The lagena (the third otolith endorgan in vertebrates)

In this review, the structure and functions of the lagena (the third otolith organ) in an evolutionary lineage of the vertebrates are described and discussed. The lagenar macula appears first in the posterior part of the sacculus of elasmobranchs; in these animals, the lagena is considered to be involved in the balance support (orientation with respect to the gravitation force). The lagena as a separate endorgan has been described in teleost fishes; in some species, the lagena is connected with the sacculus, while in other species the interrelations of these structures can be dissimilar. The lagena supplements the functions of the sacculus; in fishes (animals with no special organ of hearing), it is involved in discrimination of sound oscillations, identification of the gravitation vector, and orientation in the course of movements within the vertical plane. In amphibians, the lagena is localized in the posterior part of the sacculus, near the auditory structures; it performs mostly vestibular and (to a much lesser extent) auditory functions. In amniotes, the lagena was first separated from the sacculus; it is localized in the cochlear canal, distally with respect to the hearing organ. Information on the functions of the lagena in amniotes is rather limited and contradictory. Central projections of this organ have been examined practically only in birds. Lagenar afferents project to the vestibular nuclei and cerebellum, while some fibers come to the auditory nuclei of the medulla. The lagena in birds can be related to their navigation abilities (birds are supposed to be capable of orienting within the magnetic field of the Earth due to the magnetic properties of the lagenar otoconia; this structure can also provide detection of movements along the vertical axis. The close proximity between the otolithic and auditory endorgans in the cochlear canal of amniotes can be indicative of the functional significance of these interrelations. This aspect, however, remains at present undiscovered. In mammals (except Monotremata), there is no lagena as an independent endorgan. Neirofiziologiya/Neurophysiology, Vol. 40, No. 2, pp. 160–178, March–April, 2008.     

Evidences for genetic differentiation within the highly endemic and endangered annual fish Austrolebias nigrofasciatus (Cyprinodontiformes: Rivulidae)

Samples of Austrolebias nigrofasciatus (n = 103), an endangered species of annual fish endemic to a small area of the Patos-Mirim lagoon system encompassing the São Gonçalo Channel lowlands, were collected from eight isolated temporary ponds, four located at the known distribution range of the species and four located along the Piratini River lowlands, where morphologically different individuals were found. In the laboratory, fragments of the mitochondrial cytochrome c oxidase I (coI), cytochrome b (cytb) and nuclear rhodopsin (rho) genes were amplified, purified and sequenced for 100, 99 and 58 of these individuals, respectively. Samples were further analysed using phylogenetic and phylogeographic methods to evaluate the patterns of genetic diversity and differentiation presented within and between populations, while assessing their evolutionary history, in order to guide the application of further conservation strategies. We found that the four new populations from the Piratini River lowlands encompass a different lineage of A. nigrofasciatus that diverged from that encountered in the São Gonçalo Channel at approximately 0.165 M years before present, during a population expansion and did not yet attain reciprocal monophyly. This divergence was associated with a glacial event that was preceded by an interglacial period putatively associated with the dispersal. Moreover, significant levels of genetic differentiation and a high number of exclusive haplotypes could be encountered even in micro-geographical scales, as in the comparisons between populations located within the same major lineage, indicating each of them may encompass independent management units. Conservation actions are certainly urgent, especially in the face of signs of a recent bottleneck.     

Cryopreservation of spermatozoa of a transgenic mouse]

Spermatozoa of a homozygous transgenic mouse, in which the firefly luciferase gene was expressed under the control of beta-actin promoter, were frozen at -196 degrees C. One fourth of the frozen sperm was later thawed and used for in vitro fertilization. Thirty-six of 65 oocytes (55.4%) developed to the 2-cell stage. All the 2-cell embryos were transferred to the oviducts of pseudopregnant recipients and 23 young (63.9%, 23/36) were born. All of young analyzed carried the transgene and showed the luciferase gene expression.     

Cell adhesion molecule in the hexactinellid Aphrocallistes vastus

Abstract. The Hexactinellida sponge Aphrocallistes vastus contains a soluble aggregation factor (AF) whose purification has been described in this communication. It is characterized by a S°_20.w value of 37 and a buoyant density of 1.45 g/cm³. The AF is a glycoporteinaceous particle composed of three major protein species; no core structure could be visualized. In the presence of Ca²⁺, the AF causes secondary aggregation of single cells. The aggregation process is temperature, pH, and ionic strength independent within a broad range. Evidence is presented indicating that two (or more) AF molecules are required for the establishment of a stable cell: cell interaction. In contrast to the AFs from demosponges, the hexactinellid AF functions species-unspecifically.     

Effect of Cimetidine and other antihistaminics on the elimination of aminopyrine,phenacetin and caffein

Cimetidine is widely prescribed for the treatment of peptic ulcer disease and has recently been shown to inhibit the metabolism of warfarin, antipyrine and diazepam. To further examine this phenomenon we investigated the effect of various doses of cimetidine and other related drugs on ¹⁴C-aminopyrine, ¹⁴C-phenacetin and ¹⁴C-caffeine breath tests. Cimetidine caused a dose-related inhibition of the metabolism of aminopyrine and caffeine but had no effect on the phenacetin breath test. Metiamide, H₁-antihistamines, phenothiazines and local anesthetics also inhibited the aminopyrine breath test. Cyproheptadine had no effect on either phenacetin or caffeine elimination. This study demonstrates a complex drug-drug interaction which may have widespread clinical implications.     

Getting to the heart of the matter: CCN2 plays a role in cardiomyocyte hypertrophy

Connective tissue growth factor (CTGF/CCN2) is overexpressed in diabetes. Diabetic rats possess myocardial and cardiomyocyte hypertrophy. In a recent report, Wang and colleagues (Am J Physiol Cell Physiol. 2009 Jul 22. [Epub ahead of print]) show that CCN2 directly mediates cardiomyocyte hypertrophy as well as that induced by high glucose and fatty acid. CCN2 acted via the TrkA receptor. These data are the subject of this commentary, and emphasize that CCN2 may be an excellent target for therapy in diabetes.     

Population structure,dispersal and colonization history of the garden bumblebee <Emphasis Type="Italic">Bombus hortorum</Emphasis> in the Western Isles of Scotland

New methods of analysing genetic data provide powerful tools for quantifying dispersal patterns and reconstructing population histories. Here we examine the population structure of the bumblebee Bombus hortorum in a model island system, the Western Isles of Scotland, using microsatellite markers. Following declines in other species, B. hortorum is the only remaining long-tongued bumblebee species found in much of Europe, and thus it is of particular ecological importance. Our data suggest that populations of B. hortorum in western Scotland exist as distinct genetic clusters occupying groups of nearby islands. Population structuring was higher than for other bumblebee species which have previously been studied in this same island group (F_st = 0.16). Populations showed significant isolation by distance. This relationship was greatly improved by using circuit theory to allow dispersal rates to differ over different landscape features; as we would predict, sea appears to provide far higher resistance to dispersal than land. Incorporating bathymetry data improved the fit of the model further; populations separated by shallow seas are more genetically similar than those separated by deeper seas. We argue that this probably reflects events following the last ice age when the islands were first colonized by this bee species (8,500–5,000 ybp), when the sea levels were lower and islands separated by shallow channels would have been joined. In the absence of significant gene flow these genetic clusters appear to have since diverged over the following 5,000 years and arguably may now represent locally adapted races, some occurring on single islands.