Salinity thresholds for understory plants in coastal wetlands

The effects of sea level rise and coastal saltwater intrusion on wetland plants can extend well above the high-tide line due to drought, hurricanes, and groundwater intrusion. Research has examined how coastal salt marsh plant communities respond to increased flooding and salinity, but more inland coastal systems have received less attention. The aim of this study was to identify whether ground layer plants exhibit threshold responses to salinity exposure. We used two vegetation surveys throughout the Albemarle-Pamlico Peninsula (APP) of North Carolina, USA to assess vegetation in a low elevation landscape (≤?3.8 m) experiencing high rates of sea level rise (3–4 mm/year). We examined the primary drivers of community composition change using Non-metric Multidimensional Scaling (NMDS) and used Threshold Indicator Taxa Analysis (TITAN) to detect thresholds of compositional change based on indicator taxa, in response to potential indicators of exposure to saltwater (Na, and the Σ Ca?+?Mg) and elevation. Salinity and elevation explained 64% of the variation in community composition, and we found two salinity thresholds for both soil Na⁺ (265 and 3843 g Na⁺/g) and Ca⁺ +?Mg⁺ (42 and 126 µeq/g) where major changes in community composition occur on the APP. Similar sets of species showed sensitivity to these different metrics of salt exposure. Overall, our results showed that ground layer plants can be used as reliable indicators of salinity thresholds in coastal wetlands. These results can be used for monitoring salt exposure of ecosystems and for identifying areas at risk for undergoing future community shifts.

     

Effects of phospholemman downregulation on contractility and [Ca(2+)]i transients in adult rat cardiac myocytes

Phospholemman (PLM) expression was increased in rat hearts after myocardial infarction (MI). Overexpression of PLM in normal adult rat cardiac myocytes altered contractile function and cytosolic Ca(2+) concentration ([Ca(2+)](i)) homeostasis in a manner similar to that observed in post-MI myocytes. In this study, we tested whether PLM downregulation in normal adult rat myocytes resulted in contractility and [Ca(2+)](i) transient changes opposite to those observed in post-MI myocytes. Compared with control myocytes infected with adenovirus (Adv) expressing green fluorescent protein (GFP) alone, myocytes infected with Adv expressing both GFP and rat antisense PLM (rASPLM) had 23% less PLM protein (P < 0.012) at 3 days, but no differences were found in sarcoplasmic reticulum (SR) Ca(2+)-ATPase, Na(+)/Ca(2+) exchanger (NCX1), Na(+)-K(+)-ATPase, and calsequestrin levels. SR Ca(2+) uptake and whole cell capacitance were not affected by rASPLM treatment. Relaxation from caffeine-induced contracture was faster, and NCX1 current amplitudes were higher in rASPLM myocytes, indicating that PLM downregulation enhanced NCX1 activity. In native rat cardiac myocytes, coimmunoprecipitation experiments indicated an association of PLM with NCX1. At 0.6 mM [Ca(2+)](o), rASPLM myocytes had significantly (P < 0.003) lower contraction and [Ca(2+)](i) transient amplitudes than control GFP myocytes. At 5 mM [Ca(2+)](o), both contraction and [Ca(2+)](i) transient amplitudes were higher in rASPLM myocytes. This pattern of contractile and [Ca(2+)](i) transient behavior in rASPLM myocytes was opposite to that observed in post-MI rat myocytes. We conclude that downregulation of PLM in normal rat cardiac myocytes enhanced NCX1 function and affected [Ca(2+)](i) transient and contraction amplitudes. We suggest that PLM downregulation offers a potential therapeutic strategy for ameliorating contractile abnormalities in MI myocytes.     

