The mechanism underlying the regulation of work-related behaviors in the monomorphic ant, Myrmica kotokui

The mechanism underlying the regulation of the work performed by the members of a colony is a crucial factor in the colonial life of eusocial organisms. If the response thresholds of the workers vary, greater-than-chance variation in the prevalence of work-related behaviors (i.e., in the “working degree”) is expected, and the distribution of these behaviors should be reestablished after demographic changes. We show that greater-than-chance variation in the working degree is restored after a demographic change in the ant Myrmica kotokui. The working degree varied markedly among workers, and the degree of variation could not be explained by chance alone. Moreover, the degree of variation could not be attributed to intrinsic factors such as reproductive potential or age. After a demographic change, some previously inactive workers started to work, whereas some previously active workers became inactive. These shifts resulted in the restoration of a substantial amount of variation in the working degree. These observations all support the hypothesis that variance in the response threshold is the basis of the regulation of work-related behaviors in this ant.     

Intraannual and interannual changes in the surface area of a closed lake complex in southwestern Siberia using NOAA images

The Lake Chany complex, located in southwestern Siberia, consists of large shallow lakes with an average depth of about 2.2m. The area of the lake fluctuates with the water level, which is closely related to the amount of inflow and evaporation, as the lake complex is endorheic. Using National Oceanic and Atmospheric Administration (NOAA) satellite images of the ice-free periods from 1999 to 2004, we evaluated the seasonal changes in the lake area and surrounding vegetation of the Lake Chany complex. The maximum lake area was observed in early May and decreased until late July. The lake area in August was about 60% of the maximum. Subsequently, the area tended to increase until early October. Compared to ground-truth data, the areas undergoing seasonal fluctuations in the NOAA images corresponded to vast stands of vegetation (Phragmites australis) that were several kilometers wide. These areas seem to be influenced by the inflow of snow-melt water and reed growth. Although interannual differences in the seasonal change in lake area were not great for the whole lake complex, the isolated Yudinskii Pool showed large interannual differences during summer and autumn, suggesting that monitoring this area using NOAA images will be useful for estimating the interannual fluctuations in the southwestern Siberian environment.     

Correlation between renal distribution of leptospires during the acute phase and chronic renal dysfunction in a hamster model of infection with Leptospira interrogans

BackgroundLeptospirosis has been described as a biphasic disease consisting of hematogenous dissemination to major organs in the acute phase and asymptomatic renal colonization in the chronic phase. Several observational studies have suggested an association between leptospirosis and chronic kidney disease (CKD). We investigated the dynamics of leptospires and histopathological changes in the kidney to understand the relationship between them, and also investigated the extent of renal dysfunction in the acute and chronic phases of leptospirosis using a hamster model.FindingsHamsters (n = 68) were subcutaneously infected with 1 × 10⁴ cells of the Leptospira interrogans serovar Manilae strain UP-MMC-SM. A total of 53 infected hamsters developed fatal acute leptospirosis, and the remaining 15 hamsters recovered from the acute phase, 13 of which showed Leptospira colonization in the kidneys in the chronic phase. Five asymptomatic hamsters also had renal colonization in the chronic phase. Immunofluorescence staining showed that leptospires were locally distributed in the renal interstitium in the early acute phase and then spread continuously into the surrounding interstitium. The kidneys of the surviving hamsters in the chronic phase showed patchy lesions of atrophic tubules, a finding of chronic tubulointerstitial nephritis, which were substantially consistent with the distribution of leptospires in the renal interstitium. The degree of atrophic tubules in kidney sections correlated statistically with the serum creatinine level in the chronic phase (rs = 0.78, p = 0.01).ConclusionSubcutaneous infection with pathogenic leptospires could cause acute death or chronic leptospirosis in hamsters after surviving the acute phase. We suggest that the renal distribution of leptospires during the acute phase probably affected the extent of tubular atrophy, leading to CKD.     

Three dimensional observation of the nerve fibers along the cerebral blood vessels

Three dimensional observation of the nerve fibers along the cerebral blood vessels was investigated by scanning electron microscopy. Electron probe X-ray microanalysis was also performed in the cerebral blood vessels treated with peroxidase-antiperoxidase immunohistochemistry intensified by nickel ammonium sulfate. Nerve fibers (2-8 microns in diameter) formed a plexus on the outer surface of the adventitia. After branching, the nerve fibers penetrated the blood vessel adventitia. Substance P-immunoreactive nerve fibers showed a meshwork pattern in the outer layer of the adventitia, and vasoactive intestinal polypeptide (VIP)-immunoreactive nerve fibers revealed a spiral running pattern in the inner layer of the adventitia. Taken together with previous studies, these findings suggest that substance P nerve fibers in the cerebral arteries may not be related to arterial dilatation or constriction, but VIP nerve fibers may be vasodilative.     

An alternate method for synthesis of double-stranded DNA segments

Recent progress in the chemical synthesis of DNA has now made it possible to rapidly synthesize single-stranded DNAs over 40 bases in length. We have taken advantage of these longer DNAs in assembling and cloning a 132-base pair gene segment coding for amino acids 126 through the stop codon of human leukocyte interferon alpha 2. The method used involves DNA polymerase I-mediated repair synthesis of synthetic oligonucleotide substrates having short stretches of complementary sequence at their 3' termini. In the presence of DNA polymerase I and the four deoxyribonucleoside triphosphates, those primer-templates are converted to full length double-stranded DNAs. The economy in chemical synthesis using this approach is substantial with a greater than 40% reduction in the amount of chemical synthesis required as compared with the conventional approach. We describe in detail this methodology for the biochemical assembly of long gene segments from synthetic oligodeoxyribonucleotides.     

Biological activities of mouse haptoglobin elicited by administration of an antitumor polysaccharide,PSK

The concentration of mouse haptoglobin in serum was increased by administration of an antitumor polysaccharide, PSK. The administration of the purified mouse haptoglobin inhibited the growth of Sarcoma-180 cells implanted in ICR mice. Furthermore, this glycoprotein enhanced macrophage activitiesin vitro, as judged from the cytostatic and cytolytic activities, glycose consumption, O₂-production, and interleukin-1 production of macrophages. In addition, mouse haptoglobin enhanced the cytolytic effect of cytotoxic T-lymphocytes. These results suggested that haptoglobin has a role in restoring or enhancing the resistance of the host against tumors.Abbreviations FCS fetal calf serum - LPS lipopolysaccharide - CTL cytotoxic T-lymphocytes - IL-1 interleukin 1 Part of this work has been presented at the 14th International Congress of Chemotherapy, Kyoto, Japan, June, 1985.