1795), S. madeirae (Rosen and Rumney 1972), and S. lampreia (Favorito, Zanata and Assumpção 2005). Thus the present research is aimed to cytogenetically characterize (by classical and molecular methods) two syntopic species-S. aff. lampreia and S. madeirae-from the central Amazon basin to validate the taxonomy of both species and provide a revisionary discussion on the cytogenetics of Synbranchiformes. Synbranchus aff. lampreia was found to possess 2n = 44 chromosomes (6 m + 2st + 36a, NF = 50), while S. madeirae had 2n = 46 chromosomes (6 m + 2st + 38a, NF = 52). Constitutive heterochromatin was dominant in the centromeric and terminal regions of most of the chromosomes in both species, although the precise distribution patterns were species-specific. The nucleolar organizing region was single in S. aff. lampreia and multiple in S. madeirae, as indicated by both AgNO(3) and hybridization using 18S rDNA probes. The 5S rDNA sites were located interstitially on the long arms of an acrocentric pair in both species, and the telomeric probe did not show any interstitial sites in either species. These data indicate the occurrence of interspecific karyotypic variability in Synbranchus and suggest that taxonomic review for this genus is necessary.

Comparative cytogenetics of spiny rats of the genus Proechimys (Rodentia, Echimyidae) from the Amazon region.

We made a comparative analysis of the cytogenetics of spiny rat species of the genus Proechimys collected from several sites of the Madeira River basin (Amazonas State, Brazil) and Jari River valley (Pará State, Brazil). Individuals were assigned to three groups based on diploid and fundamental numbers: 2n = 28, FN = 46 (P. cuvieri and P. gr. longicaudatus); 2n = 38, FN = 52 (Proechimys gr. guyannensis), and 2n = 40, FN = 54 (P. gardneri). The nucleolar organizer region (NOR) was interstitial on the long arm of one submetacentric pair, as seen in all species of Proechimys analyzed thus far. However, its position in the karyotype was variable. A duplication of the NOR in one of the homologues was detected in P. gr. longicaudatus from the Aripuanã basin along the mid Madeira. The C-band pattern varied between species and, together with the NOR, allowed the identification of two evolutionary units in P. gr. longicaudatus in the region of the mid Madeira River (cytotypes A and B). The morphology and banding of the sex chromosomes were species specific. A range extension is suggested for the geographic distribution of P. gardneri and P. gr. longicaudatus. Moreover, we suggest that species of Proechimys with 2n = 38 chromosomes are restricted to east of the Negro River and north of the Amazon River. We also revised the published chromosome data available for Proechimys.

CompCytogen of two of the smallest Amazonian fishes: Fluviphylax simplex Costa, 1996 and Fluviphylax zonatus Costa, 1996 (Cyprinodontiformes, Poeciliidae).

The genus Fluviphylax Whitley, 1965is comprized of five valid species (Fluviphylax pygmaeus Myers et Carvalho, 1955, Fluviphylax zonatus, Fluviphylax simplex, Fluviphylax obscurus Costa, 1996,and Fluviphylax palikur Costa et Le Bail, 1999), which are endemic to the Amazon region. These fishes are the smallest known South American vertebrates and among the smallest know vertebrates on Earth. All species but the type Fluviphylax pygmaeus have been described in late 1990's, and much remains unknown about the biology, taxonomy and systematics of this group of fishes. The aims of the present study were to establish the diploid and haploid number of Fluviphylax zonatus and Fluviphylax simplex, and to find species-specific markers for the discrimination of taxa. The diploid number for both species was 48 chromosomes, with no sex chromosome heteromorphism. Fluviphylax zonatus exhibited the karyotypic formula 4m+8sm+22st+14a and FN=82, and Fluviphylax simplex exhibited 4m+16sm+18st+10a and FN=86. The determination of the total mean length of the chromosomes and their grouping into five size classes demonstrated different chromosome composition of the two species. This difference was further supported by the distribution of constitutive heterochromatin. The meiotic analysis revealed 24 bivalents in both species, but Fluviphylax zonatus exhibited chromosomes with late pairing of the telomeric portions in the pachytene. These data reveal that cytogenetic characterization is useful and important for the discrimination of these species. Our study further indicates that this method could be employed in the analysis of other species of small fishes that are difficult to distinguish using traditional morphological traits or are morphologically cryptic.

