Design, synthesis and characterization of podocarpate derivatives as openers of BK channels

We found that the podocarpic acid structure provides a new scaffold for chemical modulators of large-conductance calcium-activated K(+) channels (BK channels). Structure-activity analysis indicates the importance of both the arrangement (i.e., location and orientation) of the carboxylic acid functionality of ring A and the hydrophobic region of ring C for expression of BK channel-opening activity.     

Revision of the genus Stichillus Enderlein of Japan (Diptera: Phoridae)

The genus Stichillus in Japan is revised. Three species are recognized: S. japonicus (Matsumura), S. spinosus Liu and Chou and S. cylindratus sp. nov. Stichillus brunneicornis Beyer is excluded from the Japanese fauna. These Japanese species are described and keyed. The male genitalia and the female terminalia are illustrated. Some unique characters of the male genitalia in the genus are reported, and morphology of the male genitalia and the female terminalia is discussed.     

Mutation in keratin 18 induces mitochondrial fragmentation in liver-derived epithelial cells

Microtubules (MTs) and microfilaments (MFs) are known to modulate mitochondrial morphology, distribution and function. However, little is known evidence about the role of intermediate filaments (IFs) in modulating mitochondria except desmin. To investigate whether or not the IFs regulate mitochondrial morphology, distribution, and function, we manipulated the IFs of cultured epithelial cells to express a mutant keratin 18 (K18). In contrast to the filamentous expression of wild K18, mutant K18 induced aggregation of K8/18, showing no fine IF network in the cells. In mutant K18-transfected cells, the mitochondria were fragmented into small spheroids, although they were observed as mitochondrial fibers in un-transfected or wild K18-transfected cells. Fluorescence recovery after photobleaching of fluorescence-labeled mitochondria was markedly less in the mutant K18-transfected cells, although a significant recovery was confirmed in wild K18-transfected cells. These findings suggest that the IFs are important for the maintenance of normal mitochondrial structures.     

Spike‐triggered dendritic calcium transients depend on synaptic activity in the cricket giant interneurons

The relationship between electrical activity and spike‐induced Ca²⁺ increases in dendrites was investigated in the identified wind‐sensitive giant interneurons in the cricket. We applied a high‐speed Ca²⁺ imaging technique to the giant interneurons, and succeeded in recording the transient Ca²⁺ increases (Ca²⁺ transients) induced by a single action potential, which was evoked by presynaptic stimulus to the sensory neurons. The dendritic Ca²⁺ transients evoked by a pair of action potentials accumulated when spike intervals were shorter than 100 ms. The amplitude of the Ca²⁺ transients induced by a train of spikes depended on the number of action potentials. When stimulation pulses evoking the same numbers of action potentials were separately applied to the ipsi‐ or contra‐lateral cercal sensory nerves, the dendritic Ca²⁺ transients induced by these presynaptic stimuli were different in their amplitude. Furthermore, the side of presynaptic stimulation that evoked larger Ca²⁺ transients depended on the location of the recorded dendritic regions. This result means that the spike‐triggered Ca²⁺ transients in dendrites depend on postsynaptic activity. It is proposed that Ca²⁺ entry through voltage‐dependent Ca²⁺ channels activated by the action potentials will be enhanced by excitatory synaptic inputs at the dendrites in the cricket giant interneurons. © 2002 Wiley Periodicals, Inc. J Neurobiol 50: 234–244, 2002; DOI 10.1002/neu.10032     

Spike-triggered dendritic calcium transients depend on synaptic activity in the cricket giant interneurons.

The relationship between electrical activity and spike-induced Ca2+ increases in dendrites was investigated in the identified wind-sensitive giant interneurons in the cricket. We applied a high-speed Ca2+ imaging technique to the giant interneurons, and succeeded in recording the transient Ca2+ increases (Ca2+ transients) induced by a single action potential, which was evoked by presynaptic stimulus to the sensory neurons. The dendritic Ca2+ transients evoked by a pair of action potentials accumulated when spike intervals were shorter than 100 ms. The amplitude of the Ca2+ transients induced by a train of spikes depended on the number of action potentials. When stimulation pulses evoking the same numbers of action potentials were separately applied to the ipsi- or contra-lateral cercal sensory nerves, the dendritic Ca2+ transients induced by these presynaptic stimuli were different in their amplitude. Furthermore, the side of presynaptic stimulation that evoked larger Ca2+ transients depended on the location of the recorded dendritic regions. This result means that the spike-triggered Ca2+ transients in dendrites depend on postsynaptic activity. It is proposed that Ca2+ entry through voltage-dependent Ca2+ channels activated by the action potentials will be enhanced by excitatory synaptic inputs at the dendrites in the cricket giant interneurons.     

