Fairy, tadpole, and clam shrimps (Branchiopoda) in seasonally inundated clay pans in the western Mojave Desert and effect on primary producers

Background

Fairy shrimps (Anostraca), tadpole shrimps (Notostraca), clam shrimps (Spinicaudata), algae (primarily filamentous blue-green algae [cyanobacteria]), and suspended organic particulates are dominant food web components of the seasonally inundated pans and playas of the western Mojave Desert in California. We examined the extent to which these branchiopods controlled algal abundance and species composition in clay pans between Rosamond and Rogers Dry Lakes. We surveyed branchiopods during the wet season to estimate abundances and then conducted a laboratory microcosm experiment, in which dried sediment containing cysts and the overlying algal crust were inundated and cultured. Microcosm trials were run with and without shrimps; each type of trial was run for two lengths of time: 30 and 60 days. We estimated the effect of shrimps on algae by measuring chlorophyll content and the relative abundance of algal species.

Results

We found two species of fairy shrimps (Branchinecta mackini and B. gigas), one tadpole shrimp (Lepidurus lemmoni), and a clam shrimp (Cyzicus setosa) in our wet-season field survey. We collected Branchinecta lindahli in a pilot study, but not subsequently. The dominant taxa were C. setosa and B. mackini, but abundances and species composition varied greatly among playas. The same species found in field surveys also occurred in the microcosm experiment. There were no significant differences as a function of experimental treatments for either chlorophyll content or algal species composition (Microcoleus vaginatus dominated all treatments).

Conclusions

The results suggest that there was no direct effect of shrimps on algae. Although the pans harbored an apparently high abundance of branchiopods, these animals had little role in regulating primary producers in this environment.     

Radiofrequency ablation of premature ventricular contractions originating from uncommon sites of right ventricle

Premature Ventricular Contraction (PVC)/ventricular tachycardia (VT) with left bundle branch block (LBBB) morphology and inferior axis has been described classically to originate from the right ventricular outflow tract (RVOT). Some uncommon sites of idiopathic ventricular arrhythmia (VA) origins have been revealed including tricuspid annulus (TA) and right ventricular (RV) inflow free wall region. We present a series of two cases who have undergone electrophysiological study and successful radiofrequency ablation of frequent monomorphic PVCs with LBBB pattern originating from relatively uncommon sites of RV – TA and RV inflow free wall region.     

Mefenamic Acid Attenuates Chronic Alcohol Induced Cognitive Impairment in Zebrafish: Possible Role of Cholinergic Pathway

Based on the scientific evidence supporting the neuroinflammatory response contributes the cognitive impairment associated with chronic alcoholism and the neuroprotective actions of mefenamic acid with reversal of memory loss and brain inflammation in mice, this study was designed to evaluate the effect of mefenamic acid against chronic alcohol induced cognitive impairment in zebrafish model. Zebrafish were grouped and subjected to normal behavioral analysis in light–dark chamber for 10 days. The preference to dark compartment was noted in zebrafish. Zebrafish were grouped and exposed to escalating doses of alcohol for 28 days with and without mefenamic acid exposure (100 and 200 µg/L) and subjected to a fear conditioning passive avoidance task from day 13 of 28. The cognitive evaluation was performed for 10 days and the brain tissue was isolated to estimate acetylcholinesterase activity. In cognitive evaluation study, the normal zebrafish retained the memory of the learned task and avoided the dark. The alcohol exposed zebrafish showed impairment in retaining the memory of learned task. Mefenamic acid exposed zebrafish showed a significant protection against cognitive impairment caused by alcohol and retained the memory of learned task with a significant decrease in AChE activity in brain homogenate compared to alcohol exposed zebrafish. The results of this study suggest that the memory enhancing activity of mefenamic acid might be due to activation of cholinergic transmission that has protected neuroinflammatory and neurodegenerative conditions caused by alcohol.     

