The Role of Polygalacturonase (PG) in the Ripening of Apple Fruits

Polygalacturonase (PG) activity and changes in respiratory intensity of apple fruits were investigated. The respiratory rate was decreased to a preclimacteric minimum from 30 Aug. to 20 Sept., Then increased to a climacteric peak (20–30 Sept.) and again drop down gradually with approaching the senescence stage. The PG activity was undetectable in a developing fruit until the onset climacteric phase. It rose rapidly after harvest, and reaching its highest level on 27 Oct. Just a month after the climacteric peak. The PG activity fell gradually. The amount of the fractions of pectic acid in fruits changed with the modifications of PG activity. With the ripening of fruits, the content of alcohol-soluble small molecules of pectic acids was increased from 12 to 13 5 mg/100 g of tissue, while the amount of alcohol- insoluble large molecules of pectic acids reduced from 530 to 280/100 g of tissue. PG activity would indicate the destruction of cell walls and the separation of cells. The onset of softening of fruits occurred 20 days after the rise of PG activity. It is supposed that the process of softening is directly controlled by PG activity.     

ST-segment elevation associated with allergic reaction to echocardiographic contrast agent administration

We report a case of an allergic reaction after the administration of an echocardiographic contrast agent which resulted in ST-segment elevation. Hypersensitivity and allergic reactions are known causes of acute cardiovascular events. However, only limited reports are available which suggest the exact mechanism of the occurrence of angina or myocardial infarction during severe allergic reactions. In our case, through invasive imaging (coronary angiography and IVUS) we have shown for the first time a transient coronary spasm in the absence of intra-coronary thrombus and only minimal neointimal hyperplasia.     

Length variation and secondary structure of introns in the Mlc1 gene in six species of Drosophila

A nearly universal feature of intron sequences is that even closely related species exhibit a large number of insertion/deletion differences. The goal of the analysis described here is to test whether the observed pattern of insertion/deletion events in the genealogy of the myosin alkali light chain (Mlc1) gene is consistent with neutrality, and if not, to determine the underlying forces of evolutionary change. Mlc1 pre-mRNA is alternatively spliced, and one constraint is that signals necessary for tissue-specificity of directed splicing must be conserved. If the total length of an intron is functionally constrained, then the distribution of indels on branches of the gene genealogy should reflect a departure from randomness. Here we perform a phylogenetic analysis, inferring ancestral states wherever possible on a phylogeny of 29 alleles of Mlc1 from six species of Drosophila. Observed patterns of indels on the genealogy were compared to those from simulated data, with the result that we cannot reject the null hypothesis of neutrality. A clear departure from a neutral prediction was seen in the excess folding free energy predicted for the introns flanking the alternatively spliced exon. Relative rate tests also suggest a retardation in the rate of Mlc1 sequence evolution in the simulans clade.      

SUMOylation and PARylation cooperate to recruit and stabilize SLX4 at DNA damage sites

SUMOylation plays important roles in the DNA damage response. However, whether it is important for interstrand crosslink repair remains unknown. We report that the SLX4 nuclease scaffold protein is regulated by SUMOylation. We have identified three SUMO interaction motifs (SIMs) in SLX4, mutating all of which abrogated the binding of SLX4 to SUMO-2 and covalent SLX4 SUMOylation. An SLX4 mutant lacking functional SIMs is not recruited to PML nuclear bodies nor stabilized at laser-induced DNA damage sites. Additionally, we elucidated a novel role for PARylation in the recruitment of SLX4 to sites of DNA damage. Combined, our results uncover how SLX4 is regulated by post-translational modifications.     

Activating and inhibitory Fcγ receptors in rheumatoid arthritis: from treatment to targeted therapies

Fcγ receptors (FcγRs) bind the constant Fc region of IgG molecules. IgG/antigen-containing immune complexes elicit a variety of effector functions in cells that express activating FcγRs. Because activating FcγRs are present on cells from the innate immune system, such as dendritic cells, monocytes/macrophages and granulocytes, these IgG receptors form a crucial link between the innate and the acquired immune systems. Recently, the ability to detect the inhibitory FcγRIIb on cells has indicated an imbalance between activating and inhibitory FcγRs in rheumatoid arthritis. This progress offers an opportunity to study modulation of FcγR balance and could stimulate development of FcγR-directed immunotherapy.     

Outcomes of pregnancy in insulin dependent diabetic women: results of a five year population cohort study.

