Effects of Photoperiod on the Apparent Viscosity of Leaf Cytoplasm in Kalanchoe blossfeldiana. I. A Method for Quantitative Estimation and its Sources of Error

An adaptation of the centrifuge method of determining cytoplasmicviscosity is described, suitable for the examination of leavesof higher plants exposed to different photoperiodic conditions.Leaf segments are centrifuged for several standard periods,usually i, 2, and 4 minutes, followed by immediate fixation,microscopic examination of hand-microtome sections, and thedetermination of the proportions of cells in the mesophyll regionwhose chloroplasts have been displaced. Among factors whichmay cause systematic errors, variations in cell size, chloroplastsize and chloroplast starch content have been found to causerelatively little error. Similarly, changes in water contentwhich cause up to 14 per cent loss of fresh weight have no largeor consistent effect. Significant effects may arise from diurnalchanges, or from differences in ambient and in growth temperature,as well as in leaf age and the region within the leaf that istested; they can all be minimized by appropriate sampling techniques.Any treatment effects revealed by the method are clearly notascribable to viscosity differences alone, but they are likelyto represent real changes in the physical state of the cytoplasm;they are therefore referred to as representing changes in ‘apparentviscosity’.     

Extension growth in Primary Cell-Walls with Special Reference to Hippuris vulgaris

A quantitative study of pit-field distribution in the longitudinalwalls of cortical parenchyma shows that pit-fields increasein number continuously during cell division and growth. A considerationof the data in relation to other information on pit-field distributionand to wider aspects of cell-wall extension suggests that pit-fieldmultiplication may be expected to be a characteristic featureof the growth of intercellular cell-wall surfaces in meristemcells.     

A New Noninvasive Method for Detecting Mammals From Birds' Nests

Abstract: Certain birds use mammal hair for the lining or structural strengthening of their nest. As a result, many bird nests can be regarded as natural hair snares. Preliminary studies indicate that analyses of hairs found in birds' nests are an effective method for detecting and identifying mammals that live in or migrate through an area and could be a useful tool to gain information about rare or hard to detect mammals. I documented 27 mammal taxa that were identified from hair collected from >3,000 nests. This study summarizes the results of 4 projects that represent application of this technique. This noninvasive method appears to be a useful tool for easily accessing basic faunistical data about mammal fauna of the given area.     

Distinct gene subsets in pterygia formation and recurrence: dissecting complex biological phenomenon using genome wide expression data

Background

Pterygium is a common ocular surface disease characterized by fibrovascular invasion of the cornea and is sight-threatening due to astigmatism, tear film disturbance, or occlusion of the visual axis. However, the mechanisms for formation and post-surgical recurrence of pterygium are not understood, and a valid animal model does not exist. Here, we investigated the possible mechanisms of pterygium pathogenesis and recurrence.

Methods

First we performed a genome wide expression analysis (human Affymetrix Genechip, >22000 genes) with principal component analysis and clustering techniques, and validated expression of key molecules with PCR. The controls for this study were the un-involved conjunctival tissue of the same eye obtained during the surgical resection of the lesions. Interesting molecules were further investigated with immunohistochemistry, Western blots, and comparison with tear proteins from pterygium patients.

Results

Principal component analysis in pterygium indicated a signature of matrix-related structural proteins, including fibronectin-1 (both splice-forms), collagen-1A2, keratin-12 and small proline rich protein-1. Immunofluorescence showed strong expression of keratin-6A in all layers, especially the superficial layers, of pterygium epithelium, but absent in the control, with up-regulation and nuclear accumulation of the cell adhesion molecule CD24 in the pterygium epithelium. Western blot shows increased protein expression of beta-microseminoprotein, a protein up-regulated in human cutaneous squamous cell carcinoma. Gene products of 22 up-regulated genes in pterygium have also been found by us in human tears using nano-electrospray-liquid chromatography/mass spectrometry after pterygium surgery. Recurrent disease was associated with up-regulation of sialophorin, a negative regulator of cell adhesion, and never in mitosis a-5, known to be involved in cell motility.

Conclusion

Aberrant wound healing is therefore a key process in this disease, and strategies in wound remodeling may be appropriate in halting pterygium or its recurrence. For patients demonstrating a profile of 'recurrence', it may be necessary to manage as a poorer prognostic case and perhaps, more adjunctive treatment after resection of the primary lesion.