Variability of 18S rDNA locus among Symphysodon fishes: chromosomal rearrangements.

Three species of cichlids belonging to the genus Symphysodon have demonstrated interspecific and intraspecific variation in nucleolus organizer regions (NOR) detected with silver nitrate. In order to understand the evolution of this marker in the genus, the structural variability of these sequences in mitotic chromosomes from Symphysodon aequifasciatus, Symphysodon discus and Symphysodon haraldi was investigated using both silver nitrate impregnation and hybridization of the 18S rRNA gene probe. For the three species, the two markers were intraspecifically and interspecifically variable both in the number and in the size of the sites. This polymorphism may stem from duplications and translocations, which suggests that structural chromosome rearrangements effectively act in the karyoevolution of wild Symphysodon species and may have favoured the adaptability of these fishes to diverse aquatic environments in the Amazon.

Intriguing evidence of translocations in Discus fish (Symphysodon, Cichlidae) and a report of the largest meiotic chromosomal chain observed in vertebrates.

As part of a program to understand the genetics of Amazonian ornamental fish, classical cytogenetics was used to analyze Symphysodon aequifasciatus, S. discus and S. haraldi, popular and expensive aquarium fishes that are endemic to the Amazon basin. Mitotic analyses in Symphysodon have shown some odd patterns compared with other Neotropical cichlids. We have confirmed that Symphysodon species are characterized by chromosomal diversity and meiotic complexity despite the fact that species share the same diploid number 2n=60. An intriguing meiotic chromosomal chain, with up to 20 elements during diplotene/diakinesis, was observed in S. aequifasciatus and S. haraldi, whereas S. discus only contains typical bivalent chromosomes. Such chromosomal chains with a high number of elements have not been observed in any other vertebrates. We showed that the meiotic chromosomal chain was not sex related. This observation is unusual and we propose that the origin of meiotic multiples in males and females is based on a series of translocations that involved heterochromatic regions after hybridization of ancestor wild Discus species.

Comparative cytogenetic analysis of the genus symphysodon (discus fishes, cichlidae): chromosomal characteristics of retrotransposons and minor ribosomal DNA.

As part of a genetic screening program for wild Discus fishes, we analyzed karyotypes and cytogenetic characteristics of Symphysodon aequifasciatus, S. discus and S. haraldi using C-banding and fluorescent in situ hybridization (FISH) with the Rex3 retrotransposon and 5S rDNA probes in mitotic and meiotic chromosomes. In the 3 species, diploid chromosome number was 2n = 60 and karyotypes contained predominantly meta-submetacentric chromosomes. C-banding showed blocks of constitutive heterochromatin mainly in the pericentromeric region. Physical mapping of repetitive 5S rDNA sequences and Rex3 retrotransposons in mitotic and meiotic chromosomes showed partial colocalization of constitutive heterochromatin and repetitive elements. Correlations among the accumulation of repetitive elements, heterochromatinization and chromosome rearrangements have been hypothesized to explain the karyotype differentiation in the Symphysodon genus. The role of repetitive elements in adaptation to highly diverse habitats, as well as in the generation of the phenotypic and genetic variability found in wild Discus populations, needs to be further investigated.

Mechanisms of chromosomal evolution and its possible relation to natural history characteristics in Ancistrus catfishes (Siluriformes: Loricariidae).

Ancistrus is the most speciose genus of the tribe Ancistrini, with 58 valid species and many yet to be described. Cytogenetic studies were conducted on five apparently undescribed species from the Amazon basin, which showed different diploid numbers: Ancistrus sp. Purus (2n = 34); Ancistrus sp. Macoari (2n = 46); Ancistrus sp. Dimona (2n = 52); Ancistrus sp. Vermelho (2n = 42) and Ancistrus sp. Trombetas (2n = 38). All species possessed only one pair of NOR-carrying chromosomes, but with extensive variation in both the location on the chromosome as well as in the position of the ribosomal sites on the karyotype. The karyotypic evolution of Ancistrus species seems to be based on chromosomal rearrangements, with a tendency to a reduction of the diploid number. Two new instances of XX/XY sex chromosomes for Ancistrus species, based on the heteromorphism in the male karyotype, were also recorded. The large karyotypic diversity among Ancistrus species may be related to biological and behavioural characteristics of these fish that include microhabitat preferences, territoriality and specialized reproductive tactics. These characteristics may lead to a fast rate of fixation of chromosomal mutations and eventually speciation across the basin.

