Role for mitogen-activated protein kinase p38 alpha in lung epithelial branching morphogenesis

In the early stages of lung development, the endoderm undergoes extensive and stereotypic branching morphogenesis. During this process, a simple epithelial bud develops into a complex tree-like system of tubes specialized for the transport and exchange of gas with blood. The endodermal cells in the distal tips of the developing lung express a special set of genes, have a higher proliferation rate than proximal part, undergo shape change and initiate branching morphogenesis. In this study, we found that of the four p38 genes, only p38α mRNA is localized specifically to the distal endoderm suggesting a role in the regulation of budding morphogenesis. Chemical inhibitors specific for the p38α and p38β isoforms suppress budding of embryonic mouse lung explants and isolated endoderm in vitro. Specific knockdown of p38α in cultured lung endoderm using shRNA also inhibited budding morphogenesis, consistent with the chemical inhibition of the p38 signaling pathway. Disruption of p38α did not affect proliferation or expression of the distal cell markers, Sox9 and Erm. However, the amount of E-cadherin protein increased significantly and ectopic expression of E-cadherin also impaired budding of endoderm in vitro. These results suggest that p38α modulates epithelial cell-cell interactions and possibly cell rearrangement during branching morphogenesis. This study provides the first evidence that p38α is involved in the morphogenesis of an epithelial organ.     

Analyses of functional interaction between RECQL1, RECQL5, and BLM which physically interact with DNA topoisomerase IIIalpha

RECQL1 and RECQL5 as well as BLM reportedly interact with TOP3alpha whose defect is lethal for the cell. Therefore in this study, we characterized recql5/recql1/blm triple mutants from DT40 cells to determine whether the triple mutants show a top3alpha disrupted cell-like phenotype. The triple mutants are viable. Moreover, both blm/recql1 and recql5/blm cells, and recql5/recql1/blm cells grew slightly slower than blm cells, that is, triple mutant cells grew almost the same rate as either of the double mutant cells. The blm cells showed sensitivity to methyl methanesulfonate (MMS) and ultraviolet light (UV), about a 10-fold increase in sister chromatid exchange (SCE), and about a 3-fold increase in damage-induced mitotic chiasma compared to wild-type cells. The triple mutants showed the same sensitivity to MMS or UV and the same frequency of damage-induced mitotic chiasma compared to those of blm cells, indicating that unlike BLM, RECQL1 and RECQL5 play a little role in the repair of or tolerance to DNA damages. However, recql5/blm cells showed higher frequency of SCE than blm cells, whereas the RECQL1 gene disruption had no effect on SCE in blm cells and even in recql5/blm cells.     

Why have endemic pollinators declined on the Ogasawara Islands?

Flower visitors recently decreased in the Ogasawara Islands which are subtropical Pacific oceanic islands located 1,000 km south from Japan mainland. The aim of this study was to determine the main cause of this pollinator decline. We assumed four hypothesis, (i) honeybee competition hypothesis, (ii) forest decline hypothesis, (iii) agricultural insecticides hypothesis, and (iv) anole predation hypothesis. They were tested by distribution survey in the field, historical survey using literature, and predation experiment using mesh cages. As a result, the factors affecting the distribution among the islands and the timing of observed declines of native pollinators supported the anole predation hypothesis rather than other hypotheses. In addition, result of experimental predation test well explained the composition of flower visitors in the main islands (Chichi-jima and Haha-jima). So, we concluded that one invasive predator (the anole) has changed the pollination network in the Ogasawara Islands. To conserve the native pollination network, eradication of this invasive predator should take priority over the eradication of honeybees.     

Molecular cloning, expression, and characterization of a novel endo-alpha-N-acetylgalactosaminidase from Enterococcus faecalis

We report here the molecular cloning, expression and characterization of a novel endo-alpha-N-acetylgalactosaminidase, classified into the GH101 family, from Enterococcus faecalis (endo-EF). The recombinant endo-EF was found to catalyze the liberation of core1-disaccharides (Galbeta1-3GalNAc) from core1-pNP (Galbeta1-3GalNAcalpha-pNP) like other GH101 family enzymes. However, endo-EF seems to differ in specificity from the GH101 enzymes reported to date, because it was able to release trisaccharides from core2-pNP (Galbeta1-3[GlcNAcbeta1-6]GalNAcalpha-pNP) and tetrasaccharides from Gal-core2-pNP (Galbeta1-3[Galbeta1-3GlcNAcbeta1-6]GalNAcalpha-pNP). Interestingly, the enzyme could transfer not only core1-disaccharides but also core2-trisaccharides to alkanols generating alkyl-oligosaccharides. Endo-EF should facilitate O-glycoprotein research.     

Abnormal uterus with polycysts, accumulation of uterine prostaglandins, and reduced fertility in mice heterozygous for acyl-CoA synthetase 4 deficiency.

Arachidonate released by various stimuli is rapidly reesterified into membrane phospholipids initiated by acyl-CoA synthetase (ACS) and subsequent acyl-transfer reactions. ACS4 is an arachidonate-preferring enzyme abundant in steroidogenic tissues and postulated to modulate eicosanoid production. Female mice heterozygous for ACS4 deficiency become pregnant less frequently and produce small litters with extremely low transmission of the disrupted alleles. Striking morphological changes, including extremely enlarged uteri and lumina filled with numerous proliferative cysts of various sizes, were detected in ACS4+/- females. Furthermore, marked accumulation of prostaglandins was seen in the uterus of the heterozygous females. These results indicate that ACS4 modulates female fertility and uterine prostaglandin production.     

