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The aims of this study were to observe the respiratory syncytial virus (RSV) hospitalization rate and to identify the risk factors for hospitalization for RSV infection among infants in Korea born at <35 weeks of gestational age and who had not previously received palivizumab.

Interleukin 10 (IL-10) and IL-11 are known to have anti-inflammatory activities, and they have been implicated in the pathogenesis of respiratory syncytial virus (RSV) infection.

The active site and substrate-binding mode of MD-ACO1 (Malus domestica Borkh. 1-aminocyclopropane-1-carboxylate oxidase) have been determined using site-directed mutagenesis and comparative modelling methods. The MD-ACO1 protein folds into a compact jelly-roll motif comprised of eight α-helices, 12 β-strands and several long loops. The active site is well defined as a wide cleft near the C-terminus. The co-substrate ascorbate is located in cofactor Fe2+-binding pocket, the so-called ‘2-His-1-carboxylate facial triad’. In addition, our results reveal that Arg244 and Ser246 are involved in generating the reaction product during enzyme catalysis. The structure agrees well with the biochemical and site-directed mutagenesis results. The three-dimensional structure together with the steady-state kinetics of both the wild-type and mutant MD-ACO1 proteins reveal how the substrate specificity of MD-ACO1 is involved in the catalytic mechanism, providing insights into understanding the fruit ripening process at atomic resolution.

By screening a cDNA library of auxin-treated mung bean (Vigna radiataL.) hypocotyls, we have isolated two full-length cDNA clones, pVR-ACS6 and pVR-ACS7, for 1-aminocyclopropane-1-carboxylate (ACQ synthase, the rate-limiting enzyme in the ethylene biosynthetic pathway. While pVR-ACS6 corresponds to the previously identified PCR fragment pMBAl, pVR-ACS7 is a new cDNA clone. pVR-ACS6 is 1867bp long encoding 472 amino acids (Mr = 53.6 kDa), and pVR-ACS7 is a 1840 bp clone encoding 468 amino acids (Mr = 53.1 kDa). The coding regions of pVR-ACS6 and pVR-ACS7 share 81 and 88 % identity at nucleotide and amino acid levels, respectively. Genomic Southern blot analyses suggest the existence of only one copy of ACS6and ACS7genes in the mung bean genome. Previously, it was reported that mung bean ACC synthase cDNA clone (pAIM-1) representing ACS1gene was expressed following auxin treatment. Northern blot analyses were carried out to compare the magnitudes and induction kinetics of the expression of the three genes, ACS1, ACS6and ACS7whose expressions are induced by auxin (100 µM IAA) in hypocotyls. Although all three genes are expressed in response to auxin treatment, the level of ACS1transcript is lower than those of ACS6and ACS7transcripts during the entire period of auxin treatment. ACS6and ACS7are specifically induced by auxin, while ACS1is induced by cycloheximide, and to lesser extent by excision and auxin treatment. A comparison of deduced amino acid sequences among auxin-induced ACC synthases reveals that these enzymes share a high degree of homology (65–75 %) to VR-ACS6 and VR-ACS7 polypeptides, but only about 50% to VR-ACS1 polypeptide. These results indicate that ACC synthase is encoded by a multigene family and expression of these genes is differentially regulated by auxin in mung bean hypocotyl tissue.

By screening a mung bean (Vigna radiata L.) hypocotyl cDNA library using a combination of apple (pAE12) and tomato (pTOM13) 1-aminocyclopropane1-carboxylate (ACC)-oxidase cDNAs as probes, putative ACC-oxidase clones were isolated. Based on restriction-enzyme map and DNA-sequencing analyses, they can be divided into two homology classes, represented by pVR-ACO1 and pVR-ACO2. While pVR-ACO1 and pVR-ACO2 exhibit close homology in their coding regions, their 3'-noncoding regions are divergent. pVR-ACO1 is a 1312-bp full-length clone and contains a single open reading frame encoding 317 amino acids (MW = 35.8 kDa), while pVR-ACO2 is 1172 bp long and is a partial cDNA clone encoding 308 amino acids. These two deduced amino-acid sequences share 83% identity, and display considerable sequence conservation (73–86%) to other ACC oxidases from various plant species. Northern blot analyses of RNAs isolated from hypocotyl, leaf, and stem tissues using gene-specific probes indicate that the pVR-ACO1 transcript is present in all parts of the seedling and that the expression in hypocotyls is further increased following excision. The maximum induction of ACC-oxidase transcripts occurred at about 6 h after excision, while the maximum enzyme activity was observed at 24 h. When excised hypocotyls were treated with ethylene a further enhanced level of transcripts was observed. Aminooxyacetic acid, an inhibitor of ACC-synthase activity, and 2,5-norbornadiene, an inhibitor of ethylene action, suppressed the wound-induced accumulation of ACC-oxidase mRNA, while an addition of ethylene in these tissues restored the accumulation of ACC-oxidase mRNA. These results indicate that the wound-induced expression of ACC-oxidase transcripts is mediated through wound-induced ethylene. Furthermore, when intact mung-bean seedlings were treated with exogenous ethylene, a marked increase in the level of ACC-oxidase mRNA was observed. Together, these results indicate that ethylene plays a key role in activating the expression of the ACC-oxidase gene in both intact and excised mung-bean hypocotyls.

