Quadrupedal Walking with the Skin: The Ambulatory Flaps in "Walking" Cuttlefish (Paintpot Cuttlefish, Metasepia tullbergi).

AbstractThe locomotion strategy of cephalopods is an important factor that influences their ability to exploit various oceanic environments. Particularly, Metasepia cuttlefish have a unique locomotion strategy; they prefer slow walking (ambling) on the seafloor over swimming. For this locomotion, they use their ventral arms as forelimbs and ambulatory flaps as hindlimbs. This locomotion is similar to the gait of quadruped vertebrates, where the forelimbs and hindlimbs on the left and right move alternately. The original description and some textbooks have considered these flaps to be muscular; however, this has not been proven. Here, we report the histological morphology of the ambulatory flaps of Metasepia tullbergi and their ambling locomotion. Histological observations indicated that the ambulatory flaps had a papillae structure comprising papillae musculature (dermal erector or retractor muscles) and connective tissue in the skin. Behavioral observations indicated that the ambulatory flaps changed their shape during ambling, which could explain the existence of the skin papillae. Our results suggest that ambulatory flaps are skin papillae, which can change shape by using their papillae musculature and connective tissue. This is a unique feature of Metasepia species that use the skin papillae for locomotion.

Amino acid activation analysis of primitive aminoacyl-tRNA synthetases encoded by both strands of a single gene using the malachite green assay.

The Rodin-Ohno hypothesis postulates that two classes of aminoacyl-tRNA synthetases were encoded complementary to double-stranded DNA. Particularly, Geobacillus stearothermophilus tryptophanyl-tRNA synthetase (TrpRS, belonging to class I) and Escherichia coli histidyl-tRNA synthetase (HisRS, belonging to class II) show high complementarity of the middle base of the codons in the mRNA sequence encoding each ATP binding site. Here, for the reported 46-residue peptides designed from the three-dimensional structures of TrpRS and HisRS, amino acid activation analysis was performed using the malachite green assay, which detects the pyrophosphate departing from ATP in the forward reaction of the first step of tRNA aminoacylation. A maltose-binding protein fusion with the 46 residues of TrpRS (TrpRS46mer) exhibited high activation capacity for several amino acids in the presence of ATP and amino acids, but the activity of an alanine substitution mutant of the first histidine in the HIGH motif (TrpRS46merH15A) was largely reduced. In contrast, pyrophosphate release by HisRS46mer in the histidine activation step was lower than that in the case of TrpRS46mer. Both HisRS46mer and the alanine mutant at the 113th arginine (HisRS46merR113A) showed slightly higher levels of pyrophosphate release than the maltose-binding protein alone. These results do not rule out the Rodin-Ohno hypothesis, but may suggest the necessity of establishing unique evolutionary models from different perspectives.

Correction to: G:U­Independent RNA Minihelix Aminoacylation by Nanoarchaeum equitans Alanyl­tRNA Synthetase: An Insight into the Evolution of Aminoacyl­tRNA Synthetases.

In the original version of this article, "A73" in Fig 6b was inadvertently labeled as "G73". The corrected Fig. 6 is given here.

G:U-Independent RNA Minihelix Aminoacylation by Nanoarchaeum equitans Alanyl-tRNA Synthetase: An Insight into the Evolution of Aminoacyl-tRNA Synthetases.

Nanoarchaeum equitans is a species of hyperthermophilic archaea with the smallest genome size. Its alanyl-tRNA synthetase genes are split into AlaRS-α and AlaRS-ß, encoding the respective subunits. In the current report, we surveyed N. equitans AlaRS-dependent alanylation of RNA minihelices, composed only of the acceptor stem and the T-arm of tRNAAla. Combination of AlaRS-α and AlaRS-ß showed a strong alanylation activity specific to a single G3:U70 base pair, known to mark a specific tRNA for charging with alanine. However, AlaRS-α alone had a weak but appreciable alanylation activity that was independent of the G3:U70 base pair. The shorter 16-mer RNA tetraloop substrate mimicking only the first four base pairs of the acceptor stem of tRNAAla, but with C3:G70 base pair, was also successfully aminoacylated by AlaRS-α. The end of the acceptor stem, including CCA-3' terminus and the discriminator A73, was able to function as a minimal structure for the recognition by the enzyme. Our findings imply that aminoacylation by N. equitans AlaRS-α may represent a vestige of a primitive aminoacylation system, before the appearance of the G3:U70 pair as an identity element for alanine.

