Effect of mixing on biogas production during mesophilic anaerobic digestion of screened dairy manure in a pilot plant

The effect of mixing on biogas production of a 1.5‐m³ pilot continuous stirred tank reactor (CSTR) processing screened dairy manure was evaluated. Mixing was carried out by recirculation of reactor content with a mono pump. The experiment was conducted at a controlled temperature of 37±1°C and hydraulic retention times (HRTs) of 20 and 10 days. The effect of continuous and intermittent operation of the recirculation pump on biogas production was studied. At 10 days of HRT, the results showed a minimal influence of recirculation rate on biogas production and that continuous recirculation did not improve reactor performance. At 20 days of HRT, the recirculation rate did not affect reactor performance. Combination of low solid content in feed animal slurry and long HRTs results in minimal mixing requirements for anaerobic digestion.     

The feeding apparatus of a chitinivorous ciliate

The chitinivorous ciliate Ascophrys, an ectosymbiont of the shrimp Palaemon serratus, is enclosed by a thick cyst wall except for a ventral hiatus exposing a circular area of exoskeleton to the interior of the cyst. The exoskeleton underlying the cyst wall remains intact, but the circular area of exoskeleton is dissolved enzymatically and ingested. The feeding ciliate forms a cavity in the exoskeleton into which it sinks. Its complex oral apparatus resembles a pump encircled by cytoplasm containing Golgi and high concentrations of coated vesicles that join pellicular pores between cilia. The ingestive apparatus is formed of microtubular lamellae that originate in the midplane of the body, descend toward a coated membrane on the surface, and ascend again as a lamellar lining to a complex food tube that ends in the middle of the body surrounded by food vacuoles. The cytoplasm enclosed between the descending lamellae and the food tube is crowded with membrane organelles that recycle as food vacuole membranes at the coated membrane. We hypothesize that vacuoles containing dissolved exoskeleton are drawn up into the oral tube and are released into the cytoplasm at the terminus of the tube, where their contents are concentrated and excess vacuolar membrane collapsed into membrane organelles.     

Melatonin controls cell proliferation and modulates mitochondrial physiology in pancreatic stellate cells

Journal of Physiology and Biochemistry - We have investigated the effects of melatonin on major pathways related with cellular proliferation and energetic metabolism in pancreatic stellate cells....     

Occurrence of 9.5 cellulase and other hydrolases in flower reproductive organs undergoing major cell wall disruption

The occurrence of enzymes associated with bean leaf abscission was investigated in bean (Phaseolus vulgaris) flower reproductive organs in which catabolic cell wall events are essential during anther and pistil development. Cellulase activity was detected in high levels in both pistil and anthers of bean flowers before anthesis. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by immunoblotting with 9.5 cellulase antibody identified a protein in anthers and pistil with the same size (51 kilodaltons) and serologically closely related to the abscission cellulase. The accumulation of 9.5 cellulase protein in the anther is developmentally regulated and increases from undetectable levels at very young stages of anther development to high levels as the anther matures. In the pistil, the 9.5 cellulase was localized in the upper part of the pistil where the stigma and the stylar neck reside and was detected in the youngest developmental stage analyzed. Antibodies against basic chitinase, which accumulates to high levels in abscission zones after exposure to ethylene, identified a protein with the same size (33 kilodaltons) and serologically closely related, in both anthers and upper portion of the pistil. In contrast, a 45-kilodalton protein and the basic β-1,3-glucanase associated with abscission were undetected in bean reproductive organs. Interestingly, β-1,3-glucanase activity was detected in young bean anthers and decreased at anthesis, but the anther β-1,3-glucanase is serologically unrelated to the basic β-1,3-glucanase. Thus, it appears that the basic cellulase and chitinase occur in combination in many plant processes that require major cell wall disruption, whereas hemicellulases such as β-1,3-glucanase are specific to each process.     

Molecular properties of the enzymic phytohemagglutinin of mung bean

Mung bean seeds possess a tetrameric galactose-binding protein that displays two types of activities: (a) a hemagglutinin activity, and (b) an alpha-galactosidase activity. This protein can be reversibly converted by pH changes from a tetrameric form, which possesses both enzymic and hemagglutinin activities, to a monomeric form which possesses enzymic activity only. This observation suggests that the enzymic phytohemagglutinin is an aggregated form of a monomeric alpha-galactosidase. The tetrameric alpha-galactosidase has a pH optimum of about pH 7.0, while the monomeric form displays a pH optimum of 5.6. Circular dichroism difference spectra and inhibition studies suggest that aggregation induces conformational changes in the subunits sufficient to alter their enzymatic properties. The possibility of in vivo changes in subunit equilibria, when combined with the accompanying alterations in activity, provides a new concept worthy of consideration with respect to the physiological role of phytohemagglutinins.     

