Ranging behavior of Mahale chimpanzees: a 16 year study

We have analyzed the ranging patterns of the Mimikire group (M group) of chimpanzees in the Mahale Mountains National Park, Tanzania. During 16 years, the chimpanzees moved over a total area of 25.2 or 27.4 km², as estimated by the grid-cell or minimum convex polygon (MCP) methods, respectively. Annually, the M group used an average of 18.4 km², or approximately 70 %, of the total home-range area. The chimpanzees had used 80 % of their total home range after 5 years and 95 % after 11 years. M group chimpanzees were observed more than half of the time in areas that composed only 15 % of their total home range. Thus, they typically moved over limited areas, visiting other parts of their range only occasionally. On average, the chimpanzees used 7.6 km² (in MCP) per month. Mean monthly range size was smallest at the end of the rainy season and largest at the end of the dry season, but there was much variability from year to year. The chimpanzees used many of the same areas every year when Saba comorensis fruits were abundant between August and January. In contrast, the chimpanzees used several different areas of their range in June. Here range overlap between years was relatively small. Over the 16 years of the study we found that the M group reduced their use of the northern part of their range and increased their frequency of visits to the eastern mountainous side of their home range. Changes in home-range size correlated positively with the number of adult females but not with the number of adult males. This finding does not support a prediction of the male-defended territory model proposed for some East African chimpanzee unit-groups.     

Structural Basis for the Different Stability and Activity between the Cdk5 Complexes with p35 and p39 Activators

Cyclin-dependent kinase 5 (Cdk5) is a brain-specific membrane-bound protein kinase that is activated by binding to the p35 or p39 activator. Previous studies have focused on p35-Cdk5, and little is known regarding p39-Cdk5. The lack of functional understanding of p39-Cdk5 is due, in part, to the labile property of p39-Cdk5, which dissociates and loses kinase activity in nonionic detergent conditions. Here we investigated the structural basis for the instability of p39-Cdk5. p39 and p35 contain N-terminal p10 regions and C-terminal Cdk5 activation domains (AD). Although p35 and p39 show higher homology in the C-terminal AD than the N-terminal region, the difference in stability is derived from the C-terminal AD. Based on the crystal structures of the p25 (p35 C-terminal region including AD)-Cdk5 complex, we simulated the three-dimensional structure of the p39 AD-Cdk5 complex and found differences in the hydrogen bond network between Cdk5 and its activators. Three amino acids of p35, Asp-259, Asn-266, and Ser-270, which are involved in hydrogen bond formation with Cdk5, are changed to Gln, Gln, and Pro in p39. Because these three amino acids in p39 do not participate in hydrogen bond formation, we predicted that the number of hydrogen bonds between p39 and Cdk5 was reduced compared with p35 and Cdk5. Using substitution mutants, we experimentally validated that the difference in the hydrogen bond network contributes to the different properties between Cdk5 and its activators.     

Photoreceptor Proteins Initiate Microglial Activation via Toll-like Receptor 4 in Retinal Degeneration Mediated by All-trans-retinal

Although several genetic and biochemical factors are associated with the pathogenesis of retinal degeneration, it has yet to be determined how these different impairments can cause similar degenerative phenotypes. Here, we report microglial/macrophage activation in both a Stargardt disease and age-related macular degeneration mouse model caused by delayed clearance of all-trans-retinal from the retina, and in a retinitis pigmentosa mouse model with impaired retinal pigment epithelium (RPE) phagocytosis. Mouse microglia displayed RPE cytotoxicity and increased production of inflammatory chemokines/cytokines, Ccl2, Il1b, and Tnf, after coincubation with ligands that activate innate immunity. Notably, phagocytosis of photoreceptor proteins increased the activation of microglia/macrophages and RPE cells isolated from model mice as well as wild-type mice. The mRNA levels of Tlr2 and Tlr4, which can recognize proteins as their ligands, were elevated in mice with retinal degeneration. Bone marrow-derived macrophages from Tlr4-deficient mice did not increase Ccl2 after coincubation with photoreceptor proteins. Tlr4^−/−Abca4^−/−Rdh8^−/− mice displayed milder retinal degenerative phenotypes than Abca4^−/−Rdh8^−/− mice. Additionally, inactivation of microglia/macrophages by pharmacological approaches attenuated mouse retinal degeneration. This study demonstrates an important contribution of TLR4-mediated microglial activation by endogenous photoreceptor proteins in retinal inflammation that aggravates retinal cell death. This pathway is likely to represent an underlying common pathology in degenerative retinal disorders.     