Germination strategy of Striga hermonthica involves regulation of ethylene biosynthesis

Ethylene involvement in germination of Striga hermonthica (Del.) Benth., an important root parasitic weed on poaceous crops, was investigated at the physiological and molecular levels. Seeds, conditioned at 30°C for 14 days, were treated with ethylene, ethephon or 1-aminocyclopropane-1-carboxylic acid (ACC). Ethylene consistently induced low germination. Ethephon and ACC effectively stimulated germination at concentrations of 0.01 and 1 m M , respectively. In contrast to ethylene, both ethephon and ACC acted in a concentration-dependent manner. Germination induced by the synthetic strigolactone GR24 was inhibited by aminoethoxyvinylglycine (AVG) and 1-methylcyclopropene. ACC reversed the inhibition caused by AVG. When seeds were treated with GR24 in sealed vials, ethylene concentration in headspace gas increased prior to the onset of germination. Total RNA extracted from germinating seeds 12 h after GR24 treatment was used for PCR-based amplification of cDNA fragments encoding the ACC synthase- and oxidase-active site domains. Two distinct cDNA fragments encoding ACC synthase ( SHACS1 and SHACS2 ) and one encoding ACC oxidase ( SHACO1 ) were cloned and sequenced. Southern analysis suggested that each of the cloned genes was present as a single copy in the genome of S. hermonthica . Northern analyses showed that SHACS1 exhibited a temporal change in expression peaking at 10 h after GR24 treatment, which coincided with a steady increase in ethylene concentration. SHACS2 was expressed at a low level with a similar trend. SHACO1 exhibited a temporal change in expression peaking at 15 days during conditioning, when seed response to GR24 was maximal. In summary, expression of ACC synthase and ACC oxidase genes was found to be responsive to a germination stimulant and to conditioning, respectively. The implications of these findings with respect to germination of S. hermonthica under field conditions are discussed.     

Prediction of MHC Class I Binding Peptides by a Query Learning Algorithm Based on Hidden Markov Models

A query learning algorithm based on hidden Markov models (HMMs) isdeveloped to design experiments for string analysis and prediction of MHCclass I binding peptides. Query learning is introduced to aim at reducingthe number of peptide binding data for training of HMMs. A multiple numberof HMMs, which will collectively serve as a committee, are trained withbinding data and used for prediction in real-number values. The universeof peptides is randomly sampled and subjected to judgement by the HMMs.Peptides whose prediction is least consistent among committee HMMs aretested by experiment. By iterating the feedback cycle of computationalanalysis and experiment the most wanted information is effectivelyextracted. After 7 rounds of active learning with 181 peptides in all,predictive performance of the algorithm surpassed the so far bestperforming matrix based prediction. Moreover, by combining the bothmethods binder peptides (log Kd < -6) could be predicted with84% accuracy. Parameter distribution of the HMMs that can be inspectedvisually after training further offers a glimpse of dynamic specificity ofthe MHC molecules.     

Caste-specific N and C isotope ratios in fungus-growing termites with special reference to uric acid preservation and their nutritional interpretation

Abstract 1. Nitrogen and carbon isotope ratios and uric acid concentrations in fungus-growing termites (Isoptera: Termitidae: Macrotermitinae), sampled in Cameroon and Thailand, were determined in order to compare castes that are known to differ in behaviour and feeding habits.
2. Nitrogen isotope ratios (δ¹⁵N) were either not significantly changed or lower in workers compared with the diet (the fungus combs), whereas carbon isotope ratios (δ¹³C) were higher in worker termites than in the fungus combs.
3. In old workers, δ¹⁵N values were unexpectedly low and correlated negatively with whole-body uric acid concentrations. This indicates that older workers retain uric acid, which has a low δ¹⁵N value, to conserve nitrogen within the colony and, furthermore, that older colony members may ultimately be consumed by younger conspecifics.     

Detection of Corynebacterium kutscheri from the oral cavity of rats.

A simple and useful method for the detection of C. kutscheri from the oral cavity of living rats was devised. In 10 sacrificed rats from two naturally and subclinically infected conventional colonies, 10(4.28) or 10(3.84) CFU/ml C. kutscheri were isolated from upper incisor swab extractions, while 10(1.38) or 10(1.58) and < 10 or 10(1.56) CFU/ml from the upper soft palate and pharynx, respectively. In another survey with 26 living animals, which were reared on the same rack, organisms were detected from the upper incisor and gingival swabs in 15 of 26 rats (57.7%). The results were reproducible at a second survey 10 days later. No organisms were isolated from any sites of the orally negative rats. These results indicated that culture of swab specimens from the upper incisors and gingivae of incisors is useful for the detection of C. kutscheri infection in living rats.     

Complete genome sequences of Krokinobacter sp. strain 4H-3-7-5 and Lacinutrix sp. strain 5H-3-7-4, polysaccharide-degrading members of the family Flavobacteriaceae

Two members of the family Flavobacteriaceae were isolated from subseafloor sediments using artificial seawater with cellulose, xylan, and chitin as the sole carbon and energy sources. Here, we present the complete genome sequences of Krokinobacter sp. strain 4H-3-7-5 and Lacinutrix sp. strain 5H-3-7-4, which both encode putatively novel enzymes involved in cellulose, hemicellulose, and chitin metabolism.