Sperm chromatin stability in frozen-thawed semen is maintained over age in AI bulls

The aim of the present study was to investigate the effect of age of the sire on the in vitro quality of frozen-thawed (FT) bull spermatozoa, both when tested immediately postthaw (PT) and when assessed after cleansing and selection through a swim-up (SU) procedure. Semen samples from six Swedish Red and White Breed (SRB) artificial insemination (AI) bulls at age 1 and again, at 4 years were collected and frozen in 0.25 ml plastic straws. Also, semen was collected from six Estonian Holstein (EHF) bulls at the ages of 3, 5, and 7 years and likewise processed. The FT semen was tested for the susceptibility of sperm nuclear deoxyribonucleic acid (DNA) to undergo acid-induced denaturation in situ, as quantified by flow cytometry (FCM). The DNA denaturability was expressed as function alpha t, i.e., as the ratio of red (denaturated DNA) to red + green (total cellular DNA) fluorescence intensity. The results were expressed as the percentage of cells with high alpha t values, i.e., cells outside the main population (% COMP alpha t). Morphological evaluation of the same samples was performed to detect general and sperm head abnormalities and differences between ages. Fertility results were available as non-return rates (NRRs) for the semen of the sires when they were 1 year (SRB) and 3 years (EHF) old, varying from 62.2 to 70.7% in SRB and from 52.2 to 76.0% in EHF animals. The COMP alpha t values ranged from 0.5-3.6% (PT) to 0.2-1.7% (SU) for SRB bulls and from 0.4-1.8% (PT) to 0.2-1.5% (SU) for EHF bulls. Both breeds lacked differences between ages, either PT or after SU. However, the SU procedure yielded a significantly higher population of spermatozoa with stable DNA following acid-induced denaturation, than PT samples (p < 0.001). No correlation was detected between field fertility and chromatin stability. The results indicate that for these bull populations, the SU procedure was able to select spermatozoa with stable chromatin from the bulk samples. However, the use of DNA denaturation as a challenge to assess sperm chromatin stability did not offer a more accurate tool to evaluate sperm quality than the conventional, light microscopical evaluation of morphology.     

Evaluation of suitable reference genes for gene expression studies in bronchoalveolar lavage cells from horses with inflammatory airway disease

Background  

The stability of reference genes has a tremendous effect on the results of relative quantification of genes expression by quantitative polymerase chain reaction. Equine Inflammatory Airway Disease (IAD) is a common condition often treated with corticosteroids. The diagnosis of IAD is based on clinical signs and bronchoalveolar lavage (BAL) fluid cytology. The aim of this study was to identify reference genes with the most stable mRNA expression in the BAL cells of horses with IAD irrespective of corticosteroids treatment.     

The role of landscape structure in determining palynological and floristic richness

The associations between floristic and palynological richness and landscape structure were studied based on modern pollen?Cvegetation data from a patchy cultural landscape in southern Estonia (northern temperate vegetation zone). Nine study sites (small lakes and their surrounding vegetation) represent land cover gradient from closed forest to semi-open vegetation. Floristic richness (number of species) and floristic richness of pollen types (number of pollen-equivalent taxa) were used to describe the vegetation within the radius of 250?m from the pollen sampling sites. Palynological richness was calculated to describe the modern pollen samples diversity. Landscape structure was estimated on the basis of landscape openness and three landscape diversity measures: richness of community patches, Simpson evenness of community patches and Simpson diversity of community patches. To study the effect of the spatial scale of landscapes on the vegetation?Clandscape and pollen?Clandscape associations, landscape structure was estimated within eight radii (250?C2,000?m) around each lake. The results showed that landscape openness was the most important determinant of both floristic richness and palynological richness in southern Estonia and that landscape diversity estimated by Simpson diversity index was also significantly associated with the richness estimates. Floristic and palynological richness were significantly positively correlated with landscape structure within the radii greater than 1,000?m from the pollen sampling sites, which is similar to the estimated Relevant Source Area of Pollen in southern Estonia. We conclude that within one floristic or climatic region, palynological richness gives reliable estimates about the variation in floristic richness and landscape structure; however, caution must be taken when comparing pollen-inferred vegetation diversities from different regions or when interpreting fossil pollen records from times with highly different vegetation associations.     

