Membrane extensions are associated with proper anterior migration of muscle cells during Caenorhabditis elegans embryogenesis

C. elegans body wall muscle is formed after a series of well-orchestrated steps. With the onset of specification embryonic muscle cells accumulate under the hypodermal seam cells at the left and right sides of the embryo. Shortly thereafter they begin to migrate dorsally and ventrally resting beneath the dorsal and ventral hypodermis eventually forming the four muscle quadrants present upon hatching. In this study we describe the plasma membrane dynamics of these migrating cells and observe the extension of filopodia and lamellipodia during dorso-ventral migration but not during the earlier stages of accumulation. We also describe an anterior migration event during embryonic muscle morphogenesis, whereby the anterior-most pair of cells in each of the four muscle quadrants extends long processes to the anterior tip of the developing embryo. Anteriormost muscle cells then follow these extensions into their final positions in the developing embryo. Using RNAi and mutant analysis, we have identified laminin as being involved in mediating the dorsal-ventral muscle migrations. Finally we show that the α-integrin INA-1, the ephrin VAB-2 and its receptor VAB-1 and the Robo receptor SAX-3 indirectly promote the proper extension of the ventral anterior muscle processes by organizing the embryonic neurons so as to provide a clear path for muscle membrane extension.     

Brain mast cells are influenced by chemosensory cues associated with estrus induction in female prairie voles (Microtus ochrogaster)

Historically, the brain has been viewed as protected from the infiltration of peripheral hematopoietic cells by the blood-brain barrier. However, numerous immune cell types have been found in the central nervous system (CNS). Mast cells, granulocytic immune cells, are found in the CNS of birds and mammals and their numbers and location are influenced by both extrinsic and intrinsic factors, including reproductive behavior and endocrine status. The present study used female prairie voles (Microtus ochrogaster) to investigate the interactions between brain mast cells and stimuli associated with estrus induction. Unlike spontaneous ovulators such as rats and mice, female prairie voles are induced into estrus by chemosensory stimuli present in conspecific male urine. Prior to estrus induction, female voles have undetectable concentrations of estrogen that rise rapidly following exposure to a male or male urine. In the first experiment, we examined whether mast cells may be influenced by estrus induction. Female voles exposed to conspecific male urine had increased numbers of mast cells in the main olfactory bulbs and epithalamus (medial habenula), but not the thalamus or median eminence, relative to control groups. Next, to determine if this mast cell increase was the result of elevated estrogen concentrations, female voles were injected with estradiol or vehicle and brain mast cell numbers analyzed. No differences in brain mast cell numbers were observed between estradiol-injected and control females in any brain area investigated. Together, these results lend further support to the contention that mast cell numbers and/or distribution can be influenced by reproductively relevant stimuli and underscore the utility of this vole model for delineating the function of brain mast cells.     

Ornithodiplostomum ptychocheilus: migration to the brain of the fish intermediate host, Pimephales promelas.

Migration of cercariae of the diplostomatid trematode, Ornithodiplostomum ptychocheilus, to the brain of the fathead minnow, Pimephales promelas, takes place via directed, nonrandom movement. Penetration of the fish epidermis is rapid and is essentially complete by 2 hr postinfection. Migration to the central nervous system occurs almost exclusively via the general body musculature and connective tissue, although a few cercariae gain direct access to the nervous system via the eyes. Cercariae enter either the neural canal and spinal cord, or the brain via the spinal or cranial nerves and their associated foramina, although cercariae appear to remain in (on) these peripheral nerves for only a short time. Cercariae associated with cranial nerves continue to the brain. Those becoming associated with spinal nerves travel up the neural canal and (or) spinal cord to the brain. Data suggest that most arrive at the brain via the neural canal and spinal cord. Within the brain, most developing metacercariae (neascus-type) occur in the optic lobes and cerebellum. Whether this is “selective localization” or merely the result of the larger space afforded by these brain regions could not be determined.     

DLC-1, a GTPase-activating protein for Rho, is associated with cell proliferation, morphology, and migration in human hepatocellular carcinoma

Geranylgeranylacetone (GGA), an isoprenoid compound, is an anti-ulcer drug developed in Japan. In our previous study, GGA was shown to inhibit ovarian cancer invasion by attenuating Rho activation [K. Hashimoto, K. Morishige, K. Sawada, M. Tahara, S. Shimizu, M. Sakata, K. Tasaka, Y. Murata, Geranylgeranylacetone inhibits lysophosphatidic acid-induced invasion of human ovarian carcinoma cells in vitro. Cancer 103 (2005) 1529-1536.]. In the present study, GGA treatment inhibited ovarian cancer progression in vitro and suppressed the tumor growth and ascites in the in vivo ovarian cancer model. In vitro analysis, treatment of cancer cells by GGA resulted in the inhibition of cancer cell proliferation, the inactivation of Ras, and the suppression of tyrosine phosphorylation of mitogen-activated protein kinase (MAPK). In conclusion, this is the first report that GGA inhibited ovarian cancer progression and the anti-tumor effect by GGA is, at least in part, derived not only from the suppression of Rho activation but also Ras-MAPK activation.     

Cytoplasmic male sterility and fertility restoration in wheat are not associated with rearrangements of mitochondrial DNA in the gene regions for cob,coxII, or coxI

In comparing the genetic organization and exploring the molecular basis of cytoplasmic male sterility (CMS) in wheat, mitochondrial DNAs (mtDNA) from Triticum aestivum, T. timopheevi, CMS alloplasmic wheat with T. aestivum nucleus and T. timopheevi mitochondria, and fertility-restored lines were compared by hybridization analysis with specific probes for three gene regions: CoxII, cob, and coxI. Minor differences between T. aestivum- and T. timopheevi-derived sources were found for gene regions for coxII and cob. For coxI, there are significant differences between T. timopheevi-derived mtDNAs and T. aestivum mtDNA extending beyond an 8 kb distance. All T. timopheevi-derived mtDNA sources have a chimeric gene region (orf256) with part of the upstream coxI gene region, including some coxI-coding region, preceding coxI. The part of orf256 that does not include any of coxI and the 3-flanking region of CMS coxI are not found in T. aestivum mtDNA. Neither orf256 nor the CMS 3-flanking region of coxI are found in T. timopheevi or T. aestivum chloroplastic or nuclear DNA. There do not appear to be DNA sequence differences for the three gene regions studied that are related to either CMS or fertility-restored states.