Double C2 protein. A review

Concerted effort has led to the identification of dozens of synaptic proteins and has thereby opened the door for the characterisation of the molecular mechanisms underlying regulated exocytosis. Calcium is known to play a number of roles in regulated exocytosis, acting as the trigger for fast synaptic transmission and also acting at some of the steps preceding vesicle fusion. Investigators have therefore focussed considerable attention on possible calcium sensors. What many of the candidate proteins have in common is a C2 domain, one of the four conserved domains originally described in protein kinase C. Such domains have been shown to bind calcium and phospholipid in a large number of intracellular proteins. Synaptotagmin, a C2-domain protein, is a very strong candidate for the protein involved in triggering fast calcium-dependent vesicle fusion. Recent attention has also concerned the other calcium sensors, which may play roles in the 'priming' or transport of vesicles. This review concerns one of these tentative calcium-binding proteins, double C2 or DOC2. DOC2 was originally isolated from nervous tissue but subsequently has been found to be more widely expressed. DOC2 is a vesicular protein that may be involved in the early stages of preparing vesicles for exocytosis.     

Correlation of patellar tracking pattern with trochlear and retropatellar surface topographies

The study was aimed to test the hypothesis that in the knee extension range 100 to 30 deg, the patellar "out-of-plane" tracking pattern is controlled by the passive restraint provided by the topographic interaction of the patellofemoral contacting surfaces. The out-of-plane tracking pattern, i.e., the pattern of patellar displacements not in the plane of knee extension/flexion, consists of translation in the medial-lateral direction, and rotations about the anterior-posterior axis (spin) and the proximal-distal axis (tilt). Using 15 fresh-frozen knees subjected to extensor moment magnitudes comparable to those in the "static-lifting" activity (foot-ground reaction = 334 N), the patellar displacements were measured using a calibrated six-degree-of-freedom electromechanical goniometer. The topographies of the trochlear and retropatellar surfaces were then measured using a calibrated traveling dial-gage arrangement and the same coordinate system used for the displacement measurements. Three indices were defined to quantify particular natural features of the three-dimensional topographies that are expected to control the patellar displacements. Correlation of the indices with their corresponding displacements showed that topographic interaction was significant in the control of all three displacements. However, for patellar spin, unlike for the other two displacements, the direction of the active quadriceps tension vector was also a significant controlling factor. Patellar medial-lateral translation was found to be controlled dominantly by the trochlear topography, while retropatellar topography also had a significant role in the control of the other two displacements.     

Column sorption of Cr(VI) from electroplating effluent using formaldehyde cross-linked Saccharomyces cerevisiae

Pellets of Saccharomyces cerevisiae, cross-linked by 13% (w/v) formaldehyde, were used in fixed-bed columns to remove Cr(VI) from electroplating rinse effluent at varied influent pHs (2.5–7.5). The Cr uptake at 60% saturation of the biomass was 6.3 mg/g at an optimum pH of 2.5. Desorption of the bound metal was partially achieved by washing the column biomass with a combined solution of 1% (w/v) formaldehyde and 1 M HNO3. © Rapid Science Ltd. 1998     

The interaction of Saccharomyces paradoxus with its natural competitors on oak bark

The natural history of the model yeast Saccharomyces cerevisiae is poorly understood and confounded by domestication. In nature, S. cerevisiae and its undomesticated relative S. paradoxus are usually found on the bark of oak trees, a habitat very different from wine or other human fermentations. It is unclear whether the oak trees are really the primary habitat for wild yeast, or whether this apparent association is due to biased sampling. We use culturing and high‐throughput environmental sequencing to show that S. paradoxus is a very rare member of the oak bark microbial community. We find that S. paradoxus can grow well on sterile medium made from oak bark, but that its growth is strongly suppressed when the other members of the community are present. We purified a set of twelve common fungal and bacterial species from the oak bark community and tested how each affected the growth of S. paradoxus in direct competition on oak bark medium at summer and winter temperatures, identifying both positive and negative interactions. One Pseudomonas species produces a diffusible toxin that suppresses S. paradoxus as effectively as either the whole set of twelve species together or the complete community present in nonsterilized oak medium. Conversely, one of the twelve species, Mucilaginibacter sp., had the opposite effect and promoted S. paradoxus growth at low temperatures. We conclude that, in its natural oak tree habitat, S. paradoxus is a rare species whose success depends on the much more abundant microbial species surrounding it.     

Control of SARS-CoV-2 infection after Spike DNA or Spike DNA+Protein co-immunization in rhesus macaques

The speed of development, versatility and efficacy of mRNA-based vaccines have been amply demonstrated in the case of SARS-CoV-2. DNA vaccines represent an important alternative since they induce both humoral and cellular immune responses in animal models and in human trials. We tested the immunogenicity and protective efficacy of DNA-based vaccine regimens expressing different prefusion-stabilized Wuhan-Hu-1 SARS-CoV-2 Spike antigens upon intramuscular injection followed by electroporation in rhesus macaques. Different Spike DNA vaccine regimens induced antibodies that potently neutralized SARS-CoV-2 in vitro and elicited robust T cell responses. The antibodies recognized and potently neutralized a panel of different Spike variants including Alpha, Delta, Epsilon, Eta and A.23.1, but to a lesser extent Beta and Gamma. The DNA-only vaccine regimens were compared to a regimen that included co-immunization of Spike DNA and protein in the same anatomical site, the latter of which showed significant higher antibody responses. All vaccine regimens led to control of SARS-CoV-2 intranasal/intratracheal challenge and absence of virus dissemination to the lower respiratory tract. Vaccine-induced binding and neutralizing antibody titers and antibody-dependent cellular phagocytosis inversely correlated with transient virus levels in the nasal mucosa. Importantly, the Spike DNA+Protein co-immunization regimen induced the highest binding and neutralizing antibodies and showed the strongest control against SARS-CoV-2 challenge in rhesus macaques.     

Phenotypic and genotypic characterization of encapsulated Escherichia coli isolated from blooms in two Australian lakes

Escherichia coli has long been used as an indicator organism for water quality assessment. Recently there has been an accumulation of evidence that suggests some strains of this organism are able to proliferate in the environment, a characteristic that would detract from its utility as an indicator of faecal pollution. Phenotypic and genotypic characterization of E. coli isolated from blooms in two Australian lakes, separated by a distance of approximately 200 km, identified that the blooms were dominated by three E. coli strains. A major phenotypic similarity among the three bloom strains was the presence of a group 1 capsule. Genetic characterization of a conserved region of the cps gene cluster, which encodes group 1 capsules, identified a high degree of genetic variation within the bloom isolates. This differs from previously described encapsulated E. coli strains which are highly conserved at the cps locus. The phenotypic or genotypic profiles of the bloom strains were not identified in 435 E. coli strains isolated from vertebrates. The occurrence of these encapsulated strains suggests that some E. coli have evolved a free-living lifestyle and do not require a host in order to proliferate. The presence of the same three strains in bloom events in different geographical regions of a temperate climate, and at different times, indicates that free-living E. coli strains are able to persist in these water reservoirs. This study provides further evidence of circumstances where caution is required in using E. coli as an indicator organism for water quality.