Evidence for an adrenergic mechanism in the control of body asymmetry

The effect of phenylephrine, an alpha-1 adrenergic agonist, on development of body asymmetry was studied using a rat whole embryo culture system. Embryos were explanted at the presomite stage, cultured in 100% rat serum containing various concentrations of phenylephrine, and examined at the 20-25 somite stage for sidedness of asymmetric body structures, namely, bulboventricular loop, allantoic placenta, and tail. Phenylephrine treatment resulted in a dose-dependent increase of situs inversus with a maximum incidence of 52%. Coadministration of prazosin, an alpha-1 adrenergic antagonist, almost completely prevented this effect. Our results suggest that receptor-mediated stimulation of the alpha-1 adrenergic pathway is involved in the control of normal body asymmetry in developing rat embryos.     

Activation of α-1 adrenergic receptors modulates the control of left/right sidedness in rat embryos

Presomite stage rat embryos were cultured for 45–49 hr with medium containing various adrenergic agonists and antagonists. -Norepinephrine but not -norepinephrine (several orders of magnitude less potent than the -isomer at α-1 adrenergic receptors) resulted in a dose-dependent increase of situs inversus similar to that found for phenylephrine, an α-1 adrenergic agonist. Prazosin, an α-1 adrenergic antagonist, inhibited phenylephrine-induced situs inversus in a dose-dependent manner. Neither dexmedetomidine, an α-2 adrenergic agonist, nor isoproterenol, a β adrenergic agonist, caused situs inversus. These results provide pharmacological evidence that stimulation of α-1 but not of α-2 and β adrenergic receptors modulates the control of left/right sidedness in rat embryos.     

Molecular epidemiology of adenovirus type 8 (Ad 8) in Taiwan: four subtypes recovered during the period of 1980-1981 from patients with epidemic keratoconjunctivitis

Adenovirus type 8 (Ad 8) has been the major and important causative agent of epidemic keratoconjunctivitis (EKC). By enzymatic cleavage analysis with five endonucleases, PstI, HindIII, BamHI, SalI and SstI, 27 out of 149 Ad 8 isolates recovered from patients with EKC during the period from July, 1980 to July, 1981 in Kaohsiung, Taiwan, were studied. By cleavage patterns, 27 Ad 8 isolates in Kaohsiung were classified into four subtypes which were found to be different from the subtypes (Ad 8A, Ad 8B) prevalent in Sapporo (1).     

Presentation of Various Tactile Sensations Using Micro-Needle Electrotactile Display

Tactile displays provoke tactile sensations by artificially stimulating tactile receptors. While many types of tactile displays have been developed, electrotactile displays that exploit electric stimulation can be designed to be thin, light, flexible and thus, wearable. However, the high voltages required to stimulate tactile receptors and limited varieties of possible sensations pose problems. In our previous work, we developed an electrotactile display using a micro-needle electrode array that can drastically reduce the required voltage by penetrating through the high-impedance stratum corneum painlessly, but displaying various tactile sensations was still a challenge. In this work, we demonstrate presentation of tactile sensation of different roughness to the subjects, which is enabled by the arrangement of the electrodes; the needle electrodes are on the fingertip and the ground electrode is on the fingernail. With this arrangement, the display can stimulate the tactile receptors that are located not only in the shallow regions of the finger but also those in the deep regions. It was experimentally revealed that the required voltage was further reduced compared to previous devices and that the roughness presented by the display was controlled by the pulse frequency and the switching time, or the stimulation flow rate. The proposed electrotactile display is readily applicable as a new wearable haptic device for advanced information communication technology.     

Bone Inner Structure Suggests Increasing Aquatic Adaptations in Desmostylia (Mammalia,Afrotheria)

Background

The paleoecology of desmostylians has been discussed controversially with a general consensus that desmostylians were aquatic or semi-aquatic to some extent. Bone microanatomy can be used as a powerful tool to infer habitat preference of extinct animals. However, bone microanatomical studies of desmostylians are extremely scarce.

