Developmental change and sexual difference in synaptic modulation produced by oxytocin in rat substantia gelatinosa neurons

We have previously reported that oxytocin produces an inward current at a holding potential of ?70 mV without a change in glutamatergic excitatory transmission in adult male rat spinal lamina II (substantia gelatinosa; SG) neurons that play a pivotal role in regulating nociceptive transmission. Oxytocin also enhanced GABAergic and glycinergic spontaneous inhibitory transmissions in a manner sensitive to a voltage-gated Na⁺-channel blocker tetrodotoxin. These actions were mediated by oxytocin-receptor activation. Such a result was different from that obtained by other investigators in young male rat superficial dorsal horn neurons in which an oxytocin-receptor agonist enhanced glutamatergic and GABAergic but not glycinergic spontaneous transmissions. In order to know a developmental change and also sexual difference in the actions of oxytocin, we examined its effect on spontaneous synaptic transmission in adult female and young male rat SG neurons by using the whole-cell patch-clamp technique in spinal cord slices. In adult female rats, oxytocin produced an inward current at ?70 mV without a change in excitatory transmission. GABAergic and glycinergic transmissions were enhanced by oxytocin, the duration of which enhancement was much shorter than in adult male rats. In young (11–21 postnatal days) male rats, oxytocin produced not only an inward but also outward current at ?70 mV, and presynaptically inhibited or facilitated excitatory transmission, depending on the neurons tested; both GABAergic and glycinergic transmissions were enhanced by oxytocin. The inhibitory transmission enhancements in adult female and young male rats were sensitive to tetrodotoxin. Although the data may not be enough to be estimated, it is suggested that synaptic modulation by oxytocin in SG neurons, i.e., cellular mechanism for its antinociceptive action, exhibits a developmental change and sexual difference.     

Evaluation of a two-stage in vitro technique for estimating digestibility of equine feeds using horse faeces as the source of microbial inoculum

To develop a two-stage in vitro technique that simulates both pre-caecal and hind gut digestion processes, four enzymatic pre-digestion treatments by pepsin and α-amylase (ET0 = control, ET1 = 2 h pepsin + 2 h amylase, ET2 = 2 h pepsin + 4 h amylase, ET3 = 8 h pepsin + 16 h amylase) were tested on oat hay (OH), barley grain (BG) and soybean meal (SBM). Investigated parameters were enzymatic organic matter digestibility (OMDe), and gas production (G48h, G72h) and OM digestibility (OMD) using horse faeces as a source of microbial inoculum.Enzymatic pre-digestion treatments affected (P<0.05) investigated parameters and their ranking differed among feeds. Only OMD of BG and SBM were higher after the pre-digestion treatment. OMD prior to (ET0) and after ET3 application were, successively, 0.357 versus 0.351 (OH), 0.71 versus 0.79 (BG) and 0.70 versus 0.78 (SBM). Net gas production overestimated fermentation potential of non-pre-digested feeds. G72h (ml/g DM) prior to (ET0) and after ET3 application were, successively, 80.3 versus 58.0 (OH), 151.7 versus 30.4 (BG) and 110.6 versus 37.7 (SBM).It was concluded that the enzymatic pre-digestion treatments effects varied among tested feeds, and that the suggested procedure be extended and validated with a large array of feeds of known digestibility values.     

Nutrient digestibility in Atlantic salmon and broiler chickens related to viscosity and non-starch polysaccharide content in different soyabean products