Northern bobwhite breeding season habitat selection in fire-maintained pine woodland

Despite the acknowledged importance of prescribed fire in creating northern bobwhite (Colinus virginianus) breeding cover, little research has investigated bobwhite breeding season habitat selection relative to time since fire. In 2016 and 2017, we monitored radio-tagged bobwhite on a 17,000-ha portion of a military installation managed with frequent (every ~3 years) prescribed fires, applied during the growing and dormant seasons. We monitored bobwhite to determine which vegetation characteristics associated with prescribed burning were important to bobwhite breeding season habitat selection at the microsite (i.e., telemetry location compared to nearby random location) and the macrosite scale (i.e., the burn-unit containing the location compared to study area availability). During 2 breeding seasons, we collected 2,315 bobwhite locations and compared percent cover of vegetation, days since burn, basal area, and distance to key landscape features (e.g., stream, wildlife opening) at a subset of microsite locations (301 locations during 2016 and 890 locations during 2017) to paired random locations. At the microsite scale, bobwhite selected lower basal area of hardwoods, greater woody understory cover, greater other (not wiregrass [Aristida stricta]) grass cover, and greater forb cover than at random points. At the macrosite scale, bobwhite selected units with <4.6 m²/ha basal area (combined hardwoods and pines) in 2016 and units with <9.2 m²/ha basal area in 2017. At the macrosite scale, bobwhite selected for areas burned in the dormant season of the same year, avoided areas burned in the growing season of the same year, and used other times since last burn categories proportionate to their availability. The selection for a low basal area at both scales indicates prescribed fire effects would be limited by shading from dense overstory, and the shrubs, grasses, and forbs that provide essential cover for bobwhite during the breeding season will not develop. In lower productivity soil regions similar to our study area, we advise that thinning operations set target basal areas below 10 m²/ha to create and maintain breeding season habitat for northern bobwhite. © 2019 The Wildlife Society     

Dynamic and Thermodynamic Response of the Ras Protein Cdc42Hs upon Association with the Effector Domain of PAK3

Human cell division cycle protein 42 (Cdc42Hs) is a small, Rho-type guanosine triphosphatase involved in multiple cellular processes through its interactions with downstream effectors. The binding domain of one such effector, the actin cytoskeleton-regulating p21-activated kinase 3, is known as PBD46. Nitrogen-15 backbone and carbon-13 methyl NMR relaxation was measured to investigate the dynamical changes in activated GMPPCP·Cdc42Hs upon PBD46 binding. Changes in internal motion of the Cdc42Hs, as revealed by methyl axis order parameters, were observed not only near the Cdc42Hs–PBD46 interface but also in remote sites on the Cdc42Hs molecule. The binding-induced changes in side-chain dynamics propagate along the long axis of Cdc42Hs away from the site of PBD46 binding with sharp distance dependence. Overall, the binding of the PBD46 effector domain on the dynamics of methyl-bearing side chains of Cdc42Hs results in a modest rigidification, which is estimated to correspond to an unfavorable change in conformational entropy of approximately − 10 kcal mol^− 1 at 298 K. A cluster of methyl probes closest to the nucleotide-binding pocket of Cdc42Hs becomes more rigid upon binding of PBD46 and is proposed to slow the catalytic hydrolysis of the γ phosphate moiety. An additional cluster of methyl probes surrounding the guanine ring becomes more flexible on binding of PBD46, presumably facilitating nucleotide exchange mediated by a guanosine exchange factor. In addition, the Rho insert helix, which is located at a site remote from the PBD46 binding interface, shows a significant dynamic response to PBD46 binding.     

A histological and immunohistochemical study of the effects of N-acetyl cysteine on retinopathy of prematurity by modifying insulin-like growth factor-1

Retinopathy of prematurity (ROP) is a vasoproliferative disorder that occurs in premature infants and may lead to permanent visual impairment. We investigated both the possible protective role of N-acetyl cysteine (NAC) for preventing ROP and the role of IGF-1 in the disorder. Forty-five newborn rats were divided into three groups. Group 1 was raised in room air as controls. Group 2 was exposed to 60% oxygen for 14 days after birth, then transferred to room air. Group 3 was exposed to the same conditions as group 2, but received intraperitoneal injections of NAC on postnatal days 7–17. After 35 days, both eyes of all rats were processed for histology. Some sections were stained with hematoxylin and eosin to assess structural changes and other sections were immunostained to determine the location of IGF-1. Frozen sections also were prepared and stained for adenosine triphosphatase to detect retinal blood vessels. Compared to the controls, more blood vessels, many of which were abnormal, and increased IGF-1 expression were observed in group 2. In group 3, abnormal blood vessels and IGF-1 expression were less evident. NAC appeared to be an effective vascular-protective agent for ROP by decreasing IGF-1 expression.     

