A strategy for high cell density culture of heterotrophic microalgae with inhibitory substrates

Substrate inhibition is one of the major problems preventing high cell densities of microalgae in heterotrophic culture, so the possibility of overcoming the problem by various culture techniques was examined. It was found that perfusion culture may be the most appropriate technique for high cell densities in heterotrophic culture using inhibitory substrates. An experimental example in which a hollow fibre cell recycle system (HFCRS) was employed to achieve high cell densities of Chlamydomonas reinhardtii on acetate under heterotrophic conditions of growth was demonstrated. The cell density in the HFCRS was much higher than that reported in the literature for this species.     

Twilight activity patterns and angling vulnerability of yellowmouth barracuda (Sphyraena viridensis Cuvier, 1829), a range-expanding thermophilic fish

Among the thermophilic fishes that have become established in the north-western Mediterranean as a consequence of sea warming, the yellowmouth barracuda (Sphyraena viridensis Cuvier, 1829) appears to be one of the most successful and abundant in the coastal rocky environment, having increasingly become the object of recreational and commercial exploitation in the study area. Lure-fishing sessions were carried out from May 2016 to November 2018 in the Catalan Sea (NE Spain) at dawn and dusk, with the aim of providing new insight into the behavioural, spatial and feeding ecology and vulnerability to angling of this poorly known species. Generalized mixed-effects linear models showed that S. viridensis is a crepuscular inshore dweller, whose vulnerability to angling is significantly influenced by solar and lunar light intensities, being highest in the pre-spawn and spawning periods. Asymmetries between dawn and dusk activity patterns were detected, evidently related to a drop in aggressiveness at dusk following the spawning period. The simple study design adopted may be applied to other contexts, aiming to the recognition of several levels of fish vulnerability to angling.     

Impact of Sr2+ and hypoxia on 3D triple cultures of primary human osteoblasts,osteocytes and osteoclasts

An in vitro bone triple culture involving human primary osteoblasts, osteocytes and osteoclasts enables the investigation of bone healing factors, drugs or biomaterials in a model system for native bone tissue. The present study analyses the impact of Sr²⁺ as well as hypoxic cultivation (5% O₂ content or chemically induced by Co²⁺) on bone cells. The three cell types were cultivated together in the presence of 100 µM Sr²⁺, hypoxic conditions or in the presence of 75 µM Co²⁺. After cultivation the cell types were separated and analysed on mRNA and protein level individually. In response to Sr²⁺ osteoblasts showed a downregulation of IBSP expression and a stimulation of ALP activity. Osteocyte gene marker expression of PDPN, MEPE, RANKL, OPG, osteocalcin and likewise the amount of secreted osteocalcin was reduced in the presence of Sr²⁺. Activity of osteoclast-specific enzymes TRAP and CAII was enhanced compared to the Sr²⁺ free control. Hypoxic conditions induced by both 5% O₂ or a Co²⁺ treatment led to decreased DNA content of all bone cells and downregulated expression of osteoblast markers ALPL and IBSP as well as osteocyte markers PDPN, RANKL and OPG. In addition, Co²⁺ induced hypoxia decreased gene and protein expression of osteocalcin in osteocytes. In response to the Co²⁺ treatment, the TRAP gene expression and activity was increased. This study is the first to analyse the effects of Sr²⁺ or hypoxia on triple cultures with primary human bone cells. The investigated in vitro bone model might be suitable to reduce animal experiments in early stages of biomaterial and drug development.     

Elimination of apple stem grooving virus by chemotherapy and development of an immunocapture RT-PCR for rapid sensitive screening

Ombuin (7,4′-dimethyl quercetin) (10 μg ml^-1, for 12 wk), glycyrrhizin/quercetin (80 μg ml^-1and 10 μg ml^-1respectively, for 18 wk), ribavirin (10 μg ml^-1, for 12 wk) and quercetin/ribavirin (10 μg ml^-1each, for 9–12 wk) reduced the titre of apple stem grooving virus (ASGV) when applied in vitro to infected tissue cultures of Nicotiana occidentalis obliqua Wheeler, and/or Malus domestica. ASGV was not detectable in both plant species after the quercitin/ribavirin treatment when tested by ISEM, herbaceous host indexing, RT-PCR, and immunocapture RT-PCR. A sensitive immunocapture RT-PCR procedure for the detection of ASGV was developed for the screening of treated samples to assess antiviral activity.     