Total tract digestibility in Atlantic salmon and ileal digestibility in chicken were assessed from diets with different soyabean products (hulled, toasted, extracted, SBM; reduced oligosaccharide content, ROM; ethanol-extracted protein concentrate, SPC; isolated protein, ISP). The concentration of dietary fibre was highest in SBM and ROM, while it was low in ISP. In vitro viscosity was also higher in SBM than in the other soyabean products. The diets for the salmon and chickens were based on the same feed ingredients, with the exception that fish meal provided half the crude protein in the salmon diets. For each species, the diets were isonitrogenous, contained similar amounts of fat (fish oil), and were balanced with dextrin, thus substituting soyabean non-starch polysaccharides (NSP) and other non-proteinous components by dextrin.In the salmon, total tract digestibility of nitrogen and dry matter were lower (p < 0.05) with the SBM and ROM diets than with the ISP diet. In the chickens, ileal digestibility of dry matter differed among all treatments (p < 0.05). Digestibility of nitrogen, starch, phosphorus and calcium in the chickens was lower (p < 0.05) with the SBM diet than with the ISP and SPC diets, and fat digestibility was lower (p < 0.05) with the SBM and ROM diets than with the SPC diet. Also, the SBM diet gave lower (p < 0.05) digestibility of nitrogen, phosphorus and calcium than the ROM diet, while the ROM diets gave lower (p < 0.05) digestibilities of nitrogen, fat and starch than the ISP and SPC diets. Intestinal viscosity was higher (p < 0.05) and cholesterol content in the blood was lower (p < 0.05) for the chickens fed the SBM-based diet than those fed the other diets. There was a similar response to the different soy products in salmon and chickens with regard to digestibility of nitrogen and fat (p < 0.05). The negative effects of soyabean meals with a low protein content could indicate antinutritive effects of NSP fractions in soyabean meal, as indicated by the elevated viscosity and the decrease in blood cholesterol content.     

Effects of considering the rate of comminution of particles and microbial contamination on accuracy of in situ studies of feed protein degradability in ruminants

Ruminal degradation of dry matter (DM) and crude protein (CP) in samples of soybean meal (SBM), barley grain (BG) and lucerne hay (LH) were measured by an in situ ruminal technique considering either only the outflow rate of particles from the rumen (k_p) or, both k_p and rate of particle comminution (k_c). The effect of correction for the microbial contamination using an ¹⁵N technique was also determined for LH. Degradation and transit studies were completed on three wethers cannulated in the rumen and duodenum and fed a mixed diet of LH and concentrate (2:1 on DM), at an intake level of 50 g DM/kg BW^0.75. Transit studies of concentrates and forages were completed with SBM and LH samples marked with Yb and Eu, respectively. Mean values of k_c were higher in SBM than in LH (0.357 versus 0.204 h, P < 0.05). The same trend was observed for k_p (0.0587 versus 0.0452/h; P < 0.1). Apparent estimates of the proportion of rumen undegraded CP obtained using both rates were 0.884, 0.745 and 0.825 of those obtained using only k_p (0.535, 0.247 and 0.303 for SBM, BG and LH, respectively). Differences occurred for SBM and LH (P < 0.01) and for BG (P < 0.05). The pattern of microbial contamination of LH, expressed as a proportion of residual DM or CP, fitted exponential curves with asymptotic values of 0.076 and 0.586, respectively. Correction for microbial contamination reduced (P < 0.05) estimates of undegraded CP from 0.303 to 0.238, which was further reduced to 0.178 (P < 0.01) when the effect of k_c was also considered.     

Involvement of nigral oxytocin in locomotor activity: A behavioral,immunohistochemical and lesion study in male rats

Oxytocin is involved in the control of different behaviors, from sexual behavior and food consumption to empathy, social and affective behaviors. An imbalance of central oxytocinergic neurotransmission has been also associated with different mental pathologies, from depression, anxiety and anorexia/bulimia to schizophrenia, autism and drug dependence. This study shows that oxytocin may also play a role in the control of locomotor activity. Accordingly, intraperitoneal oxytocin (0.5–2000 μg/kg) reduced locomotor activity of adult male rats. This effect was abolished by d(CH₂)₅Tyr(Me)²-Orn⁸-vasotocin, an oxytocin receptor antagonist, given into the lateral ventricles at the dose of 2 μg/rat, which was ineffective on locomotor activity. Oxytocin (50–200 ng/site) also reduced and d(CH₂)₅Tyr(Me)²-Orn⁸-vasotocin (2 μg/site) increased locomotor activity when injected bilaterally into the substantia nigra, a key area in the control of locomotor activity. Conversely, the destruction of nigral neurons bearing oxytocin receptors by the recently characterized neurotoxin oxytocin-saporin injected into the substantia nigra, increased basal locomotor activity. Since oxytocin-saporin injected into the substantia nigra caused a marked reduction of neurons immunoreactive for tyrosine hydroxylase (e.g., nigrostriatal dopaminergic neurons) and for vesicular glutamate transporters VGluT1, VGluT2 and VGluT3 (e.g., glutamatergic neurons), but not for glutamic acid decarboxylase (e.g., GABAergic neurons), together these findings suggest that oxytocin influences locomotor activity by acting on receptors localized presynaptically in nigral glutamatergic nerve terminals (which control the activity of nigral GABAergic efferent neurons projecting to brain stem nuclei controlling locomotor activity), rather than on receptors localized in the cell bodies/dendrites of nigrostriatal dopaminergic neurons.     