Parotid gland involvement, the presenting sign of high grade non-Hodgkin lymphoma in two patients with Gaucher disease and sicca syndrome.

Increased risk of haematological malignancies has been described in Gaucher disease patients; however, high-grade lymphoma has been rarely observed. We report two patients with Gaucher disease and sicca syndrome diagnosed with aggressive lymphoma involving the parotid gland. A 29-year-old woman with Gaucher disease developed tumour of the left parotid gland. She reported chronic arthralgias, xerostomia and xerophthalmia. Parotid gland biopsy disclosed diffuse large B-cell lymphoma. No lymphadenopathy was found. Bone biopsy revealed focal lymphomatous infiltration consistent with stage IV disease. MACOP-B chemotherapy regimen (cyclophosphamide, adriamycin, methotrexate, bleomycin, vincristine, prednisone) resulted in complete remission for 15 years. A 76-year-old patient with Gaucher disease suffered from dry-mouth feeling. He developed a left parotid gland tumour. CT scan disclosed diffuse lymphadenopathy, pleural effusion and multiple lung nodules. A cervical lymph node biopsy revealed mantle cell lymphoma. Fine-needle aspiration of the parotid gland showed lymphoma cells. Immunochemotherapy with fludarabine, cyclophosphamide and rituximab resulted in complete remission. Accumulation of the glucocerebroside in Gaucher disease activates macrophages, inducing release of pro-inflammatory cytokines which may be involved in the pathogenesis of second malignancy. Patients with Gaucher disease bear an increased risk of haematological malignancies; however, aggressive lymphoma has been described only occasionally. In both our patients the presenting sign of lymphoma was tumour of the parotid gland. The patients suffered from sicca syndrome, which increases risk for developing lymphoma. The underlying Gaucher disease and sicca syndrome might be implicated as immunological triggers for lymphoma occurrence and its propensity for the parotid gland in these patients.

Non-Hodgkin's lymphoma presenting as advanced ovarian cancer--a case report and review of literature.

Non-Hodgkin's lymphoma involving the ovaries is unusual and may cause confusion for the clinician since its presentation might resemble other, much more frequent tumors. Malignant lymphoid cells may occur in the ovary either as a primary neoplasm or as a secondary manifestation of a disseminated occult or known disease. The most common presenting signs or symptoms of malignant lymphomas involving the ovaries are abdominal or pelvic pain or mass. We present here a unique case of non-Hodgkin's lymphoma involving the ovaries presenting as advanced ovarian cancer with a pelvic mass, pleural effusion, and marked elevation of CA-125.

B chromosomes in Amazonian cichlid species.

B chromosomes are reported in three different Amazonian cichlid species. One to three supernumerary microchromosomes were detected in the peacock bass Cichla monoculus (4 out of 28 specimens) and Cichla sp. (4 out of 13 specimens), and pike cichlids Crenicichla reticulata (2 out of 5 specimens), with no similar standard chromosomal morphology. C-banding revealed that B chromosomes are totally heterochromatic. We suggest two scenarios for the origin of these B chromosomes either by chromosomal breakdowns due to mutagenic action of methyl mercury present in the aquatic environment or by interspecific origin due to hybridization events.

Necrosis of the epididymis in a premature infant with patent ductus arteriosus and diastolic aortic steal: ischemia or torsion?

UNLABELLED: We describe a case of isolated ischemic necrosis of the epididymis in a premature newborn with aortic steal syndrome, secondary to a large patent ductus arteriosus (PDA). Neither this finding nor the possible underlying pathogenesis has been previously described. CONCLUSION: In this report our knowledge of the potential complications of PDA in the premature neonate is extended.

