The expression of the rice (Oryza sativa L.) homologue of Snm1 is induced by DNA damages

We isolated and characterized the rice homologue of the DNA repair gene Snm1 (OsSnm1). The length of the cDNA was 1862bp; the open reading frame encoded a predicted product of 485 amino acid residues with a molecular mass of 53.2kDa. The OsSnm1 protein contained the conserved beta-lactamase domain in its internal region. OsSnm1 was expressed in all rice organs. The expression was induced by MMS, H(2)O(2), and mitomycin C, but not by UV. Transient expression of an OsSnm1/GFP fusion protein in onion epidermal cells revealed the localization of OsSnm1 to the nucleus. These results suggest that OsSnm1 is involved not only in the repair of DNA interstrand crosslinks, but also in various other DNA repair pathways.     

Repeated administration of lead decreases brain 5-HT metabolism and produces memory deficits in rats

Long-term exposure to low levels of lead (Pb2+) has been shown to produce learning and memory deficits in rodents and humans. These deficits are thought to be associated with altered brain monoamine neurotransmission. Increased brain 5-HT (5-hydroxytryptamine; serotonin) activity is thought to be a prerequisite for maintaining control over the cognitive information process, and is said to have a role in learning and memory. This study was designed to investigate the effects of Pb2+ administration on brain 5-HT metabolism and memory function in rats. Rats were injected daily for three weeks with Pb2+-acetate at a dose of 100 mg/kg body weight. The assessment of memory was done using the Radial arm maze (RAM) and Passive avoidance tests. The results showed spatial working memory (SWM) deficits as well as decreased brain 5-HT metabolism. Increased serotonin activity is considered to be an indication of improved cognitive performance. The results are discussed in the context of lead-induced decreases in 5-HT metabolism playing a role in the impairment of memory.     

Opposing gradients of ephrin-As and EphA7 in the superior colliculus are essential for topographic mapping in the mammalian visual system

During development of the retinocollicular projection in mouse, retinal axons initially overshoot their future termination zones (TZs) in the superior colliculus (SC). The formation of TZs is initiated by interstitial branching at topographically appropriate positions. Ephrin-As are expressed in a decreasing posterior-to-anterior gradient in the SC, and they suppress branching posterior to future TZs. Here we investigate the role of an EphA7 gradient in the SC, which has the reverse orientation to the ephrin-A gradient. We find that in EphA7 mutant mice the retinocollicular map is disrupted, with nasal and temporal axons forming additional or extended TZs, respectively. In vitro, retinal axons are repelled from growing on EphA7-containing stripes. Our data support the idea that EphA7 is involved in suppressing branching anterior to future TZs. These findings suggest that opposing ephrin-A and EphA gradients are required for the proper development of the retinocollicular projection.     

Antimicrobial activities of Gloriosa superba Linn (Colchicaceae) extracts

The methanol extract of the rhizomes of Gloriosa superba Linn (Colchicaceae) and its subsequent fractions in different solvent systems were screened for antibacterial and antifungal activities. Excellent antifungal sensitivity was expressed by the n-butanol fraction against Candida albicans and Candida glaberata (up to 90%) and against Trichophyton longifusus (78%) followed by the chloroform fraction against Microsporum canis (80%). In the antibacterial bioassay, the crude extract and subsequent fractions showed mild to moderate antibacterial activities. Chloroform fraction displayed highest antibacterial sensitivity against Staphylococcus aureous (88%) followed by the crude extract (59%). The total phenol content of the crude extract and fractions of the plant expressed no significant correlation with the antimicrobial activities.     

Requirement of NOX2 Expression in Both Retina and Bone Marrow for Diabetes-Induced Retinal Vascular Injury

Objective

Diabetic retinopathy, a major cause of blindness, is characterized by increased expression of vascular endothelial growth factor (VEGF), leukocyte attachment to the vessel walls and increased vascular permeability. Previous work has shown that reactive oxygen species (ROS) produced by the superoxide generating enzyme NOX2/NADPH oxidase play a crucial role in the vascular pathology. The aim of this work was to identify the cellular sources of the damaging NOX2 activity by studies using bone marrow chimera mice.

Methods

Bone marrow cells were collected from the femurs and tibias of wild type and NOX2 deficient (NOX2^-/-) donor mice and injected intravenously into lethally irradiated NOX2^-/- and wild type recipients. Following recovery from radiation, mice were rendered diabetic by streptozotocin injections. The following groups of bone marrow chimeras were studied: non-diabetic WT→WT, diabetic WT→WT, diabetic WT→NOX2^-/-, diabetic NOX2^-/-→WT. After 4 weeks of diabetes, early signs of retinopathy were examined by measuring ROS, expression of VEGF and ICAM-1, leukocyte attachment to the vessel wall and vascular permeability.

Results

The retinas of the diabetic WT→WT chimeras showed significant increases in ROS as compared with the non-diabetic chimeras. These diabetes-induced alterations were correlated with increases in expression of VEGF and ICAM-1, leukocyte adhesion and vascular permeability. Each of these diabetes-induced alterations were significantly attenuated in the diabetic WT→NOX2^-/- and NOX2^-/-→WT chimera groups (p<0.05).

