Phospho-eIF2α level is important for determining abilities of BACE1 reduction to rescue cholinergic neurodegeneration and memory defects in 5XFAD mice

β-Site APP-cleaving enzyme 1 (BACE1) initiates amyloid-β (Aβ) generation and thus represents a prime therapeutic target in treating Alzheimer's disease (AD). Notably, increasing evidence indicates that BACE1 levels become elevated in AD brains as disease progresses; however, it remains unclear how the BACE1 upregulation may affect efficacies of therapeutic interventions including BACE1-inhibiting approaches. Here, we crossed heterozygous BACE1 knockout mice with AD transgenic mice (5XFAD model) and compared the abilities of partial BACE1 reduction to rescue AD-like phenotypes at earlier (6-month-old) and advanced (15-18-month-old) stages of disease, which expressed normal (～100%) and elevated (～200%) levels of BACE1, respectively. BACE1(+/-) deletion rescued memory deficits as tested by the spontaneous alternation Y-maze task in 5XFAD mice at the earlier stage and prevented their septohippocampal cholinergic deficits associated with significant neuronal loss. Importantly, BACE1(+/-) deletion was no longer able to rescue memory deficits or cholinergic neurodegeneration in 5XFAD mice at the advanced stage. Moreover, BACE1(+/-) deletion significantly reduced levels of Aβ42 and the β-secretase-cleaved C-terminal fragment (C99) in 6-month-old 5XFAD mouse brains, while these neurotoxic β-cleavage products dramatically elevated with age and were not affected by BACE1(+/-) deletion in 15-18-month-old 5XFAD brains. Interestingly, although BACE1(+/-) deletion lowered BACE1 expression by ～50% in 5XFAD mice irrespective of age in concordance with the reduction in gene copy number, BACE1 equivalent to wild-type controls remained in BACE1(+/-)·5XFAD mice at the advanced age. In accord, phosphorylation of the translation initiation factor eIF2α, an important mediator of BACE1 elevation, was dramatically increased (～9-fold) in 15-18-month-old 5XFAD mice and remained highly upregulated (～6-fold) in age-matched BACE1(+/-)·5XFAD mice. Together, our results indicate that partial reduction of BACE1 is not sufficient to block the phospho-eIF2α-dependent BACE1 elevation during the progression of AD, thus limiting its abilities to reduce cerebral Aβ/C99 levels and rescue memory deficits and cholinergic neurodegeneration.     

Fungal Biofilms in the Clinical Lab Setting

Device-related infections are often associated with biofilms (microbial communities encased within polysaccharide-rich extracellular matrix) formed by pathogens on surfaces of these devices. Candida species are the most common fungi isolated from infections associated with catheters and dentures, and both Candida and Fusarium are commonly isolated from contact lens–related infections such as fungal keratitis. These biofilms exhibit decreased susceptibility to most antimicrobial agents, which contributes to the persistence of infection. Drug resistance in fungal biofilms is multifactorial and phase-dependent; for example, efflux pumps mediate resistance in biofilms during early phase, whereas altered membrane sterol composition contributes to resistance in mature phase. Both substrate type and surface coatings play an important role in the pathogenesis of device-related fungal biofilms. Host immune cells influence the ability of Candida to form biofilms in vitro. This review summarizes recent advances in research on fungal biofilms and discusses their clinical relevance.     

Fucoxanthin induced apoptotic cell death in oral squamous carcinoma (KB) cells

Fucoxanthin (Fx) is an active compound commonly found in the many types of seaweed with numerous biological activities. The main goal of this investigation is to explore the effect of Fx against the cell proliferation, apoptotic induction and oxidative stress in the oral squamous (KB) cell line. Cytotoxicity of Fx was determined by MTT assay. The intracellular ROS production, mitochondrial membrane potential (MMP) and apoptosis induction in KB cells were examined through DCFH-DA, Rhodamine-123 and DAPI, and dual staining techniques. Effect of Fx on the antioxidant enzymes and lipid peroxidation in the KB cells was studied through the standard procedures. Fx treated KB cells showed morphological changes and reduced cell survival, which is exhibited by the cytotoxic activity of 50 µM/ml (IC50) Fx against the KB cells. The Fx treatment considerably induced the apoptotosis cells (EB/AO) and decreased the MMP (Rh-123) in KB cells. Further, it was pointed out that there was an increased lipid peroxidation (LPO) with decreased antioxidants (CAT, SOD and GSH). These results concluded that Fx has the cytotoxic effect against KB cells and has the potential to induce the apoptosis via increased oxidative stress. Hence, the Fx can be a promising agent for the treatment of oral cancer and it may lead to the development of cancer therapeutics.     

Localization of intracellular zinc under conditions of altered permeability control of the plasma membrane

Intracellular zinc was located as electron dense granules associated with the plasma membrane, endoplasmic reticular membranes, mitochondrial membranes, nuclear membranes and chromatin in Zajdela ascitic hepatoma and AK5 macrophage ascitic tumour cells. The quantity of intracellular zinc estimated by atomic emission spectrometer was different in the two cell lines. However, after loss of permeability control by the plasma membrane, involving glutaraldehyde and heat-shock treatments, the quantity of intracellular zinc was increased to almost the same extent in both cases.     

