Cloning and characterization of integrin alpha subunits from the solitary ascidian, Halocynthia roretzi

Recent molecular and biochemical analysis has revealed the presence of an opsonic complement system in the solitary ascidian, Halocynthia roretzi, composed of at least C3, two mannan binding protein-associated serine proteases, and factor B. To elucidate further the structure and function of this apparently primitive complement system in the urochordates, we looked for the ascidian complement receptor type 3 (CR3), or type 4 (CR4), which are members of the leukocyte integrin family in mammals. Using degenerate primers, we isolated two integrin alpha subunits (alpha(Hr1) and alpha(Hr2)) from the hemocyte mRNA of H. roretzi, by RT-PCR, and the entire coding sequence of alpha(Hr1) was determined from cDNA clones. alpha(Hr1) contains an I domain, the inserted domain characteristic of a subset of mammalian alpha subunits, including the leukocyte integrin family. A phylogenetic tree constructed for the alpha subunits also supports the ancestral position of alpha(Hr1) in the monophyletic cluster of I domain-containing alpha integrins. The alpha(Hr1) gene shows hemocyte-specific expression on Northern blot analysis. Western blot analysis and immunocytochemical staining of the hemocytes of H. roretzi using anti-alpha(Hr1) Ab showed that alpha(Hr1) subunits exist on the surface of a subpopulation of phagocytic hemocytes. Furthermore, anti-alpha(Hr1) Ab inhibited C3-dependent phagocytosis, but not basic phagocytosis, of yeast cells by ascidian hemocytes. These observations strongly suggest that alpha(Hr1) constitutes an integrin molecule on the hemocytes of H. roretzi that functions as an ancestral form of CR3 and CR4 and mediates phagocytosis in the primitive complement system of the ascidian.     

Behavior and distribution of upstream-migrating juvenilerhinogobius sp. (The orange form)

Upstream-migration of juvenileRhinogobius sp. OR was studied along the Ado River, a tributary of Lake Biwa. Juvenile gobies, mainly 18–21 mm in standard length, migrated from the lake in a belt of about 3 m wide in lower reaches and about 10–20 cm wide in middler reaches. Their upstream-migration was restricted to places shallower than 20 cm with bottom current velocities less than 20 cm/sec. Individual migration speed varied between 4.2–8.9 m/min at places with bottom current velocity of 8.8–20.0 cm/sec, slowing down with increasing current velocity. Most active migration occurred between 14:00 and 16:00, number of upstream-migrating juveniles decreasing with distance from the river mouth. Riffles in the mid-and upper reaches, having few slow current areas, probably present barriers to upstream-migration of the juvenile gobies, although both adults and subadults of the species are distributed in more upper reaches.     

A comprehensive test for negative frequency-dependent selection

Understanding the mechanisms that maintain genetic diversity within a population remains a primary challenge for evolutionary biology. Of the processes capable of maintaining variation, negative frequency-dependent selection (NFDS), under which rare phenotypes (or alleles) enjoy a high fitness advantage, is suggested to be the most powerful. However, few experimental studies have confirmed that this process operates in nature. Although a lot of suggestive evidence has separately been provided in various polymorphic systems, these are not enough to prove the existence of NFDS in each system. Here we present a general review of NFDS and point out some problems with previous works to develop reasonable alternative research strategies for testing NFDS. In the second half of this paper, we focused on NFDS in the common bluetail damselfly, Ischnura senegalensis, that shows female-limited genetic polymorphism. We show (1) the proximate causal mechanisms of the frequency-dependent process, (2) frequency-dependent inter-morph interaction, (3) rare morph advantage and (4) morph frequency oscillations in a natural population. These results provide unequivocal empirical support for NFDS in a natural system.     