Regional Brain Atrophy and Functional Connectivity Changes Related to Fatigue in Multiple Sclerosis

Fatigue is one of the most frequent symptoms in multiple sclerosis (MS), and recent studies have described a relationship between the sensorimotor cortex and its afferent and efferent pathways as a substrate of fatigue. The objectives of this study were to assess the neural correlates of fatigue in MS through gray matter (GM) and white matter (WM) atrophy, and resting state functional connectivity (rs-FC) of the sensorimotor network (SMN). Eighteen healthy controls (HCs) and 60 relapsing-remitting patients were assessed with the Fatigue Severity Scale (FSS). Patients were classified as fatigued (F) or nonfatigued (NF). We investigated GM and WM atrophy using voxel-based morphometry, and rs-FC changes with a seed-based method and independent component analysis (ICA). F patients showed extended GM and WM atrophy focused on areas related to the SMN. High FSS scores were associated with reductions of WM in the supplementary motor area. Seed analysis of GM atrophy in the SMN showed that HCs presented increased rs-FC between the primary motor and somatosensory cortices while patients with high FSS scores were associated with decreased rs-FC between the supplementary motor area and associative somatosensory cortex. ICA results showed that NF patients presented higher rs-FC in the primary motor cortex compared to HCs and in the premotor cortex compared to F patients. Atrophy reduced functional connectivity in SMN pathways and MS patients consequently experienced high levels of fatigue. On the contrary, NF patients experienced high synchronization in this network that could be interpreted as a compensatory mechanism to reduce fatigue sensation.     

A New Ichnospecies of Arthrophycus from the Upper Cambrian-Lower Tremadocian of Northwest Argentina: Implications for the Arthrophycid Lineage and Potential in Ichnostratigraphy

A new ichnospecies of Arthrophycus Hall 1852, A. minimus , is described from Upper Cambrian-Lower Tremadocian, shallow-marine strata of northwest Argentina. This new ichnospecies consists of small, long, regularly annulated hypichnial elements displaying subcircular to squarish cross-section and a ventral median groove. Side branches are occasionally present, but palmate, fan-like structures and scribbling patterns are absent. We adopt a relatively narrow diagnosis of Arthrophycus , suggesting that roughly annulated, cylindrical structures should not be included in this ichnogenus, unless other diagnostic features (i.e., squarish cross-section, median groove, zipper-like annulations) are also present. Arthrophycus is a common ichnotaxon in Ordovician-Silurian shallow-marine siliciclastic environments. Post-Paleozoic occurrences are removed from Arthrophycus . Arthrophycus has been proposed as a biostratigraphic index fossil in Ordovician-Silurian rocks. The presence of A. minimus in the Santa Rosita Formation of northwest Argentina indicates that Arthrophycus ranges at least from the Upper Cambrian-Lower Tremadocian with probable representatives in the Lower Cambrian and, therefore, its biostratigraphic utility is extended. Arthrophycus minimus represents the first Cambrian occurrence exhibiting not only fine, diagnostic morphologic features, but also the classical Arthrophycus behavioral pattern in dense monoichnospecific assemblages. The exploratory behavioral pattern displayed by A. minimus is simpler than that of the younger ichnospecies, particularly A. brogniartii, A. alleghaniensis, and A. lateralis . This is consistent with the basal position of A. minimus within the arthrophycid lineage.     

Tailoring translational strength using Kozak sequence variants improves bispecific antibody assembly and reduces product-related impurities in CHO cells

Optimal production of bispecific antibodies (bsAb) requires efficient and tailored co-expression and assembly of two distinct heavy and two distinct light chains. Here, we describe a novel technology to modulate the translational strength of antibody chains via Kozak sequence variants to produce bsAb in a single cell line. In this study, we designed and screened a large Kozak sequence library to identify 10 independent variants that can modulate protein expression levels from approximately 0.2 to 1.3-fold compared with the wild-type sequence in transient transfection. We used a combination of several of these variants, covering a wide range of translational strength, to develop stable single cell Chinese hamster ovary bispecific cell lines and compared the results with those obtained from the wild-type sequence. A significant increase in bispecific antibody assembly with a concomitant reduction in the level of product-related impurities was observed. Our findings suggest that for production of bsAb it can be advantageous to modify translational strength for selected protein chains to improve overall yield and product quality. By extension, tuning of translational strength can also be applied to improving the production of a wide variety of heterologous proteins.