Effects of non-enzymatic browning reaction intensity on in vitro ruminal protein degradation and intestinal protein digestion of soybean and cottonseed meals

The effects of non-enzymatic browning reactions on in vitro ruminal gas production and in vitro ruminal and intestinal crude protein (CP) digestibilities of soybean (SBM) and cottonseed (CSM) meals were investigated. Non-enzymatically browned SBM and CSM samples were prepared using two xylose levels (10 or 30 g/kg dry matter), two heating lengths (30 or 60 min) and two heating temperatures (120 or 150 °C) for a total of one untreated (commercially solvent-extracted, Control) and eight treated samples for each protein source. The control SBM had higher (P<0.001) in vitro ruminal CP degradability values than the treated samples. Intestinal protein digestibility and total-tract CP digestibility of CSM and SBM were affected by the treatment (P<0.01). The results of the study indicate that not only ruminal CP degradability is reduced but also intestinal and total-tract CP digestibilities may be lowered depending on protein source and intensity of the non-enzymatic browning reaction.     

Dietary inclusion of raw faba bean instead of soybean meal and enzyme supplementation in laying hens: Effect on performance and egg quality

An experiment was conducted with 160 Hisex Brown laying hens to evaluate the effect of different inclusion levels of faba bean (FB) and enzyme supplementation on productive performance and egg quality parameters. The experimental diets consisted of five levels of FB: 0% (control), 25%, 50%, 75% and 100%, substituting soybean meal (SBM), and two levels of enzyme supplementation (0 or 250 mg/kg). Each dietary treatment was assigned to four replicate groups and the experiment lasted 22 weeks. A positive relationship (P < 0.05) was found between FB inclusion and body weight (BW) change of hens when compared to those of the control treatment. Enzyme supplementation significantly affected the final hens’ BW. Feed consumption (FC) of hens was statistically increased with increasing FB level up to 50%. Supplementing dietary enzyme mixture at 250 mg/kg led to improvement in FC at all studied ages (P < 0.05). Inclusion of 25% or 50% FB in diets had no adverse effects on feed conversion ratio (FCR) compared to the higher FB inclusion levels (75% or 100%). Egg weight (EW), egg number (EN) and egg mass (EM) were significantly (P < 0.05) influenced by FB inclusion in diet during the entire experimental periods, except for EN and EM at 20–24 weeks of age. Egg productive parameters were not influenced by enzyme mixture supplementation (P > 0.05). The main effect of FB levels replacing for SBM affected (P < 0.05) yolk and shell percentages, yolk index, yolk to albumen ratio, shell thickness and egg shape index. It can be concluded that FB and enzyme supplementation could be included in hens diet at less than 50% instead of SBM to support egg productive performance, however higher raw FB levels negatively affected egg production indices and quality.     

Auxin-cytokinin synergism in vitro for producing genetically stable plants of Ruta graveolens using shoot tip meristems

An efficient micropropagation protocol was developed for Ruta graveolens Linn. using shoot tip meristems derived from a 4-month-old field grown plant. In vitro shoot regeneration and proliferation was accomplished on Murashige and Skoogs (MS) semi-solid medium in addition to different doses of cytokinins viz.6- benzyl adenine (BA), Kinetin (Kn) or 2-isopetynyl adenine (2iP), singly or in combination with auxins viz. indole-3-acetic acid (IAA), indole-3-butyric acid (IBA) or α-naphthalene acetic acid (NAA). Highest regeneration frequency (27.6%) was obtained on (MS) medium composed of BA (10 µM) with maximum number (9.4) of shoots and 4.3 cm shoot length after 4 weeks of incubation. Among various combinations tried best regeneration frequency (71%) of multiple shoot formation with highest number (12.6) of shoots per shoot tip explants were achieved in MS medium augmented with a combination BA (10.0 µM) and NAA (2.5 µM) after 4 weeks of incubation. The optimum frequency (97%) of rhizogenesis was achieved on half-strength MS medium having 0.5 µM IBA after 4 weeks of incubation. Tissue culture raised plantlets with 5–7 fully opened leaves with healthy root system were successfully acclimatized off in Soilrite? with 80% survival rate followed by transportation to normal soil under natural light. Genetic stability among in vitro raised progeny was evaluated by ISSR and RAPD markers. The entire banding pattern revealed from in vitro regenerated plants was monomorphic to the donor. The present protocol provides an alternative option for commercial propagation and fruitful setting up of genetically uniform progeny for sustainable utilization and germplasm preservation.     

