The effect of anti-foam agents on the ultrafiltration of a protease solution

Polydimethylsiloxane and polypropylene glycol-based anti-foam agents adversely influence the ultrafiltration rate of a protease solution with polysulfon membranes. Four propietary agents have been compared, of which Rhodosil 426 R (ex Rhone Poulenc, France), an emulsion of polydimethylsiloxane, proved to have the least influence. With this agent, the relative filtration flux of a protease solution decreased by a factor of two for concentrations of anti-foam agent higher than 0.25 cm³/dm³. A simple, quasisteady-state model developed on the basis of data obtained from total recycle experiments with this anti-foam agent, well predicted the temporal variation of protease concentration during batch ultrafiltration experiments with and without Rhodosil 426 R.List of Symbols A _uf m² total membrane area - C _af dm³/m³ concentration of anti-foam agent - C _af,0 dm³/m³ initial concentration of anti-foam agent in the feed solution - C _e kg/m³ protease powder concentration - C _e,0 kg/m³ initial protease powder concentration in the feed solution - J m³/s ultrafiltration rate - J _w m³/m²s water flow for a clean membrane under processing conditions - R _af rejection coefficient for anti-foam agent - R _e rejection coefficient for protein - RF % relative filtration rate - t s filtration time - V m³ concentrate volume - V ₀ m³ volume to be concentrated - V _t m³ end volume     

STORAGE AND GERMINATION OF CHARA OOSPORES

Germination tests were conducted on 39 collections of Chara oospores stored under 4 different conditions for periods of approximately 4 yr. In general, storage of dried oospores at low temperatures (3 C) provided the most satisfactory means for long-term preservation of viable disseminules. Oospore germination zuas higher in light than in darkness. Effects of temperature and substrate upon germination were explored briefly.     

Oceanographic features and limited dispersal shape the population genetic structure of the vase sponge Ircinia campana in the Greater Caribbean

Understanding population genetic structure can help us to infer dispersal patterns, predict population resilience and design effective management strategies. For sessile species with limited dispersal, this is especially pertinent because genetic diversity and connectivity are key aspects of their resilience to environmental stressors. Here, we describe the population structure of Ircinia campana, a common Caribbean sponge subject to mass mortalities and disease. Microsatellites were used to genotype 440 individuals from 19 sites throughout the Greater Caribbean. We found strong genetic structure across the region, and significant isolation by distance across the Lesser Antilles, highlighting the influence of limited larval dispersal. We also observed spatial genetic structure patterns congruent with oceanography. This includes evidence of connectivity between sponges in the Florida Keys and the southeast coast of the United States (>700 km away) where the oceanographic environment is dominated by the strong Florida Current. Conversely, the population in southern Belize was strongly differentiated from all other sites, consistent with the presence of dispersal-limiting oceanographic features, including the Gulf of Honduras gyre. At smaller spatial scales (<100 km), sites showed heterogeneous patterns of low-level but significant genetic differentiation (chaotic genetic patchiness), indicative of temporal variability in recruitment or local selective pressures. Genetic diversity was similar across sites, but there was evidence of a genetic bottleneck at one site in Florida where past mass mortalities have occurred. These findings underscore the relationship between regional oceanography and weak larval dispersal in explaining population genetic patterns, and could inform conservation management of the species.Subject terms: Genetic variation, Ecology     

Comparative analysis of the effect of endogenous antibiotic defensin NP-1 and aminoglycoside antibiotic gentamicin on synaptic transmission in receptors of the frog vestibular apparatus

The effect of human and rabbit neutrophilic defensins NP-1 and amonoglycoside antibiotic gentamicin on the synaptic transmission in the afferent synapse of isolated vestibular apparatus of the frog has been comparatively studied. Both defensins proved active in the concentration range of 0.0001 to 1 nM and efficiently decreased the impulse frequency in the afferent nerve fibers in a concentration-dependent manner. No significant differences in the efficiency of rabbit and human defensin NP-1 have been revealed in these experiments. Gentamicin also had an inhibitory effect on the afferent discharge in the concentration range of 10–500 μM (0.5–25 mg/kg). The inhibitory effect of gentamicin on the impulse activity of the vestibular nerve was observed at therapeutic doses. The excitatory effect of the putative neurotransmitter L-glutamate was considerably inhibited by defensin NP-1. These findings suggest that the mechanism of defensin action involves a modification of the synaptic transmission in the hair cell receptor and modulation of the effect of L-glutamate.     

Hemodynamic component in cerebral compensatory processes following unilateral exclusion of the somatosensory cortex]

In experiments on anesthetised and awake cats the dynamics of the cerebral blood flow was studied by the thermoelectric method in one hemisphere in experimental lesion of the somatosensory zone of the opposite one. Temporary exclusion of the cortical area by cold produced evident hemodynamic changes, i. e. a two-phase vasoreaction and an initial blood flow decrease followed by a prolonged increase of blood supply, in the other hemisphere. Analogous vasoreactions were seen on unilateral extirpation of the cortical layer of the somatosensory zone, as well. Such vasoreactions indicate enhanced activity of the cortical structures in the intact hemisphere and may be considered as a compensatory reaction to the local lesion of certain cortical areas.     

Age-related changes to adipose tissue and peripheral neuropathy in genetically diverse HET3 mice differ by sex and are not mitigated by rapamycin longevity treatment

Neural communication between the brain and adipose tissues regulates energy expenditure and metabolism through modulation of adipose tissue functions. We have recently demonstrated that under pathophysiological conditions (obesity, diabetes, and aging), total subcutaneous white adipose tissue (scWAT) innervation is decreased (‘adipose neuropathy’). With advanced age in the C57BL/6J mouse, small fiber peripheral nerve endings in adipose tissue die back, resulting in reduced contact with adipose-resident blood vessels and other cells. This vascular neuropathy and parenchymal neuropathy together likely pose a physiological challenge for tissue function. In the current work, we used the genetically diverse HET3 mouse model to investigate the incidence of peripheral neuropathy and adipose tissue dysregulation across several ages in both male and female mice. We also investigated the anti-aging treatment rapamycin, an mTOR inhibitor, as a means to prevent or reduce adipose neuropathy. We found that HET3 mice displayed a reduced neuropathy phenotype compared to inbred C56BL/6 J mice, indicating genetic contributions to this aging phenotype. Compared to female HET3 mice, male HET3 mice had worse neuropathic phenotypes by 62 weeks of age. Female HET3 mice appeared to have increased protection from neuropathy until advanced age (126 weeks), after reproductive senescence. We found that rapamycin overall had little impact on neuropathy measures, and actually worsened adipose tissue inflammation and fibrosis. Despite its success as a longevity treatment in mice, higher doses and longer delivery paradigms for rapamycin may lead to a disconnect between life span and beneficial health outcomes.