Alternative pathways in the life history of Gracilaria gracilis (Gracilariales, Rhodophyta) from north-eastern Sicily (Italy)

The reproductive phenology of Gracilaria gracilis has been followed closely in a brackish water lake in Sicily. The life history of this red alga deviated from the typical Polysiphonia-type cycle and was characterized by the predominance of the tetrasporophytic phase over gametophytes, in situ development of germinated gametophytes and the presence of sterile pleustophytic thalli. Release of spherical agglomerates of cells produced by young tetrasporophytes was observed as well. Their ability to germinate forming new thalli appears to represent an alternative reproductive strategy of this organism. The population structure appears to reflect a predominance of the diploid phase except during the warmer summer season when only vegetative juveniles were found in the lake. Release and early stages of development of carpospores and tetraspores were critically observed in culture. A Dumontia type pattern of germination was observed for both types of spores, showing an erect thallus arising from a multicellular basal disk. Compared to tetraspores, carpospores are less readily released resulting in a subsequent delay in the development of new gametophytes.     

Collection,ex situ conservation and characterization of mangaba (Hancornia speciose Gomes) germplasm in coastal lowland of Northeastern Brazil

Genetic Resources and Crop Evolution - This study aimed to evaluate the Mangaba Genebank of Embrapa Tabuleiros Costeiros, Brazil, since its implementation in 2006 and characterize the accessions in...     

Decomposition of cattle manure and colonization by macroinvertebrates in sediment of a wetland of the Middle Paraná River

Purpose

The study was carried out in a wetland of the Middle Paraná River system, Argentina, in order to evaluate the processes associated with the decomposition of manure, which includes changes in chemical composition, nutrient release of manure, and colonization of invertebrates. We also compared the invertebrate assemblage that colonized manure with that present in the benthos of the wetland.

Materials and methods

Nylon bags were filled with fresh cattle manure and anchored to the littoral zone of the wetland. Six bags were collected after 1, 2, 6, 14, 21, 28, 33, 55, and 79 days: three for invertebrate determination and the other three bags for determination of dry mass and chemical analyses. The nutrient content, cellulose, lignin, and total phenolic compounds of manure were determined. In addition, the leachate of manure was collected for nutrient analyses. Samples of the wetland benthic sediment were collected for benthic invertebrate determination and particle size analyses. Spearman rank correlation was used to evaluate the relationship between chemical compounds of manure and breakdown rate. Principal component analysis was used to explore invertebrate assemblage composition of manure and sediment during the experiment.

Results and discussion

Limnodrilus, Dero, and Chironomus were dominant in the manure. Gatherer-collector was the dominant group in the manure, comprising almost 95 % of the total density of invertebrates. Breakdown rate was significantly related with nutrients, cellulose and total phenolics of manure. An ordination plot showed changes in invertebrate assemblages of manure and sediment samples over time.

Conclusions

This study provides new insight on the importance of manure as a substrate for macroinvertebrate colonization. Cattle manure needs to be considered as a potential source of nutrients for aquatic systems and a substrate for invertebrate assemblages.

     

Study of the effect of soy proteins on the acid-induced gelation of casein micelles

The objective of this research was to understand whether addition of soy protein to milk protein affects the properties of acid-induced casein gels. Different samples were prepared by suspending casein micelles pellets in milk serum containing soy proteins or whey proteins as well as mixtures of the two proteins. Glucono-delta-lactone was added, and the changes in apparent size (in diluted systems) as well as the viscoelastic properties of the mixtures were measured. Size exclusion chromatography was also carried out to characterize the soluble phase of the various mixtures before and after heating. Soy protein affected the gelation of the mixtures; however, not to the same extent as whey proteins, which dominated formation of the network in soy-whey-casein systems. It was concluded that, up to a critical ratio of soy/whey proteins, soy proteins can be incorporated in the mix without a significant change in structure of the casein gels.     

