Evolution of MicroRNA Biogenesis Genes in the Sterlet (Acipenser ruthenus) and Other Polyploid Vertebrates

MicroRNAs play a crucial role in eukaryotic gene regulation. For a long time, only little was known about microRNA-based gene regulatory mechanisms in polyploid animal genomes due to difficulties of polyploid genome assembly. However, in recent years, several polyploid genomes of fish, amphibian, and even invertebrate species have been sequenced and assembled. Here we investigated several key microRNA-associated genes in the recently sequenced sterlet (Acipenser ruthenus) genome, whose lineage has undergone a whole genome duplication around 180 MYA. We show that two paralogs of drosha, dgcr8, xpo1, and xpo5 as well as most ago genes have been retained after the acipenserid-specific whole genome duplication, while ago1 and ago3 genes have lost one paralog. While most diploid vertebrates possess only a single copy of dicer1, we strikingly found four paralogs of this gene in the sterlet genome, derived from a tandem segmental duplication that occurred prior to the last whole genome duplication. ago1,3,4 and exportins1,5 look to be prone to additional segment duplications producing up to four-five paralog copies in ray-finned fishes. We demonstrate for the first time exon microsatellite amplification in the acipenserid drosha2 gene, resulting in a highly variable protein product, which may indicate sub- or neofunctionalization. Paralogous copies of most microRNA metabolism genes exhibit different expression profiles in various tissues and remain functional despite the rediploidization process. Subfunctionalization of microRNA processing gene paralogs may be beneficial for different pathways of microRNA metabolism. Genetic variability of microRNA processing genes may represent a substrate for natural selection, and, by increasing genetic plasticity, could facilitate adaptations to changing environments.

Cytogenetic, Molecular, and Phenotypic Characterization of a Patient with de novo Derivative Chromosome 18 and Review of the Literature

We present a patient with a de novo derivative chromosome 18 which includes a terminal deletion of 18p and a terminal duplication of 18q accompanied by a cryptic duplication of 18p. The girl had mild dysmorphic features such as micro-retrognathia, upslanted palpebral fissures, bilateral epicanthus, high palate, low-set ears, short neck, and full cheeks. She also had an H-type tracheoesophageal fistula which required surgery. Her cognitive and motor skills were delayed. Karyotype analysis showed an additional segment on the short arm of chromosome 18. Chromosomal microarray revealed a 7.3-Mb terminal loss from 18p11.32 to 18p11.23, a 22.2-Mb terminal gain from 18q21.31 to 18q23, and a 3.9-Mb interstitial gain from 18p11.22 to 18p11.21. We hypothesize that the mother has gonadal mosaicism for normal chromosome 18, der(18)dup(p11.22p11.21), and der(18)dup(p11. 22p11.21)inv(18)(p11.22q21.31), or both the terminal del/dup and the interstitial duplication occurred simultaneously.

MODERN ASPECTS OF MULTIFOCAL INTRAOCULAR CORRECTION: A REVIEW

During the last decade multifocal intraocular lenses (IOL) became widely used in cataract surgery and proved to be effective in recovery of visual functions. Lots of clinical studies with different multifocal IOL models showed high effectiveness of multifocal correction to achieve good visual quality for far, intermediate, and near distances. Uncorrected visual acuity at a distance is equal to multifocal and monofocal correction, while uncorrected near vision is significantly better with multifocal IOLs. Additional segment position in asymmetric multifocal IOL models did not significantly influence on visual acuity. Multiple multifocal IOL designs (bifocal, trifocal) and ADD power level provide different functional results for near and intermediate distances which allows to select the specific IOL model depending on the patient`s needs. The review covers the following aspects of multifocal intraocular correction: update for classification of multifocal IOLs, visual acuity (functional results) at different distances after multifocal IOL implantation, comparison of clinical results with different multifocal IOL designs and add power levels, influence of add segment position in asymmetric multifocal IOLs on visual quality, comparison between multifocal and monofocal correction.

Mobilization of qnrB2 and ISCR1 in Plasmids

ABSTRACT The DNA sequences of two IncHI2 plasmids, pEC-IMP and pEC-IMPQ, from metallo-β-lactamase-producing Enterobacter cloacae clinical isolates were determined. The two conjugative plasmids are almost identical, but pEC-IMPQ carries an additional segment containing an orf513 (ISCR1), a truncated 3′ conserved sequence, and a qnrB2. Comparative analyses provide support for the proposed ISCR1-mediated gene mobilization.

