Comment on "A centrosome-independent role for gamma-TuRC proteins in the spindle assembly checkpoint"

Müller et al. (Reports, 27 October 2006, p. 654) proposed a role for microtubule nucleation in mitotic checkpoint signaling. However, their observations of spindle defects and mitotic delay after depletion of gamma-tubulin ring complex (gamma-TuRC) components are fully consistent with activation of the established pathway of checkpoint signaling in response to incomplete or unstable interactions between kinetochores of mitotic chromosomes and spindle microtubules.     

Mammary carcinoma in a tiger (Panthera tigris): morphological and immunohistochemical study

The histologic and immunohistochemical features of a case of mammary gland carcinoma are described in a 14-yr-old female tiger (Panthera tigris). Immunoreactivity to estrogen receptor (ER), progesterone receptor (PR), tumoral protein 53 (p53), vascular endothelial growth factor (VEGF), human epidermal growth factor receptor 2 (HER-2), and cyclooxigenase-2 (COX-2) was investigated. Neoplastic cells were negative for ER, PR, and p53 but showed positivity for VEGF, HER-2, and COX-2, both in the primary and the metastatic lesions. Histopathologic findings and immunohistochemistry results suggested that the malignant behavior of the reported case could be comparable with some aggressive cat mammary carcinomas.     

Differentially-regulated defence genes in Malus domestica during phytoplasma infection and recovery

To improve knowledge about plant/phytoplasma interactions and, in particular, about the ‘recovery’ phenomenon in previously-infected plants, we investigated and compared expression levels of several defence-related genes (four pathogenesis-related proteins and three jasmonate-pathway marker enzymes) in apple plants showing different states of health: vigorous (healthy), phytoplasma-infected, and recovered. Real Time-PCR analyses demonstrated that genes are differentially expressed in apple leaf tissue according to the plants’ state of health. Malus domestica Pathogenesis-Related protein (MdPR) 1, MdPR 2 and MdPR 5 were significantly induced in leaves of diseased and symptomatic plants compared to leaves of those plants that were healthy or recovered. On the other hand, levels of all the jasmonate (JA)-pathway marker genes that we selected for this study, were up-regulated in the leaves of recovered plants compared to the diseased ones. In conclusion, our study demonstrated that two different sets of defence genes are involved in the interactions between apple plants and ‘Candidatus Phytoplasma mali’ (‘Ca. P. mali’) and that these genes are differentially expressed during phytoplasma infection or recovery.     

Radiographic vertebral left atrial size: A reference interval study in healthy adult dogs

Thoracic radiography is a useful technique for the evaluation of cardiac dimensions, especially when echocardiography is not possible. The vertebral left atrial size (VLAS) has recently been proposed as a new radiographic method for quantifying left atrial dimensions in dogs. The aims of this retrospective, reference interval, observational study were to describe values for VLAS in a group of healthy adult dogs and to compare intraobserver and interobserver agreement for VLAS versus vertebral heart score (VHS) methods. Thoracic radiographs of 80 healthy adult dogs were evaluated. Normal left atrial size was determined based on an echocardiographic left atrial‐to‐aorta ratio < 1.6. The VLAS and vertebral heart score values were measured from right lateral radiographs. The correlations between VLAS, the vertebral heart score, and the left atrial‐to‐aorta ratio were evaluated. The effects of body weight, sex, and age were also tested using regression analyses. The median value of VLAS were 1.9, with a reference interval of 1.4‐2.2. A positive correlation was found between VLAS and vertebral heart score values (r = 0.53; P < .0001). No effect of body weight, sex, and age on VLAS was detected. Excellent intraobserver and interobserver agreements were found for both VLAS and vertebral heart score methods (intraclass correlation coefficients ≥ 0.91). Findings from this sample of healthy dogs indicated that VLAS is a repeatable radiographic method for quantifying left atrial size. Further studies are warranted to evaluate this measure in clinically affected dogs.     

Effect of soil humic substances on surface redox activity of oat roots

The effect of a low molecular weight (<5kDa, LMW) and a high molecular weight (>5kDa, HMW) humic fractions on surface redox activities of oat roots was studied. Oxidation of the electron donor NADH and reduction of the artificial electron acceptor ferricyanide [K3Fe(CN)6] exogenously supplied to the roots both alone or in combination, was measured in the presence or absence of soil humic substances. HMW humic fraction inhibited NADH oxidation either in the presence or absence of ferricyanide, while LMW humic fraction inhibited NADH: ferricyanide oxidoreductase activity due to the contemporary addition of the two redox compounds to the solution bathing the roots. NADH: ferricyanide oxido‐reduction was partially due to the release of substances from the roots. However, the presence of soil humic fractions (LMW or HMW) did not significantly modify this behaviour. Rather, the inhibitory effect of soil humic substances was even more evident when the oxidoreduction solely due to the root activity was considered. The results confirm the presence of multiple types of oxidoreductase activities at the surface of oat roots and show that the two humic fractions HMW and LMW may differently affect these activities. Partial inhibition of NADH oxidase activity is interpreted as a possible way of interference of humic substances with metabolic processes involved in cell wall formation. The effects on surface redox activities are discussed in terms of the role of soil humic substances in promotion of plant growth.     

Protein Characterization of Protein Bodies from Cotyledons of Mucuna pruriens (L.) DC

Seeds of Mucuna pruriens (L.) DC. (Fabaceae) were analyzed for protein composition of protein bodies isolated from cotyledons. Protein bodies were successfully separated by Lympholyte and those of dry seeds, observed by scanning electron microscope, were elliptical or spherical in shape with a diameter of 5–12 μm. Protein content in dry seed protein bodies was 10.6 mg/g dry weight. Globulin was the largest protein fraction isolated (62.5 %), followed by albumin (18.3 %), glutelin (15.8 %) and prolamin (3.4 %). The prolamin fraction and high glutelin content are uncommon in legumes. SDS-PAGE of albumins, globulins, prolamins and glutelins provided different band numbers and molecular weights under reducing and non reducing conditions and suggested that the albumin fraction is rich in disulphide bonds.     

Complementary UV-Absorption of Mycosporine-like Amino Acids and Scytonemin is Responsible for the UV-Insensitivity of Photosynthesis in Nostoc flagelliforme

Mycosporine-like amino acids (MAAs) and scytonemin are UV-screening compounds that have presumably appeared early in the history of life and are widespread in cyanobacteria. Natural colonies of the UV-insensitive Nostoc flagelliforme were found to be especially rich in MAAs (32.1 mg g DW⁻¹), concentrated in the glycan sheath together with scytonemin. MAAs are present in the form of oligosaccharide-linked molecules. Photosystem II activity, measured using PAM fluorescence and oxygen evolution, was used as a most sensitive physiological parameter to analyse the effectiveness of UV-protection. Laboratory experiments were performed under controlled conditions with a simulated solar radiation specifically deprived of UV-wavebands with cut-off filters (295, 305, 320, 345 and 395 nm). The UV-insensitivity of N. flagelliforme was found to cover the whole UV-A (315–400 nm) and UV-B (280–320 nm) range and is almost certainly due to the complementary UV-absorption of MAAs and scytonemin. The experimental approach used is proposed to be suitable for the comparison of the UV-protection ability in organisms that differ in their complement of UV-sunscreen compounds. Furthermore, this study performed with a genuinely terrestrial organism points to the relevance of marine photoprotective compounds for life on Earth, especially for the colonization of terrestrial environments.