Conclusion

NOX2-generated ROS produced by both bone marrow-derived cells and resident retinal cells contribute importantly to retinal vascular injury in the diabetic retina. Targeting NOX2 in bone marrow and/or retinal cells may represent a novel therapeutic strategy for the treatment/prevention of vascular injury in the diabetic retina.     

Co-Expression of SERCA Isoforms,Phospholamban and Sarcolipin in Human Skeletal Muscle Fibers

Sarcolipin (SLN) and phospholamban (PLN) inhibit the activity of sarco(endo)plasmic reticulum Ca²⁺-ATPases (SERCAs) by reducing their apparent affinity for Ca²⁺. A ternary complex between SLN, PLN, and SERCAs results in super-inhibition of SERCA activity. Analysis of skeletal muscle homogenate has limited our current understanding of whether SLN and PLN regulate SERCA1a, SERCA2a, or both in skeletal muscle and whether SLN and PLN are co-expressed in skeletal muscle fibers. Biopsies from human vastus lateralis were analyzed through single fiber Western blotting and immunohisto/fluorescence staining to circumvent this limitation. With a newly generated SLN antibody, we report for the first time that SLN protein is present in human skeletal muscle. Addition of the SLN antibody (50 µg) to vastus lateralis homogenates increased the apparent Ca²⁺ affinity of SERCA (K _Ca, pCa units) (-Ab, 5.85 ± 0.02 vs. +Ab, 5.95 ± 0.02) and maximal SERCA activity (μmol/g protein/min) (-Ab, 122 ± 6.4 vs. +Ab, 159 ± 11) demonstrating a functional interaction between SLN and SERCAs in human vastus lateralis. Specifically, our results suggest that although SLN and PLN may preferentially regulate SERCA1a, and SERCA2a, respectively, physiologically they both may regulate either SERCA isoform. Furthermore, we show that SLN and PLN co-immunoprecipitate in human vastus lateralis homogenate and are simultaneously expressed in 81% of the fibers analyzed with Western blotting which implies that super-inhibition of SERCA may exist in human skeletal muscle. Finally, we demonstrate unequivocally that mouse soleus contains PLN protein suggesting that super-inhibition of SERCA may also be important physiologically in rodent skeletal muscle.     

Marine heatwaves reveal coral reef zones susceptible to bleaching in the Red Sea

As the Earth's temperature continues to rise, coral bleaching events become more frequent. Some of the most affected reef ecosystems are located in poorly monitored waters, and thus, the extent of the damage is unknown. We propose the use of marine heatwaves (MHWs) as a new approach for detecting coral reef zones susceptible to bleaching, using the Red Sea as a model system. Red Sea corals are exceptionally heat‐resistant, yet bleaching events have increased in frequency. By applying a strict definition of MHWs on >30 year satellite‐derived sea surface temperature observations (1985–2015), we provide an atlas of MHW hotspots over the Red Sea coral reef zones, which includes all MHWs that caused major coral bleaching. We found that: (a) if tuned to a specific set of conditions, MHWs identify all areas where coral bleaching has previously been reported; (b) those conditions extended farther and occurred more often than bleaching was reported; and (c) an emergent pattern of extreme warming events is evident in the northern Red Sea (since 1998), a region until now thought to be a thermal refuge for corals. We argue that bleaching in the Red Sea may be vastly underrepresented. Additionally, although northern Red Sea corals exhibit remarkably high thermal resistance, the rapidly rising incidence of MHWs of high intensity indicates this region may not remain a thermal refuge much longer. As our regionally tuned MHW algorithm was capable of isolating all extreme warming events that have led to documented coral bleaching in the Red Sea, we propose that this approach could be used to reveal bleaching‐prone regions in other data‐limited tropical regions. It may thus prove a highly valuable tool for policymakers to optimize the sustainable management of coastal economic zones.     

BECN1 is involved in the initiation of mitophagy: It facilitates PARK2 translocation to mitochondria

The autophagy protein BECN1/Beclin 1 is known to play a central role in autophagosome formation and maturation. The results presented here demonstrate that BECN1 interacts with the Parkinson disease-related protein PARK2. This interaction does not require PARK2 translocation to mitochondria and occurs mostly in cytosol. However, our results suggest that BECN1 is involved in PARK2 translocation to mitochondria because loss of BECN1 inhibits CCCP- or PINK1 overexpression-induced PARK2 translocation. Our results also demonstrate that the observed PARK2-BECN1 interaction is functionally important. Measurements of the level of MFN2 (mitofusin 2), a PARK2 substrate, demonstrate that depletion of BECN1 prevents PARK2 translocation-induced MFN2 ubiquitination and loss. BECN1 depletion also rescues the MFN2 loss-induced suppression of mitochondrial fusion. In sum, our results demonstrate that BECN1 interacts with PARK2 and regulates PARK2 translocation to mitochondria as well as PARK2-induced mitophagy prior to autophagosome formation.