The 2-Hydroxycarboxylate Transporter Family: Physiology, Structure, and Mechanism

SUMMARY The 2-hydroxycarboxylate transporter family is a family of secondary transporters found exclusively in the bacterial kingdom. They function in the metabolism of the di- and tricarboxylates malate and citrate, mostly in fermentative pathways involving decarboxylation of malate or oxaloacetate. These pathways are found in the class Bacillales of the low-CG gram-positive bacteria and in the gamma subdivision of the Proteobacteria. The pathways have evolved into a remarkable diversity in terms of the combinations of enzymes and transporters that built the pathways and of energy conservation mechanisms. The transporter family includes H+ and Na+ symporters and precursor/product exchangers. The proteins consist of a bundle of 11 transmembrane helices formed from two homologous domains containing five transmembrane segments each, plus one additional segment at the N terminus. The two domains have opposite orientations in the membrane and contain a pore-loop or reentrant loop structure between the fourth and fifth transmembrane segments. The two pore-loops enter the membrane from opposite sides and are believed to be part of the translocation site. The binding site is located asymmetrically in the membrane, close to the interface of membrane and cytoplasm. The binding site in the translocation pore is believed to be alternatively exposed to the internal and external media. The proposed structure of the 2HCT transporters is different from any known structure of a membrane protein and represents a new structural class of secondary transporters.

Segment Disclosures under SFAS No. 131: Has Business Segment Reporting Improved?

In response to user concerns regarding segment reporting, the FASB issued SFAS No. 131, Reporting Disaggregated Information about a Business Enterprise, in 1997. SFAS No. 131 became effective for fiscal years beginning on or after January 1, 1998. This research examines the segment disclosures of U.S. Global 1000 companies for both 1997 and 1998 to ascertain the impact and effectiveness of SFAS No. 131 in practice. Specifically, this research considers whether the new requirements have resulted in (1) a greater number of line-of-business (LOB) segments for some enterprises, particularly those who claimed to operate in one LOB under SFAS No. 14, (2) enterprises reporting more items of information about each segment, and (3) improved consistency of segment information with other parts of the annual report. The research also addresses whether restructuring by some firms might limit the provision of additional segment information under SFAS No. 131. The findings indicate significant changes from reporting under SFAS No. 14 including increased consistency with information in the MD&A and other annual report disclosures. However, the practices of a significant minority of companies continue to give some cause for concern.

CalpA, a Drosophila calpain homolog specifically expressed in a small set of nerve, midgut, and blood cells.

Calpains are calcium-dependent proteases believed to participate in calcium-regulated signal pathways in cells. Ubiquitous calpains as well as tissue-specific calpains have been found in vertebrates. We isolated cDNA clones for a highly tissue-specific calpain gene from Drosophila melanogaster, CalpA, at 56C-D on the second chromosome. The expression of the CalpA gene product was monitored by using a specific antiserum directed against the product expressed by one cDNA clone. The encoded protein is found in a few neurons in the central nervous system, in scattered endocrine cells in the midgut, and in blood cells. In the blood cell line mbn-2, calpain is associated with a granular component in the cytoplasm. The expression of this protein is more restricted than that of the corresponding transcripts, which are widely distributed in the central nervous system, digestive tract, and other tissues. The sequence of CalpA is closely related to that of vertebrate calpains, but an additional segment is inserted in the calmodulin-like carboxy-terminal domain. This insert contains a hydrophobic region that may be involved in membrane attachment of the enzyme. Differential splicing also gives rise to a minor transcript that lacks the calmodulin-like domain.

Characterization of the gene encoding the glutamic-acid-specific protease of Streptomyces griseus

The complete gene sequence (sprE) for the glutamic-acid-specific serine protease (SGPE) of the gram-positive bacterium Streptomyces griseus is reported. The sprE gene encodes a 355 amino acid pre–pro–mature enzyme. The presence of a glutamic acid residue at the junction of the pro and mature segments of the protein suggests that the enzyme is self-processing. SGPE was found to have extensive homology with the S. griseus proteases A and B. However, there is an additional segment to the pro region of SGPE, lacking in proteases A and B, which has significant homology to the pro region of the α-lytic protease of the gram-negative bacterium Lysobacter enzymogenes. Expression of recombinant SGPE in Bacillus subtilis is also reported, and the enzyme is shown to be self-processing.Key words: serine protease, maturation, expression, propeptide.