Endogenous abscisic acid is involved in methyl jasmonate-induced reactive oxygen species and nitric oxide production but not in cytosolic alkalization in Arabidopsis guard cells

We recently demonstrated that endogenous abscisic acid (ABA) is involved in methyl jasmonate (MeJA)-induced stomatal closure in Arabidopsis thaliana. In this study, we investigated whether endogenous ABA is involved in MeJA-induced reactive oxygen species (ROS) and nitric oxide (NO) production and cytosolic alkalization in guard cells using an ABA-deficient Arabidopsis mutant, aba2-2, and an inhibitor of ABA biosynthesis, fluridon (FLU). The aba2-2 mutation impaired MeJA-induced ROS and NO production. FLU inhibited MeJA-induced ROS production in wild-type guard cells. Pretreatment with 0.1 μM ABA, which does not induce stomatal closure in the wild type, complemented the insensitivity to MeJA of the aba2-2 mutant. However, MeJA induced cytosolic alkalization in both wild-type and aba2-2 guard cells. These results suggest that endogenous ABA is involved in MeJA-induced ROS and NO production but not in MeJA-induced cytosolic alkalization in Arabidopsis guard cells.     

Optically Detected Structural Change in the N-Terminal Region of?the?Voltage-Sensor Domain

The voltage-sensor domain (VSD) is a functional module that undergoes structural transitions in response to membrane potential changes and regulates its effectors, thereby playing a crucial role in amplifying and decoding membrane electrical signals. Ion-conductive pore and phosphoinositide phosphatase are the downstream effectors of voltage-gated channels and the voltage-sensing phosphatase, respectively. It is known that upon transition, the VSD generally acts on the region C-terminal to S4. However, whether the VSD also induces any structural changes in the N-terminal region of S1 has not been addressed directly. Here, we report the existence of such an N-terminal effect. We used two distinct optical reporters—one based on the Förster resonance energy transfer between a pair of fluorescent proteins, and the other based on fluorophore-labeled HaloTag—and studied the behavior of these reporters placed at the N-terminal end of the monomeric VSD derived from voltage-sensing phosphatase. We found that both of these reporters were affected by the VSD transition, generating voltage-dependent fluorescence readouts. We also observed that whereas the voltage dependencies of the N- and C-terminal effects appear to be tightly coupled, the local structural rearrangements reflect the way in which the VSD is loaded, demonstrating the flexible nature of the VSD.     

Utilization of Alcohols by Rhodopseudomonas sp. No. 7 Isolated from n-Propanol–Enrichment Cultures

A purple non-sulfur bacterium, Rhodopseudomonas sp. No. 7, was isolated from n-propanol–enrichment cultures under anaerobic-light conditions. Strain No. 7 can produce hydrogen from alcohols. The rate of hydrogen production from n-propanol was 34 μl/hr/mg dry cells. Strain No. 7 showed multiplication by budding and the best growth on n-propanol among other organic compounds tested. But its growth on n-propanol was poor under aerobic-dark conditions. NAD-linked alcohol dehydrogenase, NAD-linked aldehyde dehydrogenase, acyl-CoA synthetase and malate synthetase were found in strain No. 7. These enzymes were constitutive. On the other hand, isocitrate lyase was induced in cells grown on ethanol but not on n-propanol. No activity of phenazine methosulfate-linked alcohol dehydrogenase was detected in strain No. 7.     

Substrate Specificity of α-Glucosidase II in Rice Seed

The substrate specificity of rice α-glucosidase II was studied. The enzyme was active especially on nigerose, phenyl-α-maltoside and maltooligosaccharides. The actions on isomaltose and phenyl-α-glucoside were weak, and on sucrose and methyl-α-glucoside, negligible. The α-glucans, such as soluble starch, amylopectin, β-limit dextrin, glycogen and amylose, were also hydrolyzed.

The ratio of the maximum velocities for hydrolyses of maltose (G₂), nigerose (N), kojibiose (K), isomaltose (I), phenyl-α-maltoside (?M) and soluble starch (SS) was estimated to be 100: 94.4: 14.2: 7.1: 89.5: 103.1 in this order, and that for hydrolyses of malto-triose (G₃), -tetraose (G₄), -pentaose (G₅), -hexaose (G₆), -heptaose (G₇), -octaose (G₈), and amyloses ( and ), 113: 113: 113: 106: 113: 100: 106: 106. The Km values for N, K, I, ?M and SS were 2.4 mm, 0.58 mm, 20 mm, 1.6 mm and 5.0 mg/ml, respectively; those for G₂, G₃, G₄, G₅, G₆, G₇, G₈, and , 2.4 mm, 2.2 mm, 2.1 mm, 1.5 mm, 1.0 mm, 1.1 mm, 0.95 mm, 1.5 mm and 1.1 mm.

Rice α-glucosidase II is considered an enzyme with a preferential activity on maltooligosaccharides.