Addition of pectin and soy soluble polysaccharide affects the particle size distribution of casein suspensions prepared from acidified skim milk

Pectins are negatively charged polysaccharides employed as stabilizers in acidified milk dispersions, where caseins aggregate because of the low pH and serum separation needs to be prevented. The objective of this research was to study the effect of charge on the stabilizing functionality of the polysaccharide in acid milk drinks. Unstandardized pectins with various charges (as degree of esterification, DE) as well as soybean soluble polysaccharide (SSPS) were tested for their stabilizing behavior as a function of pH and concentration. Skim milk was acidified by glucono-delta-lactone and then homogenized in the presence of polysaccharide at different pH values (in the range from 4.2 to 3.0). Measurements of particle size distribution demonstrated that pectins with a DE of 71.4, 68.6, and 67.4 stabilized milk at pH > 4.0. Pectins with a lower DE (63.9%) needed a higher concentration (0.4%) at the same pH to show a monomodal distribution of particle sizes. Pectins with lower DE (<50%) did not stabilize the dispersions. Although this difference in behavior was attributed mainly to the pectin charge, the efficiency in stabilizing the casein dispersion decreased with decreasing pectin size. For example, the high methoxyl pectin (HMP) with 63.9 DE was smaller in size than the HMPs with a higher charge. Pectins showed a pH-dependent stabilization effect, as at pH < 4.0 the dispersions contained aggregates. When SSPS was used to stabilize acid milk, at pH < 4.0, it showed a better stabilization behavior than HMP. When SSPS and pectin were used in combination, the particle size distribution of the acid milk dispersion was pH-dependent, and results were similar to those for samples containing pectin alone. This suggested that in the mixture, pectin dominated the behavior over SSPS, even when an excess of SSPS was added to the dispersions before homogenization.     

Influence of heating on oil-in-water emulsions prepared with soybean soluble polysaccharide

The effect of heating on the physicochemical properties of emulsions prepared with soybean soluble polysaccharide (SSPS) was investigated. The emulsions were stable after heating at 90 degrees C for up to 30 min. Heating at different pH values or in the presence of CaCl2 (<10 mM) did not affect the stability; however, at higher concentrations of calcium ions, the emulsion particle size increased. Two fractions, a high molecular weight (HMF) and a low molecular weight (LMF) fraction, were separated from the crude SSPS preparation by gel fitration. Emulsions prepared with SSPS/HMF (MW = 310-420 kDa) showed little change in size with heating, while the protein impurities of the SSPS/LMF fraction formed aggregates by heating at pH 7. Analysis of the heat-induced aggregation of the two fractions of SSPS suggested that the changes in SSPS functionality with heating can be attributed to the protein impurities (LMF) present in the SSPS.     

Variation and covariation for Gibberella ear rot resistance and agronomic traits in testcrosses of doubled haploid maize lines

Gibberella ear rot (GER) of maize caused by Fusarium graminearum reduces grain yield and leads to contamination of the grains with deoxynivalenol (DON), a mycotoxin that adversely affects the health of humans and animals. The objectives of this study were to (1) analyze means and genotypic variances for line per se performance (LP) and testcross performance (TP) of doubled haploid (DH) lines for GER severity and DON concentration as well as for some agronomic traits, (2) examine correlations among these traits, (3) validate QTL for resistance detected in previous studies for LP and their effect on TP and (4) investigate the relative efficiency of indirect selection (RE) for LP to improve TP. Testcross progenies of 94 DH lines originating from four flint populations were developed using a susceptible dent tester as pollinator. Artificial inoculations with F. graminearum led to appreciable disease development. Average TP for GER severity and DON concentration were lower than the mean mid-parent values of the tester and DH lines, indicating mid-parent heterosis for resistance. Genotypic variation for resistance was significant for LP and TP. Genotypic correlations between LP and TP were low and resistance QTL for LP had no significant effects on TP. Accordingly, RE for resistance was low, suggesting to allocate resources mostly to the evaluation of testcrosses. Correlations of resistance to GER and DON contamination with grain yield (measured under non-inoculated conditions) were not significant, indicating that selection for resistance and higher grain yield can be carried out simultaneously.     