Neurite outgrowth of PC12 cells on diX (parylene) family materials.

We investigated neuronal cell differentiation, particularly neurite outgrowth, on the surface of diX H and diX AM using an in vitro examination of a neuron-like rat pheochromocytoma cell line, PC12. diX H and diX AM are in the parylene family of diX C (or Parylene-C), which is widely used as a novel coating material to insulate neural electrodes, and they have been recently commercialized; diX H and diX AM offer different features of biocompatibility. Previously, we found that these new parylene materials have high cell adhesiveness to neuronal cells whereas the adhesiveness of diX C is extremely low. However, their cell differentiation remains unknown although neuronal cell differentiation plays a crucial role in their development and regeneration. This study showed that almost all PC12 cells adhering to the surface of diX AM and diX H were differentiated, but the neurite outgrowth was significantly larger on diX H than that on diX AM and a conventional polystyrene culture dish. The result suggests that diX H may be advantageous as a biocompatible coating material for a scaffold, which can be used on virtually any substrate to get various configurations in neural devices.

Hippocampal theta rhythm and drug-related reward-seeking behavior: an analysis of cocaine-induced conditioned place preference in rats.

Drug cravings are elicited by environmental stimuli associated with the rewarding effects of drugs. As an animal model of such associative learning, conditioned place preference (CPP) is widely used. Since the hippocampus is closely related to reward memory and the hippocampal local field potential (LFP), and in particular the theta rhythm is known to be associated with bodily movements, the theta rhythm might be one of the key neural substrates. On the basis of this assumption, we recorded the behaviors and hippocampal LFP of eight rats during cocaine-induced acquisition and expression of CPP. The earliest appearance of phase-locked theta activity was observed before the rats entered the cocaine-paired environment after conditioning; after entrance, the theta disappeared. This phase-locked theta was stronger when the rats stayed for a long time in the cocaine-paired environment. Our observation suggested that the phase-locked hippocampal theta rhythm is related to the approaching behavior of the rat caused by reward memory. Thus, the role of the hippocampus in drug craving should be emphasized further.

[Dietary life style of Japanese college students: relationship between dietary life, mental health and eating disorders].

A scale was constructed to investigate the dietary life style of Japanese college students relating to dietary life, mental health, and eating disorders. Exploratory factor analysis found four factors, termed "dietary mood," "dietary regulation," "dietary stress avoidance behavior," and "food safety." Cluster analysis revealed four typical dietary habits of Japanese college students: "deprecating food safety," "dietary regulation oriented and infrequent dietary stress avoidance behavior," "deprecating dietary moods," and "frequent dietary stress avoidance behavior." Regarding eating disorders, a high percentage of the moderate eating disorder group exhibited frequent dietary stress avoidance behavior. Regarding mental health, a high percentage of the healthy group showed dietary regulation orientation and infrequent dietary stress avoidance behavior. A high percentage of the neurotic-level participants deprecated dietary moods. These results suggest that dietary regulation and deprecatory mood and infrequent dietary stress avoidance behavior lead to college students having a healthy dietary life.

Comparison of neuronal cell adhesiveness of materials in the diX (Parylene) family.

DiX C (or Parylene-C) has been widely used as a coating material to insulate neural electrodes in recent decades. However, its uses are limited due to its extremely low adhesiveness with neuronal cells. Other functional materials in the diX family, such as diX A, diX AM, and diX H, have been commercialized recently and would offer different features in biocompatibility from diX C. However, their cell adhesiveness remains unknown. In this work, we used an in vitro approach to investigate how the surface of each material in the diX family affects the degree of neuronal cell adhesiveness compared with a conventional culture dish of polystyrene (PS). The neuronal cell adhesiveness on diX AM and diX H was almost equivalent to that for the PS dish, whereas neuronal cells did not settle on the surface of diX C and diX A. Our results suggest that diX AM and diX H could provide another practical feature as a coating material for a scaffold in a substrate with any configuration in neural devices.