Phylogenetic relationships and taxonomic position of Chlorella -like isolates from low pH environments (pH < 3.0)

Background  

Little is known about phytoplankton communities inhabiting low pH environments such as volcanic and geothermal sites or acidic waters. Only specialised organisms are able to tolerate such extreme conditions. There is, thus, low species diversity. We have characterised the previously isolated acid tolerant Chlorella -like microalgae Viridiella fridericiana and Chlorella protothecoides var. acidicola by microscopical and biomolecular methods in order to assess their phylogenetic relationships.     

Heterogeneous distribution of glutamine synthetase during rat liver development

Two days before birth, immunohistochemical detection of glutamine synthetase already reveals a heterogeneous distribution pattern related to the vascular architecture of the liver. Only a small number of hepatocytes in the vicinity of the efferent venules show relatively high staining intensity. Before that age, only megakaryocytes show intense staining, while liver parenchyma is only faintly stained. The developmental profile of glutamine synthetase activity shows two periods of increasing enzyme activity: one in the perinatal period and one in the second and third postnatal week. Both periods are correlated with high levels of circulating corticosteroid hormones. Although the relative number of intensely stained hepatocytes increases during the first rise in enzyme activity, the second rise is correlated with a decreasing number of glutamine synthetase-positive hepatocytes which, however, show a considerable increase in staining intensity. Carbamoylphosphate synthetase shows a homogeneous distribution pattern in the perinatal period. Conditions that lead during development to a relatively high level of glutamine synthetase expression in the pericentral compartment apparently originate before the appearance of conditions that lead to a relatively high level of carbamoylphosphate synthetase gene expression in the periportal compartment. Our results indicate that downstream localization of glutamine synthetase in liver acinus is essential from the perinatal period onwards, whereas reciprocal distribution of glutamine synthetase and carbamoylphosphate synthetase gene expression (that is found in adult rat liver) is not.     

Inactivation of the Sema5a gene results in embryonic lethality and defective remodeling of the cranial vascular system

The semaphorins are a large family of proteins involved in the patterning of both the vascular and the nervous systems. In order to analyze the function of the membrane-bound semaphorin 5A (Sema5A), we generated mice homozygous for a null mutation in the Sema5a gene. Homozygous null mutants die between embryonic development days 11.5 (E11.5) and E12.5, indicating an essential role of Sema5A during embryonic development. Mutant embryos did not show any morphological defects that could account for the lethality of the mutation. A detailed analysis of the vascular system uncovered a role of Sema5A in the remodeling of the cranial blood vessels. In Sema5A null mutants, the complexity of the hierarchically organized branches of the cranial cardinal veins was decreased. Our results represent the first genetic analysis of the function of a class 5 semaphorin during embryonic development and identify a role of Sema5A in the regional patterning of the vasculature.     

Quantification of angiogenesis in estrogen receptor-positive and negative breast carcinoma

Background

The objective of this study was to evaluate angiogenesis according to CD34 antigen expression in estrogen receptor (ER)-positive and negative breast carcinomas.

Methods

This study comprised 64 cases of infiltrating ductal carcinoma in postmenopausal women divided into two groups: Group A: ER-positive, n = 35; and Group B: ER-negative, n = 29. The anti-CD34 monoclonal antibody was used as a marker for endothelial cells. Microvessel count was carried out in 10 fields per slide using a 40× objective lens (magnification 400×). Statistical analysis of the data was performed using Student's t-test (p < 0.05).

Results

The mean number of vessels stained with the anti-CD34 antibody in the estrogen receptor-positive and negative tumors was 23.51 ± 1.15 and 40.24 ± 0.42, respectively. The number of microvessels was significantly greater in the estrogen receptor-negative tumors (p < 0.001).

Conclusion

ER-negative tumors have significantly greater CD34 antigen expression compared to ER-positive tumors.