Seroepidemiological characterization and risk factors associated with seroconversion to Corynebacterium pseudotuberculosis in goats from Northeastern Brazil

Goat breeding in the Northeast region of Brazil plays an important socioeconomic role. However, there are significant losses caused by sanitary deficits and infectious diseases, particularly caseous lymphadenitis (CL). Although CL is considered endemic in Northeastern Brazil, a comprehensive and up-to-date study of this disease in goat herds in this region is necessary. The objective of this study was to determine the farm-level and animal-level seroprevalences for the disease and to identify the possible risk factors that characterize CL in the caprine species of five Northeastern’s states (Ceará, Piauí, Rio Grande do Norte, Paraíba, and Sergipe). A total of 2744 goat serum samples from 230 farms were collected between 2010 and 2012. The diagnosis of Corynebacterium pseudotuberculosis infection was performed using the indirect ELISA technique. Farm-level and animal-level seroprevalences were 87.8% and 30.3%, respectively, suggesting that C. pseudotuberculosis is widespread in goat herds of the Northeast region. The risk factors were as follows: absence of forage silage (odds ratio?=?5.39), not separating animals by sex (odds ratio?=?4.16) or by age (odds ratio?=?6.30), not replacing old goat breeders (odds ratio?=?7.80), and non-treatment of CL lumps prior to spontaneous rupture (odds ratio?=?10.34). This study supports the idea that caseous lymphadenitis is widely disseminated in goats from Northeastern Brazil and based on the risk factor analysis attention should be given to the need to establish adequate control measures, such as incision and early drainage of superficial abscesses, quarantine and elimination of affected animals, periodic inspection of the herd, non-introduction of infected animals, and early disposal of animals with recurrent CL.

     

Immune defense of wild‐caught Norway rats is characterized by increased levels of basal activity but reduced capability to respond to further immune stimulation

Studies of wild animals' immunity often use comparison with laboratory‐raised individuals. Using such an approach, various data were obtained concerning wild Norway rat's immunity. Lower or higher potential of immune system cells to respond to activation stimuli were shown, because of analysis of disparate parameters and/ or small number of analyzed individuals. Inconsistent differences between laboratory and wild rats were shown too, owing to great response variability in wild rats. We hypothesized that wild rats will express more intense immune activity compared to their laboratory counterparts which live in a less demanding environment. To test this, we analyzed the circulating levels of inflammatory cytokine interleukin‐6 (IL‐6), a mediator which has a central role in host immune defense. In addition, we examined the activity of the central immune organ, the spleen, including cell proliferation and production of pro‐inflammatory cytokines interferon‐γ (IFN‐γ) and interleukin‐17 (IL‐17), which are major effectors of cellular adaptive immune response. In order to obtain reasonable insight into the immunity of wild Norway rats, analysis was conducted on a much larger number of individuals compared to other studies. Higher levels of plasma IL‐6, higher spleen mass, cellularity and basal IFN‐γ production concomitantly with lower basal production of anti‐inflammatory cytokine interleukin‐10 (IL‐10) revealed more intense immune activity in the wild compared to laboratory rats. However, lower responsiveness of their spleen cells' proinflammatory cytokine production to concanavalin A (ConA) stimulation, along with preserved capacity of IL‐10 response, might be perceived as an indication of wild rats' reduced capability to cope with incoming environmental stimuli, but also as a means to limit tissue damage.     

TREATMENT OF UNILATERAL PERINEAL HERNIAS IN 2 MALE CHINCHILLAS (CHINCHILLA LANIGERA)

Two sexually intact adult male chinchillas were presented with a swelling in the perineal region. Radiographically both masses had a soft tissue opacity. Ultrasonography confirmed the tentative diagnosis of perineal hernia. In the first case the ultrasonographic examination revealed a fluid-filled structure inside the swelling, which was determined to be the urinary bladder. In the second case the hernia sac was filled with homogeneous tissue, belived to be fat. Subsequently, unilateral perineal herniorrhaphies including an internal obturator muscle flap transposition technique were performed. Both chinchillas recovered well with subsequent uneventful healing of the surgical sites. No long-term complications or recurrences of the perineal hernias were reported. This clinical report shows that perineal hernias occur in chinchillas and can be surgically treated with success.