Methodology/Principal Findings

We analyzed the histology and microanatomy of several desmostylians using thin-sections and CT scans of ribs, humeri, femora and vertebrae. Comparisons with extant mammals allowed us to better understand the mode of life and evolutionary history of these taxa. Desmostylian ribs and long bones generally lack a medullary cavity. This trait has been interpreted as an aquatic adaptation among amniotes. Behemotops and Paleoparadoxia show osteosclerosis (i.e. increase in bone compactness), and Ashoroa pachyosteosclerosis (i.e. combined increase in bone volume and compactness). Conversely, Desmostylus differs from these desmostylians in displaying an osteoporotic-like pattern.

Conclusions/Significance

In living taxa, bone mass increase provides hydrostatic buoyancy and body trim control suitable for poorly efficient swimmers, while wholly spongy bones are associated with hydrodynamic buoyancy control in active swimmers. Our study suggests that all desmostylians had achieved an essentially, if not exclusively, aquatic lifestyle. Behemotops, Paleoparadoxia and Ashoroa are interpreted as shallow water swimmers, either hovering slowly at a preferred depth, or walking on the bottom, and Desmostylus as a more active swimmer with a peculiar habitat and feeding strategy within Desmostylia. Therefore, desmostylians are, with cetaceans, the second mammal group showing a shift from bone mass increase to a spongy inner organization of bones in their evolutionary history.     

Zebrafish Polycomb group gene ph2alpha is required for epiboly and tailbud formation acting downstream of FGF signaling

We analyzed Polycomb group gene ph2alpha functionally in zebrafish embryos by a gene knock-down procedure using morpholino antisense oligos. Inhibition of ph2alpha message translation resulted in abnormal epibolic movements as well as a thick tailbud or incomplete covering of the yolk plug. At the 24hpf stage, morphants had short trunks and tails, phenotypes similar to those with disturbances in FGF signaling. Accordingly, we looked at the effects of ph2alpha expression upstream and downstream of the FGF pathway. Treatment with SU5402, an inhibitor of Fgfrs, or injection of dominant-negative Fgfr1 DNA markedly reduced ph2alpha expression in the tailbud. In addition, cells expressing mRNAs for no tail, spadetail, myoD, and papc, which are involved in FGF-related development of posterior mesoderm, were distributed abnormally. Collectively, the data argue that ph2alpha is required for epiboly and tailbud formation, acting downstream of the FGF signaling pathway.     

Prolactin induces MFG-E8 production in macrophages via transcription factor C/EBPβ-dependent pathway

The lactogenic hormone prolactin (PRL) regulates milk protein gene expression in mammary glands. To maintain homeostatic balance in the body, milk fat globule epidermal growth factor 8 (MFG-E8) is vital for phagocytic clearance of apoptotic cells. We investigated the effects of PRL on MFG-E8 expression in macrophages by evaluating its promoter function. Macrophages were stimulated with PRL, and the expression of MFG-E8 was determined using real-time PCR and Western blotting. The role of MFG-E8 on phagocytosis of apoptotic cells in PRL-treated macrophages was assessed using microscopy, while the response of PRL to MFG-E8 expression was evaluated using luciferase assay. Following treatment with PRL, significant up-regulations of the PRL receptor and MFG-E8 were observed in macrophages, though PRL-treated macrophages more efficiently engulfed apoptotic cells. The results of MFG-E8 promoter analysis showed considerable up-regulation of promoter activity in macrophages following PRL treatment and results from mutation analysis of the MFG-E8 promoter suggested that the C/EBPβ binding site was responsible for PRL-induced activation of the MFG-E8 promoter. C/EBPβ activity was found to be up-regulated in PRL-treated cells as revealed by an electrophoretic mobility shift assay (EMSA). In conclusion, PRL is a potent inducer of MFG-E8 expression in macrophages, while its effect is mediated by the presence of a responsive element in the MFG-E8 promoter.