Reproductive biology and genetic population structure of two alien Lolium species inhabiting the sandy coasts of Japan

Understanding the characteristics of alien species is a prerequisite for any biological study or anti-invasion management strategy. Lolium rigidum (Poaceae) is an alien species that has become naturalized on the sandy coasts of Japan; however, it exhibits extensive morphological variation, leading to speculation that several taxa of Lolium have become naturalized. Here, we compared the morphology, reproductive biology and genetic structure of this Lolium species by growing individuals from different locations in the same environment to clarify whether the observed morphological variation is genetically based or is caused by intraspecific variation as a result of environmental differences. Principle component analyses of 11 morphological traits separated the study species into two types. Bagging experiments showed that one type exhibited an outcrossing life history, whereas the other type selfed exclusively. Nuclear DNA microsatellite analyses supported this distinction between these morphological types, with no intermediate individuals being found. The outcrossing type exhibited high genetic diversity, whereas the selfing type exhibited almost no polymorphism, reflecting the differences in their breeding systems. Moreover, both types differed from the economically important outcrossing species Lolium multiflorum and Lolium perenne. These two types of Lolium are expected to have different introduction histories and invasive potential on the coasts of Japan. In conclusion, it is important to distinguish between these types through additional biological studies to design effective control measures.     

148 Life History and Feeding Preferences of Gallery-Forming Harpacticoids in Dictyotalean Seaweeds

The harpacticoid copepod Dactylopusioides macrolabris has been reported to make galleries beneath the cuticle of cortical cells of Dictyota dichotoma (Dictyotales, Phaeophyceae; Green 1958). Besides this species, we have found several more harpacticoids from Japanese coasts that have similar habits, infesting various dictyotalean species. In laboratory culture experiments growing the harpacticoids for several generations and recording their behaviors by interval video recoding, we have found that these harpacticoids spend most of the lives in the galleries, feeding only on the algal tissues. Different species showed different feeding preferences even among morphologically very close species: one species fed most of the dictyotalean species examined, whereas another species could digest only one species. In order to discuss the evolutionary interactions between the harpacticoids and host seaweeds, comparative molecular phylogenetic analyses of the harpacticoids and host seaweeds were studied using rDNA ITS2 (harpacticoids) and rbc L (Dictyotales) DNA sequences.     

SARS-CoV-2 spike L452R variant evades cellular immunity and increases infectivity

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Inhibitory neurons exhibit high controlling ability in the cortical microconnectome

The brain is a network system in which excitatory and inhibitory neurons keep activity balanced in the highly non-random connectivity pattern of the microconnectome. It is well known that the relative percentage of inhibitory neurons is much smaller than excitatory neurons in the cortex. So, in general, how inhibitory neurons can keep the balance with the surrounding excitatory neurons is an important question. There is much accumulated knowledge about this fundamental question. This study quantitatively evaluated the relatively higher functional contribution of inhibitory neurons in terms of not only properties of individual neurons, such as firing rate, but also in terms of topological mechanisms and controlling ability on other excitatory neurons. We combined simultaneous electrical recording (~2.5 hours) of ~1000 neurons in vitro, and quantitative evaluation of neuronal interactions including excitatory-inhibitory categorization. This study accurately defined recording brain anatomical targets, such as brain regions and cortical layers, by inter-referring MRI and immunostaining recordings. The interaction networks enabled us to quantify topological influence of individual neurons, in terms of controlling ability to other neurons. Especially, the result indicated that highly influential inhibitory neurons show higher controlling ability of other neurons than excitatory neurons, and are relatively often distributed in deeper layers of the cortex. Furthermore, the neurons having high controlling ability are more effectively limited in number than central nodes of k-cores, and these neurons also participate in more clustered motifs. In summary, this study suggested that the high controlling ability of inhibitory neurons is a key mechanism to keep balance with a large number of other excitatory neurons beyond simple higher firing rate. Application of the selection method of limited important neurons would be also applicable for the ability to effectively and selectively stimulate E/I imbalanced disease states.     

Positioning proton-donating residues to the Schiff-base accelerates the M-decay of pharaonis phoborhodopsin expressed in Escherichia coli.

Phoborhodopsin (also called sensory rhodopsin II, sR-II) is a receptor for the negative phototaxis of Halobacterium salinarum (pR), and pharaonis phoborhodopsin (ppR) is the corresponding receptor of Natronobacterium pharaonis. pR and ppR are retinoid proteins and have a photocycle similar to that of bacteriorhodopsin (bR). A major difference between the photocycle of the ion pump bR and the sensor pR or ppR is found in their turnover rates which are much faster for bR. A reason for this difference might be found in the lack of a proton-donating residue to the Schiff base which is formed between the lysine of the opsin and retinal. To reconstruct a bR-like photochemical behavior, we expressed ppR mutants in Escherichia coli in which proton-donating groups have been reintroduced into the cytoplasmic proton channel. In measurement of the photocycle it could be shown that the F86D mutant of ppR (Phe86 was substituted by Asp) showed a faster decay of M-intermediate than the wild-type, which was even accelerated in the F86D/L40T double mutant.     

Immunoadjuvant activities of synthetic 6-O-acyl-N-acetylmuramyl-L-alanyl-D-isoglutamine with special reference to the effect of its administration with liposomes

Addition of a lauroyl, stearoyl or docosanoyl group to the primary hydroxy group at the C-6 position of N-acetylmuramyl-L-alanyl-D-isoglutamine gave lipophilic derivatives that had definite adjuvancies in induction of delayed-type hypersensitivity and enhancement of antibody production against a test protein antigen, ovalbumin, when administered to guinea pigs as liposomes, that is without mineral oil. When administered as mineral oil-in-water emulsion, including Ribitype emulsions, rather than as water-in-mineral oil emulsions, N-acetylmuramyl-L-alanyl-D-isoglutamine and its 6-O-acyl derivatives showed only weak immunoadjuvancies.     

Distribution of 35S-taurine in rat neonates and adults

Summary The distribution of ³⁵S-taurine in rat neonates and adults was investigated by wholy-body autoradiography. The neonates (4-day-old) were frozen in dry-ice hexane at 30 min, 1, 3 and 6 h after an intraperitoneal injection of ³⁵S-taurine, whereas survival intervals for adult rats were 1 and 3 h. Whole-sagittal sections of the frozen rat, obtained by using a cryostat microtome were dried in situ and autoradiographed. In rat neonates and adults, ³⁵S-taurine was mainly accumulated in the renal cortex, urine, feces, liver, eye (lens, vitreous fluid, retina), hypophysis, thymus, adrenal glands, nasal mucous membrane, salivary glands, gastric mucosa, small and large intestinal mucosa, choroid plexus, myocardium and sebaceous glands. In the rat neonate, such regions as the olfactory bulb, cerebrum, and cerebellum showed relatively high optical density.