Spatial structure and the effects of host and soil environments on communities of ectomycorrhizal fungi in wooded savannas and rain forests of Continental Africa and Madagascar

Mycorrhizal fungi play a key role in mineral nutrition of terrestrial plants, but the factors affecting natural distribution, diversity and community composition of particularly tropical fungi remain poorly understood. This study addresses shifts in community structure and species frequency of ectomycorrhizal (EcM) fungi in relation to host taxa, soil depth and spatial structure in four contrasting African ecosystems. We used the rDNA and plastid trnL intron sequence analysis for identification of fungi and host plants, respectively. By partitioning out spatial autocorrelation in plant and fungal distribution, we suggest that African EcM fungal communities are little structured by soil horizon and host at the plant species and family levels. These findings contrast with patterns of vegetation in these forests and EcM fungal communities in other tropical and temperate ecosystems. The low level of host preference indirectly supports an earlier hypothesis that pioneer Phyllanthaceae may facilitate the establishment of late successional Fabaceae and potentially other EcM host trees by providing compatible fungal inoculum in deforested and naturally disturbed ecosystems of tropical Africa.     

Ectomycorrhizal fungi of the Seychelles: diversity patterns and host shifts from the native Vateriopsis seychellarum (Dipterocarpaceae) and Intsia bijuga (Caesalpiniaceae) to the introduced Eucalyptus robusta (Myrtaceae), but not Pinus caribea (Pinaceae)

Ectomycorrhizal (ECM) fungi form highly diverse communities in temperate forests, but little is known about their community ecology in tropical ecosystems. Using anatomotyping and rDNA sequencing, ECM fungi were identified on root tips of the introduced Eucalyptus robusta and Pinus caribea as well as the endemic Vateriopsis seychellarum and indigenous Intsia bijuga in the Seychelles. Sequencing revealed 30 species of ECM fungi on root tips of V. seychellarum and I. bijuga, with three species overlapping. Eucalyptus robusta shared five of these taxa, whereas P. caribea hosted three unique species of ECM fungi that were likely cointroduced with containerized seedlings. The thelephoroid (including the anamorphic genus Riessiella), euagaric, boletoid and hymenochaetoid clades of basidiomycetes dominated the ECM fungal community of native trees. Two species of Annulatascaceae (Sordariales, Ascomycota) were identified and described as ECM symbionts of V. seychellarum. The low diversity of native ECM fungi is attributed to deforestation and long-term isolation of the Seychelles. Native ECM fungi associate with exotic eucalypts, whereas cointroduced ECM fungi persist in pine plantations for decades.     

A novel device detects a rapid ozone-induced transient stomatal closure in intact Arabidopsis and its absence in abi2 mutant

To follow stomatal responses to ozone (O₃) in different Arabidopsis lines, we constructed a rapid-response O₃ exposure/gas-exchange measurement device consisting of eight through-flow whole-rosette cuvettes. To separate rosette from roots and growth substrate, plant is grown through an agar-filled hole in a polished glass plate fixed on the pot. Following insertion of the plant, the plate forms air-tight bottom surface of the cuvette; thus the rosette is enclosed without touching it during any phase of the insertion of the plant to the cuvette. The device allows monitoring rapid responses in the stomatal function. For example, an acute exposure to 150 ppb O₃ decreased stomatal conductance to 60–70% of its initial value within 9–12 min. Thereafter, the conductance regained its preexposure value within further 30–40 min in spite of the continuing O₃ exposure. The transient decrease was absent in the abscisic acid-insensitive mutant abi2 defective in a class 2C protein phosphatase. This provides an in vivo confirmation that the early transient decrease in stomatal conductance is not a result of physical damage by the reactive oxygen species (ROS) formed from O₃ breakdown but reflects the biological action of ROS, transduced through a signalling cascade. Thus, the apparatus will be helpful in specifying complex molecular and genetic interactions in rapid responses in guard cells in vivo.