Epidermal growth factor, basic fibroblast growth factor and platelet-derived growth factor-bb can substitute for fetal bovine serum and compete with human platelet-rich plasma in the ex vivo expansion of mesenchymal stromal cells derived from adipose tissue

Background aimsHuman mesenchymal stromal cells (MSC) are multipotent cells possessing self-renewal capacity, long-term viability and multilineage potential. We analyzed the effect of four different medium supplements on the expansion and differentiation of adipose tissue-derived MSC (ADSC) in order to avoid the use of xenogeneic serum.MethodsWe compared fetal bovine serum (FBS) with 10% human platelet-rich plasma (hPRP), 3% human platelet-poor plasma (hPPP) and with a cytokine cocktail composed of epidermal growth factor (EGF), basic fibroblast growth factor (bFGF) and platelet-derived growth factor-bb (PDGFbb) added to 3% hPPP. This mixture was developed testing EGF, bFGF, granulocyte–colony-stimulating factor (G-CSF), hepatocyte growth factor (HGF), insulin-like growth factor (IGF-I), PDGFbb and transforming growth factor (TGF)-β1 added alone or in combination with hPPP.ResultsOur data demonstrate that the addition of EGF, bFGF and PDGFbb, in a medium supplemented with hPPP, obtainable from 150–200 mL whole autologous blood, supports ADSC expansion better than FBS, as confirmed by cumulative population doublings (cPD; 15.0 ± 0.5 versus 9.4 ± 2.8). The addition of human platelet-rich plasma (hPRP) further improved ADSC proliferation (cPD 20.0 ± 1.2), but the achievement of hPRP presented a major drawback, requiring 1000–1200 mL autologous or donor whole blood. The medium supplements did not influence ADSC phenotype: they expressed CD105, CD90 and CD44 lacking hematopoietic antigens. The exposure to the proposed cocktail or to hPRP increased adipogenic and osteogenic differentiation.ConclusionsThe addition of EGF, bFGF and PDGFbb to hPPP could ensure a sufficient number of ADSC for clinical applications, avoiding the use of animal serum and representing a novel approach in regenerative medicine.     

In vitro cultures of Silybum marianum and silymarin accumulation

In this study, a protocol for initiation of callus and shoot cultures from leaves and shoot tips explants of different silybium genotypes collected from different locations in Egypt was established. Callus cultures were initiated from leaves explants and exposed to different concentrations of the precursor (coniferyl alcohol). Shoot cultures were initiated from shoot tips explants. Moreover, the produced plants of the different Silybium shoots as well as intact plants were subjected to protein screening using SDS–PAGE analysis.Results obtained revealed that the optimum medium for growth and maintenance of friable callus was MS medium supplemented with 0.25 mg L⁻¹ 2,4-Dichlorophenoxy acetic acid (2,4-D) + 0.25 mg L⁻¹ Kinetin (Kin). The best medium for proliferation of high number of shoots was MS-medium with 0.25 mg L⁻¹ each of Benzyl Adinine (BA) and Naphthalene Acetic Acid (NAA). Coniferyl alcohol in concentration of 30 μM caused an increase in accumulation of silymarin contents in most callus cultures. SDS–PAGE of different Silybium shoots revealed that the protein profiles of 100% of in vitro produced plantlets similar to their control.     