Inbreeding and post-natal mortality in South India: Effects on the gene pool

Consanguineous marriages have been favoured throughout South India for many generations. On theoretical grounds it was proposed that long-term inbreeding would have resulted in the elimination of deleterious, recessive lethal and sub-lethal genes. As part of a newborn screening programme for amino acidopathies, data were collected on the level of inbreeding in the current populations of the cities of Bangalore and Mysore, and on the relationship between consanguinity and mean numbers of liveborn and living children. Mean cnonsanguinity was 32.24%, equivalent to a cuoefficient of inbreeding in the newborns,F = 00271. There were no significant differences between the various inbreeding classes in the number of liveborn or living children, nor was a significant consanguinity-related effect on the proportion of survivors detectable. In the light of these findings, the effects on the gene pool of multiple generations of inbreeding are discussed.     

Conformational changes in DNA and soft modes

In this paper we explore the applicability of the soft mode approach to study the conformational transitions of DNA. It is believed that the A-B conformation change is a first order transition. Soft mode theories only apply to the initial stages of a first order transition. However the mode softening in such a case can be the initiating factor which ultimately leads to the transition. The first order transition is, then, a breakdown of what otherwise would have been a true second order transition. The mode softening is causally connected to onset of the transition. We use the eigenvectors obtained from lattice dynamics calculations to identify the softmode. We use the eigenvector projections to form a force constant matrix that is required to drive a mode soft. We explore the methods by which this force constant matrix can be formed. We suggest that the breaking of specific "water bridges" between phosphate groups in the two single strands can drive the conformation change.     

A seasonal study of the red seaweeds Solieria tenera and three species of Gracilaria from Jamaica

Three species of Gracilaria viz G. cervicornis, G. domingensis, G. verrucosa and Solieria tenera (Gigartinales, Rhodophyta) have been studied for their monthly variation in dry wt yields, ash, soluble carbohydrate, protein, lipid and insoluble carbohydrate contents for one year. The dry wt yields were higher in G. domingensis. Soluble carbohydrate and ash contents showed an inverse relationship in all the species. Protein content was lower, below 5% of the dry wt for all the species. A comparison of protein:carbohydrate ratios showed a similarity between morphologically similar G. domingensis and G. cervicornis in that there was less variation in the ratio. From this, it is assumed that flattened morphology probably is more efficient in maintaining nutrient balance to keep up the growth rates.     

Hemin-mediated oxidative inactivation of 3-hydroxy-3-methylglutaryl CoA reductase

Summary Addition of hemoglobin, methemoglobin, hemin or hematin in the assay mixture of rat liver 3-hydroxy-3-methylglutaryl CoA (HMGCoA) reductase inhibited the activity of the enzyme. The inhibition by hemin was rapid, without any apparent dependence on time of preincubation. At 20 M hemin, a maximum of about 50% inhibition was obtained in the case of the microsomal enzyme while the solubilized enzyme showed almost 80%6 inhibition. Dithiothreitol at high concentrations or either of the two substrates of the enzyme (HMGCoA and NADPH) could afford partial protection when added before hemin. The K_m for both the substrates increased in the presence of hemin. The inhibition by hemin appeared to be irreversible, the presence of KCN or NaN₃ being the only means of preventing the inhibition. Molecular oxygen was required for the inhibition. Oxygen radicals and H₂O₂, however, did not seem to be involved. This offered a clue that an oxidation reaction of the reductase protein may be the likely mechanism of its inactivation. The enzyme protein did not, however, get degraded under the conditions of inhibition.Abbreviations HMGCoA 3-Hydroxy-3-methylglutaryl coenzyme - DTT Dithiothreitol - DTNB 5,5-Dithiobis-(2-nitrobenzoic acid) - SDS-PAGE Sodium dodecyl sulphate-polyacrylamide gel electrophoresis     

Molecular cloning and characterization of endogenous feline leukemia virus sequences from a cat genomic library.

Recombinant bacteriophage lambda clones from a cat genomic library derived from placental DNA of a specific pathogen-free cat were screened to identify endogenous feline leukemia virus (FeLV) sequences. Restriction endonuclease mapping of four different clones indicates that there are a number of similarities among them, notably the presence of a 6.0- to 6.4-kilobase pair (kbp) EcoRI hybridizing fragment containing portions of sequences homologous to the gag, pol, env, and long terminal repeat-like elements of the infectious FeLV. The endogenous FeLV sequences isolated are approximately 4 kbp in length and are significantly shorter than the cloned infectious FeLV isolates, which are 8.5 to 8.7 kbp in length. The endogenous elements have 3.3- to 3.6-kbp deletions in the gag-pol region and approximately 0.7- to 1.0-kbp deletions in the env region. These deletions would render them incapable of encoding an infectious virus and may therefore be related to the non-inducibility of FeLV from uninfected cat cells and the subgenomic expression of these endogenous sequences in placental tissue. It appears that there is conservation in the ordering of restriction sites previously reported in the proviruses of the infectious FeLVs in sequences corresponding to the pol and env boundary as well as the region spanning the env gene of the endogenous clones, whereas a greater divergence occurs among restriction sites mapped to the gag and part of the pol regions of the infectious FeLV. Such deleted, FeLV-related subsets of DNA sequences could have originated either by germ-line integration of a complete ecotropic virus followed by deletion, or by integration of a preexisting, defective, deleted variant of the infectious virus.     

Inhibition of 3-hydroxy-3-methylglutaryl coenzyme a reductase by cytosolic proteins - real or artifact

The inhibitory effect of FeSO₄-dependent cytosolic protein on microsomal HMGCoA reductase is on the enzyme activity and not an artifact of loss of the product, mevalonate, through phosphorylation, unlike that of ATP.Mg effect.