Recombinant human thioredoxin-1 becomes oxidized in circulation and suppresses bleomycin-induced neutrophil recruitment in the rat airway

Thioredoxin-1 (TRX) is a redox-active protein with anti-inflammatory effects. This study investigated the optimal delivery method and the mechanisms of recombinant human TRX (rhTRX) to suppress neutrophil recruitment in a rat bleomycin (BLM)-induced sustained acute lung injury model. In male Wister rats intratracheally administered with 0.125 mg/kg BLM, 8 mg/kg/day rhTRX was intravenously administered on days 3–6 using one of three protocols: daily bolus injection, 3 h daily infusion or continuous infusion for 96 h. Only the continuous-infusion of rhTRX significantly reduced the neutrophil infiltration compared with the other two methods. The BLM-induced down-regulation of l-selectin expression on circulating neutrophils was inhibited by rhTRX. Oxidized rhTRX showed a comparable effect with reduced rhTRX and rhTRX incubated with plasma or circulating in plasma was more than 99% oxidized. These results suggest that rhTRX becomes oxidized in circulation and continuous infusion of rhTRX suppresses neutrophil recruitment in the airway.     

Kinetics and localisation of haemin-induced lipoprotein oxidation

Abstract

Haemin (iron (III)-protoporphyrin IX) is a degradation product of haemoglobin in circulating erythrocytes. Haemin may play a key oxidising agent for lipoprotein oxidation in patients with haemolytic anaemia. In this study, kinetic changes in chemical composition and target sites of haemin-induced LDL and HDL oxidation were investigated. Haemin initially induced the loss of α-tocopherol, followed by accumulation of lipid hydroperoxide (LP) and alteration of core lipid fluidity. The absence of LP in HDL was explained by the antioxidant activity of PON in addition to α-tocopherol. The target site of haemin was evaluated by ESR spin labelling with 5- and 16-doxyl steric acids. In the presence of t-BuOOH and haemin, ESR signal decay of the doxyl moiety demonstrated the initiation phase and the propagation phase of lipid peroxidation. The results of the lag time and the rate of signal decay indicated that haemin is located near the 16th carbon atom of the fatty acid chain in the phospholipid layer. The analyses of motion parameters, order parameter (S) of 5-DS and rotational correlation time (τ) of 16-DS, supported the observation that the lipid properties changed near the hydrophobic region rather than at the surface region of lipoproteins. Moreover, ESR spin labelling demonstrated that haemin molecules but not iron ions caused lipoprotein oxidation. In conclusion, haemin is a potent inducer of lipoprotein oxidation, and the target site for this oxidation is near the hydrophobic core of the lipoprotein leading to the loss of antioxidant activities and changes in lipid composition and physical properties.     

Speciation along a latitudinal gradient: The origin of the Neotropical cycad sister pair Dioon sonorense–D. vovidesii (Zamiaceae)

Latitude is correlated with environmental components that determine the distribution of biodiversity. In combination with geographic factors, latitude‐associated environmental variables are expected to influence speciation, but empirical evidence on how those factors interplay is scarce. We evaluated the genetic and environmental variation among populations in the pair of sister species Dioon sonorense–D. vovidesii, two cycads distributed along a latitudinal environmental gradient in northwestern Mexico, to reveal their demographic histories and the environmental factors involved in their divergence. Using genome‐wide loci data, we determined the species delimitation, estimated the gene flow, and compared multiple demographic scenarios of divergence. Also, we estimated the variation of climatic variables among populations and used ecological niche models to test niche overlap between species. The effect of geographic and environmental variables on the genetic variation among populations was evaluated using linear models. Our results suggest the existence of a widespread ancestral population that split into the two species ~829 ky ago. The geographic delimitation along the environmental gradient occurs in the absence of major geographic barriers, near the 28th parallel north, where a zonation of environmental seasonality exists. The northern species, D. vovidesii, occurs in more seasonal environments but retains the same niche of the southern species, D. sonorense. The genetic variation throughout populations cannot be solely explained by stochastic processes; the latitudinal‐associated seasonality has been an additive factor that strengthened the species divergence. This study represents an example of how speciation can be achieved by the effect of the latitude‐associated factors on the genetic divergence among populations.     