Long-term stability of tensiomyography measured under different muscle conditions

Tensiomyography (TMG) is a technique utilised to measure mechanical and contractile properties of skeletal muscle. Aim of this study was to assess long-term stability of TMG across a variety of muscle conditions. Gastrocnemius Medialis of 21 healthy males was measured using TMG in rested conditions, after a warm-up, after a maximal voluntary contraction and after a fatigue protocol. Participants were re-tested on a second occasion 4 weeks apart. Among the parameters examined, Contraction Time, Sustain Time and Delay time exhibited a good level of absolute reliability (CV = 3.8–9.4%) and poor to excellent level of relative reliability (ICC = 0.56–0.92). On the other hand, relative reliability was good to excellent for muscle Displacement (ICC = 0.86–0.96), whereas its level of absolute reliability was questionable (CV = 8.0–14.8%). Minimum detectable change was less than 20% in most conditions for the aforementioned parameters. Half-relaxation Time yielded overall insufficient reliability. In general, the level of reliability tended to increase after the maximal voluntary contraction and the fatigue protocol were administered, probably because of more controlled conditions preceding the measurement. Information about the long-term stability of TMG across different muscle conditions is essential when intervention studies are undertaken with an exercising population, particularly athletes.     

Hair snaring and molecular genetic identification for reconstructing the spatial structure of Eurasian lynx populations

Non-invasive genetic sampling (NGS) is being increasingly applied in wildlife monitoring and population genetic research. This study was designed to evaluate the use of NGS for reconstructing the spatial structure of populations of large felids. We developed a procedure for reliably genotyping individuals of Eurasian lynx (Lynx lynx) from samples obtained through a hair-trapping scheme based on a network of lynx scent-marking sites. The spatial locations of the identified genotypes were matched with the home ranges distribution of radio-tracked individuals, thus cross-checking the accuracy of the two methods. We analyzed DNA extracted from 170 hair samples and 11 blood samples from live-trapped lynx collected in 2004–2009 in the Bia?owie?a Primeval Forest, Poland. We obtained PCR products in 96 (67%) hair samples; 82 (85%) of them were reliably genotyped at 12 autosomal microsatellite loci following a multiple-tubes protocol and stringent quality-controls of the data set. The sample included 29 distinct genotypes; 18 were found only in hair samples, five were determined only in live-trapped animals, and six in both hair and blood samples. Based on linkage disequilibrium we estimated an effective population size N_e = 20.3 (90% CI = 15–28). The total population size estimated with Capwire was N_c = 32 (95% CI = 25–37) in close agreement with the observed number of genotypes. The genotypes obtained from hair samples were re-sampled on average 3.9 times and 50% of them were recorded for more than one year. The spatial distribution of six hair-genotypes was consistent with their home ranges obtained by radio-tracking in the same period. The distribution ranges of hair-trapped genotypes overlapped on average in 86.4% (mode 100%) with home ranges of the corresponding individuals. Hair-trapping and molecular identification is a reliable method for reconstructing the spatial organization of lynx population. It is likely to be also efficiently used in other rare and endangered species of felids in combination with data from other monitoring techniques, such as radio- and snow-tracking and photo-trapping.     

Anthropometric measurements by ethnicity in Colombia, 1965–1990

We analyzed the evolution of height in Colombia of cohorts born in the period 1965–1990 by ethnic groups. We found that Afro-Colombian men and women were the tallest: 6 cm taller than indigenous people and 2 cm taller than the rest of the population. We also found that the height gap between Afro-Colombians and others decreased during the period under study by 0.7 cm for both men and women. While improvements were noticeable among the Afro-Colombians and those who chose not to be classified by ethnicity, in the case of the indigenous population only female cohorts registered an average-height increase of 1.5 cm. Moreover, we found that indigenous Colombians were more likely than other ethnic groups to experience an increase in biological well-being as a consequence of an improvement in their socio-economic status, thereby reducing the average-stature gap between them and the rest of the population by 2.1 and 3.6 cm for men and women, respectively.     