1-Aminocyclopropane-1-carboxylate (ACC) synthase (EC 4.4.1.14) purified from apple (Malus sylvestris Mill.) fruit was subjected to trypsin digestion. Following separation by reversed-phase high-pressure liquid chromatography, ten tryptic peptides were sequenced. Based on the sequences of three tryptic peptides, three sets of mixed oligonucleotide probes were synthesized and used to screen a plasmid cDNA library prepared from poly(A)+ RNA of ripe apple fruit. A 1.5-kb (kilobase) cDNA clone which hybridized to all three probes were isolated. The clone contained an open reading frame of 1214 base pairs (bp) encoding a sequence of 404 amino acids. While the polyadenine tail at the 3'-end was intact, it lacked a portion of sequence at the 5'-end. Using the RNA-based polymerase chain reaction, an additional sequence of 148 bp was obtained at the 5'-end. Thus, 1362 bp were sequenced and they encode 454 amino acids. The deduced amino-acid sequence contained peptide sequences corresponding to all ten tryptic fragments, confirming the identity of the cDNA clone. Comparison of the deduced amino-acid sequence between ACC synthase from apple fruit and those from tomato (Lycopersicon esculentum Mill.) and winter squash (Cucurbita maxima Duch.) fruits demonstrated the presence of seven highly conserved regions, including the previously identified region for the active site. The size of the translation product of ACC-synthase mRNA was similar to that of the mature protein on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), indicating that apple ACC-synthase undergoes only minor, if any, post-translational proteolytic processing. Analysis of ACC-synthase mRNA by in-vitro translation-immunoprecipitation, and by Northern blotting indicates that the ACC-synthase mRNA was undetectable in unripe fruit, but was accumulated massively during the ripening proccess. These data demonstrate that the expression of the ACC-synthase gene is developmentally regulated.

Developing wheat (Triticum aestivum L.) endosperm was examined using ultrathin sections prepared from tissues harvested at 5, 9, 16 and 25 d after flowering. Protein bodies were evident by 9 d and displayed a variety of membranous structures and inclusions. The Golgi apparatus was a prominent organelle at all stages, and by 9 d was associated with small electron-dense inclusions. By immunocytochemical techniques, gliadin (wheat prolamine) was localized within these vesicles and in homogeneous regions of protein bodies, but not in the lumen of the rough endoplasmic reticulum. The protein bodies appear to enlarge by fusion of smaller protein bodies resulting in larger, irregular-shaped organelles. The affinity of the Golgi-derived vesicles for gliadin-specific probes during the period of maximal storage-protein synthesis and deposition indicates that this organelle includes the bulk, if not all, of the gliadin produced. The involvement of the Golgi apparatus in the packaging of gliadins into protein bodies indicates a pathway which differs from the mode of prolamine deposition in other cereals such as maize, rice and sorghum, and resembles the mechanism employed for the storage of rice glutelin and legume globulins.

Ethylene induced an increase in the level of 1‐aminocyclopropane‐1‐carboxylate (ACC) oxidase mRNA but suppressed the expression of ACC synthase transcript in mung bean hypocotyls. Induction of ACC oxidase transcript by ethylene was saturated at a low concentration (1–3 µl l−1) and detectable within 1 h after ethylene treatment; 2,5‐norbornadiene, an inhibitor of ethylene action, significantly reduced the basal level of ACC oxidase transcript present in intact mung bean hypocotyls. Treatment with the protein synthesis inhibitor cycloheximide completely inhibited the ethylene‐induced accumulation of ACC oxidase transcript, indicating that de novoprotein synthesis is necessary for expression of the ethylene‐inducible ACC oxidase gene. ABA decreased the ethylene‐induced accumulation of ACC oxidase mRNA, but restored the ethylene‐suppressed level of ACC synthase (VR‐ACS1) transcript. The protein kinase inhibitor staurosporine effectively prevented ethylene‐induced ACC oxidase gene expression, whereas it substantially recovered the ethylene‐suppressed transcript level of ACC synthase, suggesting that protein phosphorylation plays a role in the induction of ACC oxidase and the suppression of ACC synthase by ethylene in mung bean hypocotyls. Okadaic acid, a potent inhibitor of protein phosphatase, did not affect the expression of ACC oxidase. However, addition of okadaic acid along with ethylene effectively blocked the ethylene‐induced accumulation of ACC oxidase transcript, while there was an increase in the level of ethylene‐suppressed ACC synthase transcript. These results indicate that protein dephosphorylation in addition to phosphorylation is necessary for the ethylene signaling that regulates the expression of these genes.