Karyological, biochemical, and physiological aspects of Callophysus macropterus (Siluriformes, Pimelodidae) from the Solimöes and Negro Rivers (Central Amazon)

Karyological characteristics, i.e., diploid number, chromosome morphology and nucleolus organizer regions (NORs), biochemical characteristics, i.e., electrophoretic analysis of blood hemoglobin and the tissue enzymes lactate dehydrogenase (LDH), malate dehydrogenase (MDH), alcohol dehydrogenase (ADH), and phosphoglucose isomerase (PGI), and physiological characteristics, i.e., relative concentration of hemoglobin and intraerythrocytic concentrations of organic phosphates were analyzed for the species Callophysus macropterus collected from Marchantaria Island (white water system - Solimöes River) and Anavilhanas Archipelago (black water system - Negro River). Karyological and biochemical data did not reveal significant differences between specimens collected at the two sites. However, the relative distribution of hemoglobin bands I and III (I = 16.33 ñ 1.05 and III = 37.20 ñ 1.32 for Marchantaria specimens and I = 6.33 ñ 1.32 and III = 48.05 ñ 1.55 for Anavilhanas specimens) and levels of intraerythrocytic GTP (1.32 ñ 0.16 and 2.76 ñ 0.18 for Marchantaria and Anavilhanas specimens, respectively), but not ATP or total phosphate, were significantly different, indicating a physiological adaptation to the environmental conditions of these habitats. It is suggested that C. macropterus specimens from the two collecting sites belong to a single population, and that they adjusted some physiological characteristics to adapt to local environmental conditions.

Karyological, biochemical, and physiological aspects of Callophysus macropterus (Siluriformes, Pimelodidae) from the Solimões and Negro Rivers (central Amazon).

Karyological characteristics, i.e., diploid number, chromosome morphology and nucleolus organizer regions (NORs), biochemical characteristics, i.e., electrophoretic analysis of blood hemoglobin and the tissue enzymes lactate dehydrogenase (LDH), malate dehydrogenase (MDH), alcohol dehydrogenase (ADH), and phosphoglucose isomerase (PGI), and physiological characteristics, i.e., relative concentration of hemoglobin and intraerythrocytic concentrations of organic phosphates were analyzed for the species Callophysus macropterus collected from Marchantaria Island (white water system--Solimões River) and Anavilhanas Archipelago (black water system--Negro River). Karyological and biochemical data did not reveal significant differences between specimens collected at the two sites. However, the relative distribution of hemoglobin bands I and III (I = 16.33 +/- 1.05 and III = 37.20 +/- 1.32 for Marchantaria specimens and I = 6.33 +/- 1.32 and III = 48.05 +/- 1.55 for Anavilhanas specimens) and levels of intraerythrocytic GTP (1.32 +/- 0.16 and 2.76 +/- 0.18 for Marchantaria and Anavilhanas specimens, respectively), but not ATP or total phosphate, were significantly different, indicating a physiological adaptation to the environmental conditions of these habitats. It is suggested that C. macropterus specimens from the two collecting sites belong to a single population, and that they adjusted some physiological characteristics to adapt to local environmental conditions.

Expression of the adherens junction protein vinculin in human basal and squamous cell tumors: relationship to invasiveness and metastatic potential.

The acquisition of an invasive or metastatic phenotype in malignant neoplasms is often correlated with reduced cellular adhesiveness. We investigated the expression of the adhesion-associated cytoplasmic protein, vinculin, in normal and neoplastic human squamous epithelia, as well as in metastases of squamous cell carcinomas, and correlated the results with invasiveness and metastatic potential. Tissue samples from various tumors were examined, including basal cell carcinomas (BCC), keratoacanthomas, and squamous cell carcinomas (SCC). In addition, lymph node metastases from nine of the SCC were tested in this study. Our results indicate that most BCC, keratoacanthomas, and in situ SCC display strong positive staining for vinculin. The level of immunolabeling for vinculin and its pattern of distribution in the low malignant, nonmetastasizing lesions was similar to those observed in normal squamous epithelia. In contrast, in SCC, which are invasive and possess metastatic potential, as well as in their metastases, vinculin labeling was negative or poor, irrespective of their degree of differentiation. In conclusion, poor vinculin labeling in tumors of squamous epithelial origin examined here appears to be related to the metastatic potential of the tumor. Vinculin immunostaining of primary tumors originating in stratified squamous epithelia may thus be of value in helping to determine the metastatic potential of these neoplasms.

Adrenal cortical adenoma with extensive fat cell metaplasia.

This report describes a large adrenal cortical tumor with a significant component of mature adipose tissue in a 40 year old woman. No bone marrow elements were identified in multiple sections. This lesion, representing most likely an adrenal cortical adenoma with extensive fat cell metaplasia, has not been previously reported and must be differentiated from adrenal myelolipoma.