Absence of amylose in sweet potato [Ipomoea batatas (L.) Lam.] following the introduction of granule-bound starch synthase I cDNA

The full-length sense cDNA for sweet potato granule-bound starch synthase I (GBSSI) driven by the CaMV 35S promoter was introduced into the sweet potato by Agrobacterium tumefaciens-mediated transformation. Out of the 26 transgenic plants obtained, one plant showed the absence of amylose in the tuberous root as determined by the iodine colorimetric method. Electrophoresis analysis failed to detect the GBSSI protein, suggesting that gene silencing of the GBSSI gene occurred in the transgenic sweet potato plant. These results demonstrate that starch composition in the tuberous root of sweet potato can be altered by genetic transformation.     

Little or no induction of hyperglycemia by 2-deoxy-D-glucose in hereditary blind microphthalmic rats

Studies were made on whether hereditary microphthalmic rats (1), which are congenitally blind, showed a hyperglycemic response to intracerebroventricular injection of 2-deoxy-D-glucose (2DG) in their subjective light period. In contrast to previous findings in normal rats in which 2DG injection caused light-cycle dependent hyperglycemia (2) and bilateral lesion of the suprachiasmatic nucleus (SCN) completely abolished this hyperglycemia (3), 2DG injection caused no and only slight hyperglycemia in male and female rats with hereditary microphthalmia, respectively. Gross and histological examinations indicated that these rats had no optic nerve or retinohypothalamic tract and that their SCN had an abnormal structure. Locomotive activity recordings showed that all the blind rats had a free-running circadian activity rhythm. These findings suggest that the projection sites of the retinohypothalamic tract to the SCN are involved in the mechanism of the hyperglycemic response to 2DG, but that neural cells, which may be responsible for the generation of circadian rhythms, are not. We have reported that when adult rats were blinded by orbital enucleation, their hyperglycemic response to 2DG was suppressed temporarily 3-5 weeks after the operation, but that their plasma insulin level was basically higher and increased further after 2DG injection during this period (4). In congenitally blind rats, however, the basal plasma insulin level was not higher and the level did not change after 2DG treatment. This difference is discussed from the view point of the role of the premature SCN in regulation of the plasma insulin concentration.     

The ethmoid and presphenoid of cetaceans

A cribriform plate, a perpendicular plate, and two lateral masses are major components of the ethmoid bone of mammals. Notwithstanding the noticeable bone, virtually sitting in the center of the skull, extensive modifications of the skull of modern cetaceans, especially odontocetes (toothed whales), and the lack of clarity as to what characteristics delimit each element of the ethmoid has made the problem of the nature of the cetacean ethmoid more complicated and elusive than in other, less modified mammals. Furthermore, contention as to whether a perpendicular plate of the ethmoid, or the mesethmoid, exists in all mammals including cetaceans has remained unsettled. In odontocetes, the mesethmoid has been variably identified not only as the osseous nasal septum but also as the mediodorsal region of the posterior wall of the nasal passage below the nasals, as a mass of bone encased by the vomer in front of the osseous nasal cavity at the base of the rostrum, and as a combination of some portions mentioned above. The presence or absence of the mesethmoid in various groups of mammals has attracted the attention of some biologists, and here, I demonstrate that cetaceans have no mesethmoid. The close inspection of the ontogenetic changes of the basicranial elements in cetaceans reveals that a mass of bone ensheathed by the vomer in front, or at the level of the osseous nasal cavity is actually the presphenoid. It is highly likely that in odontocetes the posterior wall of the nasal passages below the nasals consists of the combination of the frontal, the imperforated cribriform plate, the paired ectethmoids, and the vomer, the latter three of which partially concealing the presphenoid dorsally and laterally as the ontogeny proceeds. In contrast, mysticetes clearly display ethmoturbinates and a cribriform plate, which are morphologically similar to those in terrestrial mammals. J. Morphol. 277:1661–1674, 2016. © 2016 Wiley Periodicals, Inc.