Preparation and characterization of mixed-mode magnetic adsorbent with p-amino-benzamidine ligand: Operated in a magnetically stabilized fluidized bed reactor for purification of trypsin from bovine pancreas

The magnetic beads were synthesized using glycidylmethacrylate (GMA) and methylmethacrylate (MMA) monomers. A multimodal ligand (i.e., p-amino-benzamidine) was covalently immobilized onto magnetic beads after glutaraldehyde activation, and consequently used for purification of the trypsin from bovine pancreas. The p-amino-benzamidine ligand immobilized magnetic beads were characterized by FTIR, VSM, SEM, and analytical methods. Trypsin adsorption experiments were investigated under different experimental conditions (i.e., medium pH, initial trypsin concentration, temperature, and ionic strength) in a batch system. Maximum trypsin adsorption capacity was found to be 75.9 ± 2.6 mg/g beads. Adsorbed trypsin was eluted by using (0.1 M acetate buffer, pH 3.0) with a 97% recovery. The purification factor of trypsin from crude pancreas extract was 8.7 folds. The purity of the eluted trypsin from p-amino-benzamidine functionalized magnetic beads was determined as 86% by HPLC. The method developed in this report was successfully applied for purification of the trypsin from crude pancreas extract in a magnetically stabilized fluidized bed reactor.     

Concurrent purification and antioxidant activity of phycobiliproteins from Lyngbya sp. A09DM: An antioxidant and anti-aging potential of phycoerythrin in Caenorhabditis elegans

The present study probes into the purification of phycobiliproteins, and characterization of their in vitro anti-oxidant activity. Moreover, the study also demonstrates the use of antioxidant virtue of phycoerythrin in moderating the phenomenon of aging in Caenorhabditis elegans. Phycoerythrin, phycocyanin and allophycocyanin were purified successfully from Lyngbya sp. A09DM by ammonium sulfate fractionation appended with Triton X-100 intercession. The success of protocol was examined by a series of biochemical characterization like SDS-PAGE, native-PAGE, UV–visible spectroscopy and fluorescence spectroscopy ensuring purity, integrity and functionality of purified phycoerythrin, phycocyanin and allophycocyanin. Purified phycobiliproteins were evaluated for antioxidant and metal ion chelating activity by various in vitro antioxidant assay systems. Results showed significant and dose-dependent antioxidant as well as metal chelating potential of all phycobiliproteins in decreasing order of phycoerythrin > phycocyanin > allophycocyanin. Expansion in lifespan and improvement in pharyngeal pumping of C. elegans were noticed upon pre-treatment with phycoerythrin (100 μg ml⁻¹). Moreover, phycoerythrin mediated increase in worm survival under oxidative stress revealed that the life expansion effect of phycoerythrin on nematode is in part by an action of its antioxidant virtue. These results collectively added up evidence in favor of the ‘free-radical theory of aging’. The present report, for the first time, describes antioxidant potential of phycoerythrin and its use in extending life-span of C. elegans.     

Peas (Pisum sativum L.) as an alternative protein source in lamb diets: growth performances,and carcass and meat quality

Thirty weaned Barbaresca lambs were divided into three groups and fed diets that differed in their protein supplement source; the main protein source was soybean meal in SBM diet treatment, totally or partially replaced by peas in P39 and P18 diet treatments, respectively. Soybean meal and peas were present in the diets in the following proportions (on as fed basis): 16:0% (SBM), 0:39% (P39), 9:18% (P18).The diets were of different crude protein content: higher in SBM diet (16.96% DM) than in P39 (14.27% DM) and P18 (15.37% DM). Soluble protein was higher in P39 diet than in the other treatments (36.2, 27.4 and 23.14% CP in P39, P18 and SBM treatments, respectively) while the B₂-protein fraction was lower. The NDF-bound nitrogen was 17.36, 16.87 and 15.06% of crude protein in P39, P18 and SBM diet, respectively. The NDF content was similar among the diets. Growth and slaughter performances were similar among groups (250 g per day versus 219 and 218 g per day respectively in P18, P39 and SBM groups). Carcass fatness was comparable among treatments. Meat pH, colour parameters and cooking losses were comparable among groups. Drip losses were significantly higher (P<0.001) in meat from P39 and P18 than from SBM group. In the present trial, the replacement of soybean meal with peas did not significantly affect growth and slaughter performances and preserved meat quality.     