Production of entomopathogenic nematodes in submerged monoxenic culture: A review

Monoxenic liquid culture is the most suitable technology for scaling up to industrial production of entomopathogenic nematodes (EPNs); however, the variability of the yield production remains a current problem in the process. The aim of this study was to analyze the parameters and criteria for EPN production in liquid culture based on scientific and technological knowledge from the last two decades. While experimental research has permitted the yield production of Heterorhabditis bacteriophora (362 × 10³ infective juveniles [IJs]/ml) and Steinernema carpocapsae (252 × 10³ IJs/ml), simultaneously, theoretical approaches have contributed to the understanding of the culture process, based on biological parameters of the bacterium–nematode complex and hydrodynamic and rheological parameters of the complex gas–liquid–solid system. Under this interdisciplinary research approach, bioprocess and biosystem engineering can contribute to design the various control strategies of the process variables, increase the productivity, and reduce the variability that until now distinguishes the in vitro production of EPNs by the liquid culture.     

Striking difference in response to expanding brood parasites by birds in western and eastern Beringia

Two species of obligate brood‐parasitic Cuculus cuckoos are expanding their ranges in Beringia. Both now breed on the Asian side, close to the Bering Strait, and are found in Alaska during the breeding season. From May to July 2017, we used painted 3D‐printed model eggs of two cuckoo host‐races breeding in northeastern Siberia to test behavioral responses of native songbirds on both sides of the Bering Strait, with particular attention to species that are known cuckoo hosts in their Siberian range. Each host nest was tested after the second egg was laid and, if possible, again 4 days later with a model of a different type. Although our Siberian study site was also outside the known breeding ranges of the cuckoos, we found that Siberian birds had strong anti‐parasite responses, with 14 of 22 models rejected. In contrast, birds in Alaska had virtually no detectable anti‐parasite behaviors, with only one of 96 models rejected; the rejecters were Red‐throated Pipits (Anthus cervinus). Such differences suggest that the cuckoos might successfully parasitize naïve hosts and become established in North America whether or not their historic host species are widely available.     

Plant-derived smoke solutions stimulate the growth of Lycopersicon esculentum roots in vitro

Aqueous extracts of smoke, derived from Themeda triandra, a fire-climax grass, and Passerina vulgaris, a fynbos plant, stimulated the growth of primary root sections of tomato roots in suspension culture. The optimal dilution for both extracts was 1:2000. Several of the fractions obtained from TLC separation of the Themeda and the Passerina extracts significantly promoted primary root growth. The auxins naphthaleneacetic acid (NAA), indolebutyric acid (IBA) and indoleacetic acid (IAA) were found to stimulate the growth of the primary root axis, with IAA and NAA significantly promoting lateral root number. Similarly, the naturally occurring cytokinins, zeatin and its derivatives (zeatin-O-glucoside; dihydrozeatin and zeatin riboside) stimulated primary root length. Zeatin and dihydrozeatin promoted secondary root growth, but only at very low concentrations.     

Mediator structure and conformation change

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A method for the harvest,culture, and characterization of human adult atrial myocardial cells: Correlation with age of donor

Summary Myocardial cell culture methods are now well established for animal and fetal human tissue. We present here a method for harvesting and culturing adult human atrial myocardiocytes. Cells are obtained from fresh atrial tissue normally discarded after being removed to cannulate the right atrium during open heart surgery. The atrial tissue is minced and then digested using collagenase. The single cell suspension is initially cultured in serum-containing growth medium, then transferred to defined medium, selective for myocardial cell growth. The cells are characterized by immunoperoxidase stains and transmission electron microscopy. The cultured cells stain positive for myoglobin, whereas control cultured fibroblasts and endothelial cells do not. Electron microscopy shows the presence of numerous myofibrils, Z-bodies, pleomorphic mitochondria, and secretory granules. The chronological age of the donor was an important factor in culturing the adult tissue, the younger tissue correlated with a higher success rate. This method provides a means for in vitro study of human adult myocardial cells and provides guidelines for appropriate atrial tissue to use.