Induction of body distension by operations on the nervous system in larvae of the swallowtall, Papilio xuthus

Removal of the ganglion or severance of the nerve cords at the thorax in mature larvae of the swallowtail, Papilio xuthus, induced systemic distension of the body by swallowing excess air. Such a distension, however, was never induced by simultaneous extirpation of the brain, suboesophageal ganglion, or frontal ganglion, or by severance of the recurrent nerve. Removal of an abdominal ganglion induced distension of the posterior part of the body accompanied by shrinkage of the anterior part. The latter phenomenon appears to be induced by a different mechanism from that of systemic distension.     

CYCLIC NUCLEOTIDE PHOSPHODIESTERASE OF HUMAN CEREBROSPINAL FLUID

Abstract— Cyclic 3',5'-AMP (cAMP) and cyclic 3',5'–GMP (cGMP) phosphodiesterase activities were found in human cerebrospinal fluid (CSF) using low substrate concentration (0.4μM). More rapid hydrolysis of cGMP than that of cAMP was observed in human CSF. However, cGMP hydrolytic activity of CSF was very much lower (0.3 pmol/min/ml CSF) than that of human cerebral cortex (33.7 nmol/min/g wet cortex). The pH optimum was found to be 8.0 (cGMP phosphodiesterase) and 7.5 (cAMP phosphodiesterase). The maximum stimulation of both cAMP and cGMP phosphodiesterase was achieved at 4 mM-MgCl₂. Cyclic AMP had relatively little effect on the hydrolysis of cGMP in CSF and the cortex, while cGMP inhibited hydrolysis of cAMP in both tissues. Snake venom was found to stimulate cAMP and cGMP phosphodiesterase activity of CSF, by 60% and 110% respectively. This stimulation by snake venom was also observed in the cortex phosphodiesterase, but was not observed in human plasma or thyroid phosphodiesterase. When CSF was applied to Sepharose 6B column, cGMP phosphodiesterase was separated into three different molecular forms. A plot of activity against substrate concentration using peak I (largest molecular size) revealed a high affinity ( K _m= 2.6μM) and a low affinity ( K _m= 100μM) for cAMP suggesting the existence of at least two molecular forms of the enzyme. On the other hand, using a cGMP as substrate the only one K _m value (1.90 μm) was obtained. These K _m values of CSF enzymes described above were close to those obtained from human cerebral cortex preparations. The enzyme under peak I corresponded to the cortex enzyme when judged from its molecular size and stimulation by snake venom. It seems likely from our results that at least a part of CSF phosphodiesterase originates from the central nervous system.     

Tanycyte absorption affected by the hypothalamic deafferentation in Japanese quail,Coturnix coturnix japonica

In Japanese quail, Coturnix coturnix japonica the tanycytes of the median eminence absorbed peroxidase injected into the third ventricle. The number of tanycytes showing peroxidase reaction was greater in the posterior median eminence than in the anterior median eminence. Following hypothalamic deafferentation, the tanycyte absorption was augmented both in the posterior and anterior median eminence. These findings suggest that axons of some neurons, which have inhibitory action on the tanycyte absorption, were transected by deafferentation resulting in augmentation of tanycyte absorption. A considerable number of ependymal cells lining the upper portion of the third ventricle and those of the pars nervosa also absorbed peroxidase. In birds with a deafferented hypothalamus, photostimulated ovarian growth was completely inhibited.     

Cryopreservation of hairy root cultures of Vinca minor (L.) by encapsulation-dehydration

Hairy root cultures of Vinca minor and Ajuga reptans var. atropurpurea could be cryopreserved when the roots were precultured and encapsulated in 2% (w/v) alginate beads with 0.3 M sucrose and 0.5 M glycerol and dehydrated until the bead weight reached 25% of the initial weight before cooling in liquid nitrogen. Preculture and encapsulation of the roots with abscisic acid was effective in increasing the survival rates. For V. minor root tips moreover a sufficiently high survival rate of more than 70% was attained by eliminating glycerol from the preculture medium and dehydration of beads until 23% of the initial weight was reached instead of 25%.     

The Arabidopsis Protein SHI Represses Gibberellin Responses in Arabidopsis and Barley

The current model of gibberellin (GA) signal transduction is based on a derepressible system and a number of candidate negative regulators have been identified in Arabidopsis. We previously have reported the identification of the Arabidopsis gene SHORT INTERNODES (SHI) that causes suppression of GA responses when constitutively activated. In this paper, we show by using reporter gene analysis that the SHI gene is expressed in young organs, e.g. shoot apices and root tips. The model predicts a suppressor of GA responses to be active in these tissues to prevent premature growth or development. To study the effect of SHI on GA signaling, we used a functional assay that measures effects of signaling components on a well-defined GA response; the up-regulation of alpha-amylase in barley (Hordeum vulgare) aleurones in response to GA treatment. We found that SHI was able to specifically block the activity of a high-isoelectric point alpha-amylase promoter following GA(3) treatment, which further supports that SHI is a suppressor of GA responses. We have identified two putative loss-of-function insertion alleles of SHI and lines homozygous for either of the new alleles show no phenotypic deviations from wild type. Because SHI belongs to a gene family consisting of nine members, we suggest that SHI and the SHI-related genes are functionally redundant. We also show that a functional ERECTA allele is able to partly suppress the dwarfing effect of the shi gain-of-function mutation, suggesting that the erecta mutation harbored by the Landsberg erecta ecotype is an enhancer of the shi dwarf phenotype.     

Physicochemical properties and in vitro intestinal permeability properties and intestinal cell toxicity of silica particles,performed in simulated gastrointestinal fluids

Background

Amorphous silica particles with the primary dimensions of a few tens of nm, have been widely applied as additives in various fields including medicine and food. Especially, they have been widely applied in powders for making tablets and to coat tablets. However, their behavior and biological effects in the gastrointestinal tracts associated with oral administration remains unknown.

Methods

Amorphous silica particles with diameters of 50, 100, and 200 nm were incubated in the fasted-state and fed-state simulated gastric and intestinal fluids. The sizes, intracellular transport into Caco-2 cells (model cells for intestinal absorption), the Caco-2 monolayer membrane permeability, and the cytotoxicity against Caco-2 cells were then evaluated for the silica particles.

Results

Silica particles agglomerated in fed-state simultaneous intestinal fluids. The agglomeration and increased particles size inhibited the particles' absorption into the Caco-2 cells or particles' transport through the Caco-2 cells. The in vitro cytotoxicity of silica particles was not observed when the average size was larger than 100 nm, independent of the fluid and the concentration.

Conclusion

Our study indicated the effect of diet on the agglomeration of silica particles. The sizes of silica particles affected the particles' absorption into or transport through the Caco-2 cells, and cytotoxicity in vitro, depending on the various biological fluids.

General significance

The findings obtained from our study may offer valuable information to evaluate the behavior of silica particles in the gastrointestinal tracts or safety of medicines or foods containing these materials as additives.