Reversible lysozyme immobilization onto N,N′-bis-(3-(4-morpholino)-propyl)-3,4,9,10-perylenetetracarboxylic acid dimide (MPPDI) attached polymeric nanospheres

Novel hydrophobic nanospheres with an average size of 200 nm utilizing N,N′-bis-(3-(4-morpholino)-propyl)-3,4,9,10-perylenetetracarboxylic acid dimide (MPPDI) as a monomer were prepared by surfactant free emulsion polymerization of 2-hydroxyethyl methacrylate (HEMA) and MPPDI conducted in an aqueous dispersion medium. The nanospheres were used for the adsorption of lysozyme. The system parameters, such as effect of the adsorption conditions (i.e. enzyme concentration, medium pH, and temperature) and the reusability of the support were studied. Specific surface area of the nonporous nanospheres was found 664 m²/g. Poly(HEMA–MPPDI) nanospheres were characterized by Fourier transform infrared spectroscopy (FT-IR), elemental analysis and scanning electron microscopy (SEM). Then, poly(HEMA–MPPDI) nanospheres were used in the adsorption of lysozyme in batch system. Using an optimized adsorption protocol, 400 mg lysozyme/g nanosphere loading capacity was obtained. The adsorption phenomena appeared to follow a typical Langmuir isotherm. Lysozyme could be repeatedly adsorbed and desorbed with poly(HEMA–MPPDI) nanospheres without noticeable loss in the adsorption capacity.     

Newly developed medium and strategy for bacterial cellulose production

Bacterial cellulose (BC) has unique properties, such as high crystallinity, a high degree of polymerisation, high tensile strength and high purity, compared with native cellulose. In this study, a previously determined BC production medium was improved in static culture, and the production cost was evaluated and compared with molasses and with other defined media, such as Hestrin–Schramm, Zhou, Yamanaka and Park, using Gluconacetobacter xylinus. In addition to this analysis, because the surface area/volume ratio is an important parameter in static culture, different surface area/volume ratios were analysed in the range of 0.2–1.46. The defined medium (M1A05P5) and culture type contained glucose (10 g/L), yeast extract (10 g/L), peptone (7 g/L), acetic acid (1.5 ml/L), and ethanol (5 ml/L), and the pH was adjusted to 5.0 in static culture. The highest productivity was observed in the M1A05P5 medium that was 5-fold higher than either molasses or Park's medium. Although the molasses medium was proposed as a cost-effective medium, the production price of BC was the lowest in the M1A05P5 medium. Therefore, the newly developed medium and strategy were highly promising candidates for the industrial-scale production of BC.     

Growth limitation of Lemna minor due to high plant density

The effect of high population densities on the growth rate of Lemna minor (L.) was studied under laboratory conditions at 23 °C in a medium with sufficient nutrients. At high population densities, we found a non-linear decreasing growth rate with increasing L. minor density. Above a L. minor biomass of ca. 180 g dry weight (DW) m⁻², the net growth rate became negative. At a density of 9 g DW m⁻², a maximum relative growth rate of ca. 0.3 d⁻¹ was found. At very low densities (<9 g m⁻²), we observed an inverse density dependence (or Allee effect). Probably, this lower growth rate was due to lower local temperatures within such partly covered L. minor decks. On the basis of these experimental results and literature data, a simple model was created. To test the model, the density of duckweed in three different Dutch ditches was monitored for 9 weeks in spring. Within this period, full coverage of the ditches by duckweed was reached. The maximum density increased with rising air temperature. The model described the field data well, suggesting that crowding is an important factor in limitation of duckweed growth.     

Evaluation of adsorbents for separation and purification of paclitaxel from plant cell cultures

In this study, we evaluated the efficiency of different adsorbents for the removal of plant-derived impurities during the pre-purification of paclitaxel from plant cell cultures. Using the synthetic adsorbents sylopute and active clay and their major components SiO₂ and MgO, we performed adsorbent treatment and analyzed the paclitaxel precipitates recovered from hexane precipitation. When SiO₂ was used, the highest purity (～58.1%) and yield (～91.5%) of paclitaxel were obtained. We also determined differences in the effectiveness of the adsorbent treatment according to changes in the surface area, pore volume and pore diameter of SiO₂. Adsorbent treatment was more effective when pore diameter was larger (silica I [2.19 nm] < silica II [4.92 nm] < silica III [9.07 nm]). The highest purity (～74.3%) and yield (～92.9%) of paclitaxel were obtained when silica III was used in the adsorbent treatment. Pore diameter had a greater effect on the removal of plant-derived impurities during the pre-purification of paclitaxel compared with surface area and pore volume. This result could be confirmed by HPLC analysis of the absorbent after treatment and TGA of the organic substances that were bonded to the adsorbent.