The redistribution of soil water by tree root systems

Plant roots transfer water between soil layers of different water potential thereby significantly affecting the distribution and availability of water in the soil profile. We used a modification of the heat pulse method to measure sap flow in roots of Grevillea robusta and Eucalyptus camaldulensis and demonstrated a redistribution of soil water from deeper in the profile to dry surface horizons by the root system. This phenomenon, termed “hydraulic lift” has been reported previously. However, we also demonstrated that after the surface soils were rewetted at the break of season, water was transported by roots from the surface to deeper soil horizons – the reverse of the “hydraulic lift” behaviour described for other woody species. We suggest that “hydraulic redistribution” of water in tree roots is significant in maintaining root viability, facilitating root growth in dry soils and modifying resource availability. Received: 26 January 1998 / Accepted: 15 April 1998     

Distinct roles of synapsin I and synapsin II during neuronal development.

The synapsins are a family of neuron-specific proteins, associated with the cytoplasmic surface of synaptic vesicles, which have been shown to regulate neurotransmitter release in mature synapses and to accelerate development of the nervous system. Using neuronal cultures from mice lacking synapsin I, synapsin II, or both synapsins I and II, we have now found that synapsin I and synapsin II play distinct roles in neuronal development. Deletion of synapsin II, but not synapsin I, greatly retarded axon formation. Conversely, deletion of synapsin I, but not synapsin II, greatly retarded synapse formation. Remarkably, the deletion of both synapsins led to partial restoration of the wild phenotype. The results suggest that the synapsins play separate but coordinated developmental roles.     

Spatiotemporal distribution and the passive dispersal of fungal spores through HVAC systems

Heating, ventilation and air conditioning (HVAC) systems are widely used to regulate indoor temperature and air quality of modern buildings. The central supply and exhaust system cause the dispersal and removal of bioaerosols. This study presents results from ex situ experiments conducted to a better understanding of the spatiotemporal distribution, passive dispersal and removal of fungal spores through HVAC systems. The study was conducted in a 50 square meters by 3 m high instrument room in a research building with HVAC systems. Plates with Aspergillus flavus colony were attached upside down on the edge of the ceiling vent to imitate the mildew growing. Fungal spores were released for 10 min, collected and counted by the settle plate method in 2 h. Results show that A. flavus spores dispersed to 3.6 m in 2 min and were evenly distributed in the room within 8 min. The concentration of spores decreased from 48 to 3–6 CFU/plate after 60 min and was lower than 1% after 120 min. Our results suggest that airborne fungal spores disperse and remove by HVAC systems efficiently. Without the external and internal source, the HVAC system could greatly reduce the fungal amount in the indoor air to the background level within one hour. This study provided the observed data of the transmission and retention of internal or external biological contaminants through HVAC system.

     

Pericardial and pericardioperitoneal canal relationships to cardiac function in the white sturgeon (Acipenser transmontanus)

Sturgeons are primitive bony fishes and their hearts have structural features found in other primitive fishes. Sturgeons have a pericardioperitoneal canal (PPC), a one-way conduit into the peritoneum. A PPC also occurs in elasmobranchs (sharks and rays) and studies with that group demonstrate that pericardial pressure and pericardial fluid loss via the PPC affect stroke volume. A study of white sturgeon (Acipenser transmontanus) heart function was conducted to test for a comparable PPC and pericardial effects. White sturgeon-elasmobranch heart-function similarities include biphasic ventricular filling, a comparable operational pericardial pressure (-0.03 kPa), and a strongly negative pressure (-0.2 to -0.6 kPa) with complete pericardial fluid withdrawal. Differences include the white sturgeon's relatively smaller atrium and ventricle but a larger conus arteriosus. Although white sturgeon heart size is also smaller, its pericardial volume is disproportionately less (2.4 to 2.7 vs. 3.5 to 5.4 ml kg(-1) in elasmobranchs), meaning it has less scope for increasing stroke volume upon PPC fluid release. These differences may reflect the phylogenetic progression from the less complex operation of the elasmobranch heart, which lacks sympathetic innervation and has a mechanically mediated (PPC) stroke volume, to the condition in the more derived bony fishes which have sympathetic and parasympathetic regulation of both stroke volume and heart rate.     

beta-Internexin, a ubiquitous intermediate filament-associated protein

In this article we show a Triton-insoluble, intermediate filament-associated protein of approximately 70 kD to be expressed ubiquitously in diverse mammalian cell types. This protein, assigned the name beta-internexin, exhibits extreme homology in each of the various cell lines as demonstrated by identical limited peptide maps, similar mobilities on two-dimensional gels, and detection in Triton-soluble and -insoluble extracts. beta-Internexin also shares some degree of homology with alpha-internexin, an intermediate filament-associated protein isolated and purified from rat spinal cord, which accounts for the immunologic cross-reactivity displayed by these polypeptides. Light microscopic immunolocalization of beta-internexin with a monoclonal antibody (mAb-IN30) reveals it to be closely associated with the vimentin network in fibroblasts. The antigen is also observed to collapse with the vimentin reticulum during the formation of a juxtanuclear cap induced by colchicine treatment. Ultrastructural localization, using colloidal gold, substantiates the affinity of beta-internexin for cytoplasmic filaments and, in addition, demonstrates its apparent exclusion from the intranuclear filament network. We examine also the resemblance of beta-internexin to a microtubule-associated polypeptide and the constitutively synthesized mammalian heat shock protein (HSP 68/70).     

