Further evidence for a cell surface proteinase essential to the growth of cultured fibroblasts

Specific antibodies and protein proteinase inhibitors will inhibit cell-surface proteinase activity on human fibroblasts and cause a concomitant inhibition of DNA synthesis and of cell multiplication. An insolubilized proteinase inhibitor also inhibits cell multiplication. The same reagents partially inhibit the multiplication of mouse L cells, both in monolayer and suspension culture, and inhibit the mitogenic effect of epidermal growth factor (EGF) on both types of cell.     

Comparative analysis of multiple protein-sequence alignment methods [published erratum appears in Mol Biol Evol 1994 Sep;11(5):811]

We have analyzed a total of 12 different global and local multiple protein-sequence alignment methods. The purpose of this study is to evaluate each method's ability to correctly identify the ordered series of motifs found among all members of a given protein family. Four phylogenetically distributed sets of sequences from the hemoglobin, kinase, aspartic acid protease, and ribonuclease H protein families were used to test the methods. The performance of all 12 methods was affected by (1) the number of sequences in the test sets, (2) the degree of similarity among the sequences, and (3) the number of indels required to produce a multiple alignment. Global methods generally performed better than local methods in the detection of motif patterns.      

The biophysics and biochemistry of smooth muscle contraction.

In this review the biophysics and biochemistry of smooth muscle contraction are dealt with. We describe a new model for the study of bronchial smooth muscle, which facilitates study of cellular contractile mechanisms. A new concept emerging is that study of steady-state mechanical parameters such as maximal isometric force (Po) velocity is inadequate because two types of crossbridges (normally cycling (NBR) and latch) seem to be sequentially active during smooth muscle contraction. Thus quick-release techniques are required to characterize the force-velocity properties of the two types of bridges. Pathophysiological processes that affect the muscle's shortening ability seem to affect the early NBRs only. With respect to maximal shortening capacity of the smooth muscle, the role of loading is very important. The differences between isotonic, elastic, and viscous loading are considerable. Ultimately, the time course and magnitude of loading should exactly resemble that operative in vivo. Once again, it is the characteristic of loading in the early phase of contraction that is crucial, as most of the shortening in smooth muscle occurs early in the contraction. While the maximum force developed by smooth muscle per unit cross-sectional area is the same as for striated muscle, the velocity is 50 times less. The properties of the series and parallel elastic elements of smooth muscle are described. The latter, when in compression mode, acts as an internal resistance to shortening and probably limits it. Isotonic relaxation has therefore not been studied in smooth muscle. We have developed a shortening parameter that is independent of the load on the muscle and of the initial length of the muscle's contractile element. We report the novel observation that isotonically relaxing smooth muscle reactivates itself, resulting in terminal slowing of the relaxation process. With respect to the biochemistry of smooth muscle contraction, contractile (actin isoforms, myosin heavy and light chains and their isoforms), regulatory (calmodulin-4 Ca2+, myosin light chain kinase, myosin light chain and its phosphorylation, tropomyosin, caldesmon, and calponin), and cytoskeletal (chiefly desmin and vimentin) proteins are discussed. While the kinase activates the contractile system, caldesmon and calponin modulate the activity downward. The cytoskeletal proteins desmin, vimentin, and alpha-actinin could constitute the muscle cell's internal resistor.     

Non-Essential Role for TLR2 and Its Signaling Adaptor Mal/TIRAP in Preserving Normal Lung Architecture in Mice

Myeloid differentiation factor 88 (MyD88) and MyD88-adaptor like (Mal)/Toll-interleukin 1 receptor domain containing adaptor protein (TIRAP) play a critical role in transducing signals downstream of the Toll-like receptor (TLR) family. While genetic ablation of the TLR4/MyD88 signaling axis in mice leads to pulmonary cell death and oxidative stress culminating in emphysema, the involvement of Mal, as well as TLR2 which like TLR4 also signals via MyD88 and Mal, in the pathogenesis of emphysema has not been studied. By employing an in vivo genetic approach, we reveal here that unlike the spontaneous pulmonary emphysema which developed in Tlr4^−/− mice by 6 months of age, the lungs of Tlr2^−/− mice showed no physiological or morphological signs of emphysema. A more detailed comparative analysis of the lungs from these mice confirmed that elevated oxidative protein carbonylation levels and increased numbers of alveolar cell apoptosis were only detected in Tlr4^−/− mice, along with up-regulation of NADPH oxidase 3 (Nox3) mRNA expression. With respect to Mal, the architecture of the lungs of Mal^−/− mice was normal. However, despite normal oxidative protein carbonylation levels in the lungs of emphysema-free Mal^−/− mice, these mice displayed increased levels of apoptosis comparable to those observed in emphysematous Tlr4^−/− mice. In conclusion, our data provide in vivo evidence for the non-essential role for TLR2, unlike the related TLR4, in maintaining the normal architecture of the lung. In addition, we reveal that Mal differentially facilitates the anti-apoptotic, but not oxidant suppressive, activities of TLR4 in the lung, both of which appear to be essential for TLR4 to prevent the onset of emphysema.     