Telomeres are protective nucleoprotein structures at the ends of linear eukaryotic chromosomes. In contrast to double-stranded-specific telomere-binding proteins, the cellular roles of single-stranded-specific telomeric proteins are not well understood in higher plants. Three highly conserved tobacco G-strand-specific telomere-binding protein paralogs (NtGTBP1, NtGTBP2, and NtGTBP3) were identified and characterized. All three NtGTBPs were able to bind specifically to the plant single-stranded telomeric repeat elements in vitro with similar affinities. Suppression of NtGTBP1by means of the RNAi-mediated gene knock-down method resulted in developmental defects in transgenic tobacco plants accompanied by lengthened telomeres, extra-chromosomal telomeric circles, and abnormal anaphase bridges. These results suggest that the down-regulation of NtGTBP1results in genome instability. NtGTBP1 prevented in vitro strand invasion, a prerequisite process for inter-chromosomal telomeric recombination. Therefore, tobacco NtGTBP1 is one of the essential factors for telomere stability. Because abnormal telomeric elongation and recombination due to the suppression of NtGTBP1are reminiscent of the recombinational telomere lengthening mechanism that purportedly operates in telomerase negative cancer cells, it is of interest to investigate whether telomeric recombination is associated with cell death in animal systems.

A recombinant cDNA clone encoding a major rice seed storage prolamine was isolated by antibody screening of a cDNA λgt 11 library. This clone contained a single open reading frame encoding a putative rice prolamine precursor ( Mr17 300). In contrast to other cereal prolamines, the primary sequence of the rice prolamine was devoid of any major tandem repetitive sequences, a feature prevalent in all cereal prolamines studied to date. No significant homology was detected between the rice prolamine and other cereal prolamines, indicating that the rice gene evolved from unique ancestral DNA segments.

Rice seeds accumulate both glutelins and prolamines as storage proteins with the former polypeptides being the predominant reserve. To evaluate the expression of the genes that encode for these proteins during seed development, the transcription activities and mRNA levels of several gene classes that comprise these multigene families were assessed. Results from nuclear run-on transcription assays and RNA blot studies showed that the expression of these gene classes for each multigene family was not coordinate but instead differentially regulated at both the transcriptional and post-transcriptional levels. Quantification of their total mRNA levels revealed equimolar amounts of their mRNAs in 5 and 10 day old seeds and a 40% excess of prolamine transcripts, relative to glutelin transcripts, in seeds of 15 days and older. In spite of the significant steady state levels of prolamine transcripts, glutelin mRNAs were detected at two-fold greater excess in membrane bound polysomes throughout seed development, thereby accounting for, at least in part, the greater accumulation of this storage protein in rice endosperm. These results suggest that, in addition to regulation at the transcriptional/post-transcriptional levels, ER membrane-associated translational control is also involved in the expression of rice seed storage protein multigene families.

Telomeres are specialized nucleoprotein complexes that function to protect eukaryotic chromosomes from recombination and erosion. Several telomere binding proteins (TBPs) have been characterized in higher plants, but their detailed in vivo functions at the plant level are largely unknown. In this study, we identified and characterized OsTRFL1 (Oryza sativa Telomere Repeat-binding Factor Like 1) in rice, a monocot model crop. Although OsTRFL1 did not directly bind to telomere repeats (TTTAGGG)4 in vitro, it was associated with telomeric sequences in planta. OsTRFL1 interacted with rice TBPs, such as OsTRBF1 and RTBP1, in yeast and plant cells as well as in vitro. Thus, it seems likely that the association of OsTRFL1 with other TBPs enables OsTRFL1 to bind to telomeres indirectly. T-DNA inserted OsTRFL1 knock-out mutant rice plants displayed significantly longer telomeres (6-25 kb) than those (5-12 kb) in wild-type plants, indicating that OsTRFL1 is a negative factor for telomere lengthening. The reduced levels of OsTRFL1 caused serious developmental defects in both vegetative and reproductive organs of rice plants. These results suggest that OsTRFL1 is an essential factor for the proper maintenance of telomeres and normal development of rice. [BMB Reports 2018; 51(11): 578-583].