A Report on the Chromosome Numbers of Chinese Umbelliferae

Chromosome numbers are reported for 26 species and varieties of Umbelliferae which belong to 3 subfamilies and 19 genera in this paper. Of these, 13 counts are new records and some problems about chromosome numbers of Umbelliferae are simplydiscussed.     

Molecular characterization of messenger RNAs for 'pathogenesis related' proteins la, lb and lc, induced by TMV infection of tobacco

A cDNA library was made to poly(A)-containing RNA from tobacco mosaic virus (TMV)-infected Samsun NN tobacco plants and clones corresponding to mRNAs for the `pathogenesis-related' (PR) proteins 1a, 1b and 1c were identified. One clone was found to contain a complete copy of PR-1b mRNA. The structural organization of this RNA is: a leader sequence of 29 nucleotides, an open reading frame of 504 nucleotides encoding a 30 amino acid long signal peptide and a 138 amino acid long mature protein, and a 3'-non-coding region of 235 nucleotides. Two other clones were found to contain partial copies of PR-1a and PR-1c mRNAs. The data indicate an ~90% homology between the amino acid sequences of PR-1a, -1b and -1c. Using one of the clones as probe it was shown that in the TMV-inoculated lower leaves and the non-inoculated upper leaves of a tobacco plant, the PR-1 mRNAs become detectable from 2 and 8 days after inoculation, respectively.     

Statistical shape modelling of the thoracic spine for the development of pedicle screw insertion guides

Spinal fixation and fusion are surgical procedures undertaken to restore stability in the spine and restrict painful or degenerative motion. Malpositioning of pedicle screws during these procedures can result in major neurological and vascular damage. Patient-specific surgical guides offer clear benefits, reducing malposition rates by up to 25%. However, they suffer from long lead times and the manufacturing process is dependent on third-party specialists. The development of a standard set of surgical guides may eliminate the issues with the manufacturing process. To evaluate the feasibility of this option, a statistical shape model (SSM) was created and used to analyse the morphological variations of the T4–T6 vertebrae in a population of 90 specimens from the Visible Korean Human dataset (50 females and 40 males). The first three principal components, representing 39.7% of the variance within the population, were analysed. The model showed high variability in the transverse process (~ 4 mm) and spinous process (~ 4 mm) and relatively low variation (< 1 mm) in the vertebral lamina. For a Korean population, a standardised set of surgical guides would likely need to align with the lamina where the variance in the population is lower. It is recommended that this standard set of surgical guides should accommodate pedicle screw diameters of 3.5–6 mm and transverse pedicle screw angles of 3.5°–12.4°.

     

The Postnatal Development of the Cerebellum— A fMRI and Silver Study

Summary The aim of this study was to evaluate the postnatal development of the cerebella of the pig and to compare this with the activation of the fMRI. The cells in the cerebella were studied by silver technique and the activation of the fMRI in the cerebella was initiated by flexion and extension of the hind paw. Our results showed an increase of the branching of the cells of the cerebellar cortex postnatally, coordinated with registration of fMRI active sites in the cerebella at 6-month postnatal. We concluded that the full maturation of the cerebella was around 6-month postnatal in the pig.     

Two novel ubiquitin-fold modifier 1 (Ufm1)-specific proteases, UfSP1 and UfSP2

Ubiquitin-fold modifier 1 (Ufm1) is a recently identified new ubiquitin-like protein, whose tertiary structure displays a striking resemblance to ubiquitin. Similar to ubiquitin, it has a Gly residue conserved across species at the C-terminal region with extensions of various amino acid sequences that need to be processed in vivo prior to conjugation to target proteins. Here we report the isolation, cloning, and characterization of two novel mouse Ufm1-specific proteases, named UfSP1 and UfSP2. UfSP1 and UfSP2 are composed of 217 and 461 amino acids, respectively, and they have no sequence homology with previously known proteases. UfSP2 is present in most, if not all, of multicellular organisms including plant, nematode, fly, and mammal, whereas UfSP1 could not be found in plant and nematode upon data base search. UfSP1 and UfSP2 cleaved the C-terminal extension of Ufm1 but not that of ubiquitin or other ubiquitin-like proteins, such as SUMO-1 and ISG15. Both were also capable of releasing Ufm1 from Ufm1-conjugated cellular proteins. They were sensitive to inhibition by sulfhydryl-blocking agents, such as N-ethylmaleimide, and their active site Cys could be labeled with Ufm1-vinylmethylester. Moreover, replacement of the conserved Cys residue by Ser resulted in a complete loss of the UfSP1 and UfSP2 activities. These results indicate that UfSP1 and UfSP2 are novel thiol proteases that specifically process the C terminus of Ufm1.