Morphologies and elemental compositions of calcium crystals in phyllodes and branchlets of Acacia robeorum (Leguminosae: Mimosoideae)

Background and Aims

Formation of calcium oxalate crystals is common in the plant kingdom, but biogenic formation of calcium sulfate crystals in plants is rare. We investigated the morphologies and elemental compositions of crystals found in phyllodes and branchlets of Acacia robeorum, a desert shrub of north-western Australia.

Methods

Morphologies of crystals in phyllodes and branchlets of A. robeorum were studied using scanning electron microscopy (SEM), and elemental compositions of the crystals were identified by energy-dispersive X-ray spectroscopy. Distributional patterns of the crystals were studied using optical microscopy together with SEM.

Key Results

According to the elemental compositions, the crystals were classified into three groups: (1) calcium oxalate; (2) calcium sulfate, which is a possible mixture of calcium sulfate and calcium oxalate with calcium sulfate being the major component; and (3) calcium sulfate · magnesium oxalate, presumably mixtures of calcium sulfate, calcium oxalate, magnesium oxalate and silica. The crystals were of various morphologies, including prisms, raphides, styloids, druses, crystal sand, spheres and clusters. Both calcium oxalate and calcium sulfate crystals were observed in almost all tissues, including mesophyll, parenchyma, sclerenchyma (fibre cells), pith, pith ray and cortex; calcium sulfate · magnesium oxalate crystals were only found in mesophyll and parenchyma cells in phyllodes.

Conclusions

The formation of most crystals was biologically induced, as confirmed by studying the crystals formed in the phyllodes from seedlings grown in a glasshouse. The crystals may have functions in removing excess calcium, magnesium and sulfur, protecting the plants against herbivory, and detoxifying aluminium and heavy metals.     

A low watering treatment alters biomass allocation and growth rate but not heteroblastic development in an <Emphasis Type="Italic">Acacia</Emphasis> species

Key message

The Acacia phyllode leaf form is hypothesised to be an adaptation to drought. However, in this experiment, the timing of phyllode development was not related to a low water treatment.

Abstract

Acacia species have markedly different leaf forms known as compound leaves, transitional leaves, and phyllodes, also known as heteroblastic development. The different leaf types are thought to confer an advantage under varying moisture regimes, with phyllodes favoured in drier conditions. The hypothesis that phyllodes develop earlier under low water treatment was tested in this experiment. Three watering level treatments (100, 50, and 25 %) were imposed on seedlings of A. implexa to assess developmental traits (leaf emergence, initial onset of transitional leaves, and phyllodes), biomass allocation patterns (root, stem, compound leaf area/mass, transitional leaf area/mass, and phyllode area/mass), and leaf anatomy traits (epidermis, palisade and spongy mesophyll, and stomatal density). Across watering treatments, there was no difference in the developmental onset of transitional leaves or phyllodes (produced at the 6th and 9th nodes, respectively). Under low watering treatment, there was a decrease in stem height per unit stem diameter, shorter internodes, and greater allocation of biomass to roots. There was no significant difference in leaf anatomy traits. Under the low watering treatment, there was less compound leaf area and mass due to leaf shedding. In this experiment, the low watering treatment did not favour phyllode development at the expense of compound leaf development. Rather, it was found that A. implexa responds to a low water treatment similarly to many other plant species: increased allocation to roots, increased stem area per unit stem height, decrease in leaf area through senescence of older leaves, and lower relative growth rates.

     

Quantitative relationship between synonymous codon usage bias and GC composition across unicellular genomes

Background  

Codon usage bias has been widely reported to correlate with GC composition. However, the quantitative relationship between codon usage bias and GC composition across species has not been reported.     

Expression of HOXA11 in the mid-luteal endometrium from women with endometriosis-associated infertility

Background  

A decrease in HOXA11 expression in eutopic mid-secretory endometrium has been found in women with endometriosis-associated infertility.     

Validation of rheumatoid arthritis diagnoses in health care utilization data

Introduction  

Health care utilization databases have been increasingly used for studies of rheumatoid arthritis (RA). However, the accuracy of RA diagnoses in these data has been inconsistent.     

The orthology of HLA-E and H2-Qa1 is hidden by their concerted evolution with other MHC class I molecules

Background  

Whether MHC molecules undergo concerted evolution or not has been the subject of a long-standing debate.     

Urinary protein profiling in hyperactive delirium and non-delirium cardiac surgery ICU patients

Background  

Suitable biomarkers associated with the development of delirium are still not known. Urinary proteomics has successfully been applied to identify novel biomarkers associated with various disease states, but its value has not been investigated in delirium patients.     

Characterization of exceptionally thermostable single-stranded DNA-binding proteins from <Emphasis Type="Italic">Thermotoga maritima</Emphasis> and <Emphasis Type="Italic">Thermotoga neapolitana</Emphasis>

Background  

In recent years, there has been an increasing interest in SSBs because they find numerous applications in diverse molecular biology and analytical methods.     

Molecular characterization of the PhoPQ-PmrD-PmrAB mediated pathway regulating polymyxin B resistance in <Emphasis Type="Italic">Klebsiella pneumoniae</Emphasis> CG43

Background  

The cationic peptide antibiotic polymyxin has recently been reevaluated in the treatment of severe infections caused by gram negative bacteria.     

The predictive role of serum and bronchoalveolar lavage cytokines and adhesion molecules for acute respiratory distress syndrome development and outcome

Background  

The predictive role of many cytokines and adhesion molecules has not been studied systematically in acute respiratory distress syndrome (ARDS).     

Multistable and multistep dynamics in neutrophil differentiation

Background  

Cell differentiation has long been theorized to represent a switch in a bistable system, and recent experimental work in micro-organisms has revealed bistable dynamics in small gene regulatory circuits. However, the dynamics of mammalian cell differentiation has not been analyzed with respect to bistability.     

Reduced responsiveness is an essential feature of chronic fatigue syndrome: A fMRI study

Background  

Although the neural mechanism of chronic fatigue syndrome has been investigated by a number of researchers, it remains poorly understood.     

Adiponectin is a potential catabolic mediator in osteoarthritis cartilage

Introduction  

Adiponectin has been implicated in the pathogenesis of osteoarthritis (OA). We studied the effects of adiponectin on the OA cartilage homeostasis.     

On finding minimal absent words

Background  

The problem of finding the shortest absent words in DNA data has been recently addressed, and algorithms for its solution have been described. It has been noted that longer absent words might also be of interest, but the existing algorithms only provide generic absent words by trivially extending the shortest ones.     

Increased expression of heat shock protein 105 in rat uterus of early pregnancy and its significance in embryo implantation

Background  

Heat shock proteins (Hsps) are a set of highly conserved proteins, Hsp105, has been suggested to play a role in reproduction.     

Health-related quality of life in adults with epilepsy: the effect of age,age at onset and duration of epilepsy in a multicentre Italian study

Background  

The potential effect of age-related factors on health-related quality of life (HRQOL) of patients with epilepsy has rarely been analyzed in the literature.     

Serious limitations of the QTL/Microarray approach for QTL gene discovery

Background  

It has been proposed that the use of gene expression microarrays in nonrecombinant parental or congenic strains can accelerate the process of isolating individual genes underlying quantitative trait loci (QTL). However, the effectiveness of this approach has not been assessed.     

Generation of an external guide sequence library for a reverse genetic screen in Caenorhabditis elegans

Background  

A method for inhibiting the expression of particular genes using external guide sequences (EGSs) has been developed in bacteria, mammalian cells and maize cells.