Genetic Susceptible Locus in NOTCH2 Interacts with Arsenic in Drinking Water on Risk of Type 2 Diabetes

Background

Chronic exposure to arsenic in drinking water is associated with increased risk of type 2 diabetes mellitus (T2DM) but the underlying molecular mechanism remains unclear.

Objectives

This study evaluated the interaction between single nucleotide polymorphisms (SNPs) in genes associated with diabetes and arsenic exposure in drinking water on the risk of developing T2DM.

Methods

In 2009–2011, we conducted a follow up study of 957 Bangladeshi adults who participated in a case-control study of arsenic-induced skin lesions in 2001–2003. Logistic regression models were used to evaluate the association between 38 SNPs in 18 genes and risk of T2DM measured at follow up. T2DM was defined as having a blood hemoglobin A1C level greater than or equal to 6.5% at follow-up. Arsenic exposure was characterized by drinking water samples collected from participants'' tubewells. False discovery rates were applied in the analysis to control for multiple comparisons.

Results

Median arsenic levels in 2001–2003 were higher among diabetic participants compared with non-diabetic ones (71.6 µg/L vs. 12.5 µg/L, p-value <0.001). Three SNPs in ADAMTS9 were nominally associated with increased risk of T2DM (rs17070905, Odds Ratio (OR)  = 2.30, 95% confidence interval (CI) 1.17–4.50; rs17070967, OR = 2.02, 95%CI 1.00–4.06; rs6766801, OR = 2.33, 95%CI 1.18–4.60), but these associations did not reach the statistical significance after adjusting for multiple comparisons. A significant interaction between arsenic and NOTCH2 (rs699780) was observed which significantly increased the risk of T2DM (p for interaction = 0.003; q-value = 0.021). Further restricted analysis among participants exposed to water arsenic of less than 148 µg/L showed consistent results for interaction between the NOTCH2 variant and arsenic exposure on T2DM (p for interaction  = 0.048; q-value = 0.004).

Conclusions

These findings suggest that genetic variation in NOTCH2 increased susceptibility to T2DM among people exposed to inorganic arsenic. Additionally, genetic variants in ADAMTS9 may increase the risk of T2DM.     

Bucking the trend: the African Black Oystercatcher as a recent conservation success story

The African Black Oystercatcher Haematopus moquini is a charismatic, southern African near-endemic, wader species, that is often seen as a flagship species for coastal bird conservation, as it was recently down-listed regionally to Least Concern on the IUCN Red List of Threatened Species. To celebrate this rare conservation success story, BirdLife South Africa named it the 2018 Bird of the Year and ran a year-long programme in collaboration with the Nature’s Valley Trust highlighting aspects of the species’ biology, current threats, and conservation success. We used data collected by the Southern African Bird Atlas Project (SABAP1 and SABAP2) to examine changes in the species’ range and relative abundance, both in the records between the two projects, as well as trends within the SABAP2 sampling period (2008–2017). This case study enabled us to assess whether such metrics can accurately reflect abundance and distributional changes in a species. We found increases in the reported range and the reporting rates between the two Atlas projects, and that the SABAP2 reporting rate was stable. Regionally, across four coastal categories, the reporting rate was lowest in KwaZulu-Natal, though this region also showed an increase in the probability of reporting during the SABAP2 period. While corroborating the recent change in the species’ conservation status, we also provide good evidence that the long-term SABAP data can be used successfully to assess population trends and range changes over time.     

Structure-function correlation in airway smooth muscle adapted to different lengths

Airway smooth muscle is able to adapt and maintain a nearly constant maximal force generation over a large length range. This implies that a fixed filament lattice such as that found in striated muscle may not exist in this tissue and that plastic remodeling of its contractile and cytoskeletal filaments may be involved in the process of length adaptation that optimizes contractile filament overlap. Here, we show that isometric force produced by airway smooth muscle is independent of muscle length over a twofold length change; cell cross-sectional area was inversely proportional to cell length, implying that the cell volume was conserved at different lengths; shortening velocity and myosin filament density varied similarly to length change: increased by 69.4% ± 5.7 (SE) and 76.0% ± 9.8, respectively, for a 100% increase in cell length. Muscle power output, ATPase rate, and myosin filament density also have the same dependence on muscle cell length: increased by 35.4% ± 6.7, 34.6% ± 3.4, and 35.6% ± 10.6, respectively, for a 50% increase in cell length. The data can be explained by a model in which additional contractile units containing myosin filaments are formed and placed in series with existing contractile units when the muscle is adapted at a longer length. muscle contraction; myosin filaments; ATPase activity; electron microscopy