Lipid rafts of primary endothelial cells are essential for Kaposi's sarcoma-associated herpesvirus/human herpesvirus 8-induced phosphatidylinositol 3-kinase and RhoA-GTPases critical for microtubule dynamics and nuclear delivery of viral DNA but dispensable for binding and entry

Early during de novo infection of human microvascular dermal endothelial (HMVEC-d) cells, Kaposi's sarcoma-associated herpesvirus (KSHV) (human herpesvirus 8 [HHV-8]) induces the host cell's preexisting FAK, Src, phosphatidylinositol 3-kinase (PI3-K), Rho-GTPases, Diaphanous-2 (Dia-2), Ezrin, protein kinase C-zeta, extracellular signal-regulated kinase 1/2 (ERK1/2), and NF-kappaB signal pathways that are critical for virus entry, nuclear delivery of viral DNA, and initiation of viral gene expression. Since several of these signal molecules are known to be associated with lipid raft (LR) domains, we investigated the role of LR during KSHV infection of HMVEC-d cells. Pretreatment of cells with LR-disrupting agents methyl beta-cyclo dextrin (MbetaCD) or nystatin significantly inhibited the expression of viral latent (ORF73) and lytic (ORF50) genes. LR disruption did not affect KSHV binding but increased viral DNA internalization. In contrast, association of internalized viral capsids with microtubules (MTs) and the quantity of infected nucleus-associated viral DNA were significantly reduced. Disorganized and disrupted MTs and thick rounded plasma membranes were observed in MbetaCD-treated cells. LR disruption did not affect KSHV-induced FAK and ERK1/2 phosphorylation; in contrast, it increased the phosphorylation of Src, significantly reduced the KSHV-induced PI3-K and RhoA-GTPase and NF-kappaB activation, and reduced the colocalizations of PI3-K and RhoA-GTPase with LRs. Biochemical characterization demonstrated the association of activated PI3-K with LR fractions which was inhibited by MbetaCD treatment. RhoA-GTPase activation was inhibited by PI3-K inhibitors, demonstrating that PI3-K is upstream to RhoA-GTPase. In addition, colocalization of Dia-2, a RhoA-GTPase activated molecule involved in MT activation, with LR was reduced. KSHV-RhoA-GTPase mediated acetylation and aggregation of MTs were also reduced. Taken together, these studies suggest that LRs of endothelial cells play critical roles in KSHV infection and gene expression, probably due to their roles in modulating KSHV-induced PI3-K, RhoA-GTPase, and Dia-2 molecules essential for postbinding and entry stages of infection such as modulation of microtubular dynamics, movement of virus in the cytoplasm, and nuclear delivery of viral DNA.     

An unusual mechanism of sustained right atrial tachycardia

Lower loop re-entry (LLR) flutter is a rare type of atypical right atrial flutter. Most of the reported cases occurred in association with typical flutter patterns as a transient arrhythmia. Our case is unique in the fact the LLR was sustained and persisted independently.     

Investigation of interleukin-1β release from cryopreserved blood stimulated with endotoxin

The feasibility of an indigenously developed ELISA method to determine cytokine response to wide spectrum of pyrogenic stimuli utilizing fresh human whole blood is limited by the availability of healthy donors. The possibility of using cryopreservation of pooled human blood for detection of cytokine response to lipopolysaccharide is explored in this study. The effect of cryopreservation on blood parameters, cellular morphology and cytokine response were compared with that of the pooled fresh blood and cryopreserved blood from single and multiple donors. In vitro pyrogenic stimulation with 0.5 and 5 EU of LPS was monitored on fresh and cryopreserved pooled blood from single and multiple donors. The release of IL-1β was quantitated by Sandwich ELISA (1, 10, 25, 45 and 75 days) after storage. The results indicated that the cryopreserved blood displayed enhanced IL-1β release on stimulation with LPS, when compared to fresh blood. The maximum release of IL-1β level was observed at 2 h when 5 EU of LPS was treated with pooled fresh blood which is similar to that of fresh blood. After 75 days storage of pooled cryopreserved blood the IL-1β release was maximum at 9 and 15 h when treated with 5 and 0.5 EU of LPS. Observations of the study suggest that cryopreserved pooled blood is an economically and experimentally viable alternative to fresh blood. This investigative study promises short term storage and regular supply of non-allergic, pathogen free human blood for the detection of interleukin-1β for the evaluation of in vitro pyrogenicity.