The association between circadian rest-activity patterns and the behavioral and psychological symptoms depending on the cognitive status in Japanese nursing-home residents

ABSTRACT

Background: Limited information is available on the relationship between sleep disturbances during nighttime and the behavioral and psychological symptoms of dementia in older nursing-home residents. However, a few reports on the association between the circadian rest-activity rhythm and the behavioral and psychological symptoms of dementia in older residents have been published. The main objective of the present study was to examine the association among the circadian rest-activity rhythm, behavioral and psychological symptoms, and the cognitive function status among older individuals living in facilities. Method: The investigation was conducted from September 2017 to February 2018, and participants were recruited from five nursing homes in Akita prefecture, Japan, after obtaining patient agreement to participate in the study. To measure nonparametric circadian rest-activity parameters such as interdaily stability, intradaily variability, relative amplitude, mean of the least active 5-h period, and mean of the most active 10-h period, Actigraph devices were worn on the participants’ nondominant wrists continuously for seven days. The score or classification of the cognitive status and the severity of the behavioral and psychological symptoms of dementia (BPSD) were assessed using the clinical dementia rating (CDR) and the dementia behavior disturbance scale (DBD), respectively. The binomial logistic regression model was applied to clarify which kinds of circadian rest-activity parameters predicted the cognitive status in nursing home residents as well as the BPSD outcome. A multi-level model was also used to examine the association between the nonparametric rest-activity parameters and the BPSD outcome explained by the cognitive status among older individuals in facilities. Results: Seventy-seven participants (49 residents with dementia, and 28 residents without dementia) were included in this study. According to the binomial logistic regression analysis after adjusting for covariates, the classification of the cognitive status for older residents was associated with the DBD score (odds ratio, 1.22; 95% confidence interval [CI], 1.08, 1.38; p < 0.001), the IS (odds ratio, 0.01; 95% CI, 0.00, 1.00; p = 0.05) and the L5 (odds ratio, 0.99; 95% CI, 0.99, 1.00; p = 0.05). The results of a multi-level model also indicated that the IV at individual-level was significantly associated with the DBD score for nursing home residents, with the CDR score at cluster-level as an explanatory variable. As well, a significant association between the RA at individual level and the DBD score was observed in a multi-level model explained by the CDR score at cluster-level. Conclusion: Of these models, the multi-level model provided grounds for our proposal that the fragmentation or the amplitude of rest-activity parameters might be associated with the outcome of BPSD, considering the cognitive status of older individuals in different facilities. The findings offer practical insight into the prevention of BPSD and the improvement of rest-activity rhythms in rehabilitative care in nursing homes.     

Anti-Influenza Activity of C60 Fullerene Derivatives

The H1N1 influenza A virus, which originated in swine, caused a global pandemic in 2009, and the highly pathogenic H5N1 avian influenza virus has also caused epidemics in Southeast Asia in recent years. Thus, the threat from influenza A remains a serious global health issue, and novel drugs that target these viruses are highly desirable. Influenza A RNA polymerase consists of the PA, PB1, and PB2 subunits, and the N-terminal domain of the PA subunit demonstrates endonuclease activity. Fullerene (C₆₀) is a unique carbon molecule that forms a sphere. To identify potential new anti-influenza compounds, we screened 12 fullerene derivatives using an in vitro PA endonuclease inhibition assay. We identified 8 fullerene derivatives that inhibited the endonuclease activity of the PA N-terminal domain or full-length PA protein in vitro. We also performed in silico docking simulation analysis of the C₆₀ fullerene and PA endonuclease, which suggested that fullerenes can bind to the active pocket of PA endonuclease. In a cell culture system, we found that several fullerene derivatives inhibit influenza A viral infection and the expression of influenza A nucleoprotein and nonstructural protein 1. These results indicate that fullerene derivatives are possible candidates for the development of novel anti-influenza drugs.