OBJECTIVE: To monitor pregnancies in women with pre-existent insulin dependent diabetes for pregnancy loss, congenital malformations, and fetal growth in a geographically defined area of north west England. DESIGN: Population cohort study. SETTING: 10 maternity units in Cheshire, Lancashire, and Merseyside which had no regional guidelines for the management of pregnancy in diabetic women. SUBJECTS: 462 pregnancies in 355 women with insulin dependent diabetes from the 10 centres over five years (1990-4 inclusive). MAIN OUTCOME MEASURES: Numbers and rates of miscarriages, stillbirths, and neonatal and postneonatal deaths; prevalence of congenital malformations; birth weight in relation to gestational age. RESULTS: Among 462 pregnancies, 351 (76%) resulted in a liveborn infant, 78 (17%) aborted spontaneously, nine (2%) resulted in stillbirth, and 24 (5%) were terminated. Of the terminations, nine were for congenital malformation. The stillbirth rate was 25.0/1000 total births (95% confidence interval 8.9 to 41.1) compared with a population rate of 5.0/1000, and infant mortality was 19.9/1000 live births (5.3 to 34.6) compared with 6.8/1000. The prevalence of congenital malformations was 94.0/1000 live births (63.5 to 124.5) compared with 9.7/1000 in the general population. When corrected for gestational age, mean birth weight in the sample was 1.3 standard deviations greater than that of infants of non-diabetic mothers. Infants with congenital malformations weighed less than those without. CONCLUSION: In an unselected population the infants of women with pre-existent insulin dependent diabetes mellitus have a 10-fold greater risk of a congenital malformation and a fivefold greater risk of being stillborn than infants in the general population. Further improvements in the management of pregnancy in diabetic women are needed if target of the St Vincent declaration of 1989 is to be met.     

Conservation of alternative splicing and genomic organization of the myosin alkali light-chain (Mlc1) gene among Drosophila species

The Mlc1 gene of Drosophila melanogaster encodes two MLC1 isoforms via developmentally regulated alternative pre-mRNA splicing. In larval muscle and tubular and abdominal muscles of adults, all of the six exons are included in the spliced mRNA, whereas, in the fibrillar indirect flight muscle of adult, exon 5 is excluded from the mRNA. We show that this tissue-specific pattern of alternative splicing of the Mlc1 pre-mRNA is conserved in D. simulans, D. pseudoobscura, and D. virilis. Isolation and sequencing of the Mlc1 genes from these three other Drosophila species have revealed that the overall organization of the genes is identical and that the genes have maintained a very high level of sequence identity within the coding region. Pairwise amino acid identities are 94%-99%, and there are no charge changes among the proteins. Total nucleotide divergence within the coding region of the four genes supports the accepted genealogy of these species, but the data indicate a significantly higher rate of amino acid replacement in the branch leading to D. pseudoobscura. A comparison of nucleotide substitutions in the coding portions of exon 5 and exon 6, which encode the alternative carboxyl termini of the two MLC1 isoforms, suggests that exon 5 is subject to greater evolutionary constraints than is exon 6. In addition to the coding sequences, there is significant sequence conservation within the 5' and 3' noncoding DNA and two of the introns, including one that flanks exon 5. These regions are candidates for cis- regulatory elements. Our results suggest that evolutionary constraints are acting on both the coding and noncoding sequences of the Mlc1 gene to maintain proper expression and function of the two MLC1 polypeptides.      

Behavioral budgets of captive sea otter mother–pup pairs during pup development

Instantaneous sampling of eight behavior categories for a captive mother sea otter (Enhydra lutris) and her four pups was conducted continuously during the first three months following each pup's birth. Initially, pup-grooming and rest occupied the largest proportion of the mother's time. Despite a steady decline in the amount of time the mother spent pup-grooming, the mother continued to groom the pup a substantial amount of time three months after the pup's birth. The proportion of time the mother spent resting, self-grooming, or swimming did not change significantly over the study period, suggesting that these behaviors are important to the mother's self-maintenance. The newborn pups' behaviors were initially limited to rest, active, and nursing, with large proportions of time spent resting and nursing. A significant increase in self-grooming occurred regularly by week 2, followed by increases in swimming (week 3), diving (week 6), and feeding (week 7). Three months after birth, the pups' behavior budgets were similar to their mother, with the exception that pups self-groomed substantially less than their mother self-groomed. The lower proportion of pup self-grooming may be due to the continued close proximity to their mother in captivity, which afforded extended association, and allowed the mother to continue to perform this complex behavior for the pup. © 1993 Wiley-Liss, Inc.