PCR-RFLP and Sequencing of TrnS/trnfM Fragment of Enhalus Acoriodes From Sanur Coastal Waters, Bali, Indonesia: a Preliminary Study

This study aimed to evaluate the resolution of PCR-RFLP and sequencing of trnS/trnfM in detecting genetic diversity of seagrass Enhalus acoroides at Sanur Beach, Sindhu Beach and Semawang Beach. This research used six samples E. acoroides from each location. DNA extraction method followed Doyle and Doyle. PCR amplifications were done using primers P672/P673, P674/P675 and ITS4/ITS5 followed by digestion using restriction enzymes EcoRI, PstI, HindIII, BamHI, Rsa, Mva and HinfI. Sequencing analysis used PCR products of primers trnS/trnfM. Testing of DNA sequences of E. acoroides were conducted using BLAST (Basic Local Alignment Search Tool). DNA sequences were further analyzed using MEGA 5.2 software (Molecular Evolutionary Genetic Analysis) to evaluate variations of DNA. The sequence alignments were done using ClustalW software to determine the homology between the DNA sequences. The results showed that 18 samples of E. acoroides from Sanur, Sindhu and Semawang Beach have no polymorphism based on restriction enzyme analyses. Furthermore, sequencing of trnS/trnfM region of 18 samples E. acoroides showed that the sequences were identical

The Arabidopsis thaliana Brassinosteroid Receptor (AtBRI1) Contains a Domain that Functions as a Guanylyl Cyclase In Vitro

BACKGROUND: Guanylyl cyclases (GCs) catalyze the formation of the second messenger guanosine 3′,5′-cyclic monophosphate (cGMP) from guanosine 5′-triphosphate (GTP). Cyclic GMP has been implicated in an increasing number of plant processes, including responses to abiotic stresses such as dehydration and salt, as well as hormones. PRINCIPLE FINDINGS: Here we used a rational search strategy based on conserved and functionally assigned residues in the catalytic centre of annotated GCs to identify candidate GCs in Arabidopsis thaliana and show that one of the candidates is the brassinosteroid receptor AtBR1, a leucine rich repeat receptor like kinase. We have cloned and expressed a 114 amino acid recombinant protein (AtBR1-GC) that harbours the putative catalytic domain, and demonstrate that this molecule can convert GTP to cGMP in vitro. CONCLUSIONS: Our results suggest that AtBR1 may belong to a novel class of GCs that contains both a cytosolic kinase and GC domain, and thus have a domain organisation that is not dissimilar to that of atrial natriuretic peptide receptors, NPR1 and NPR2. The findings also suggest that cGMP may have a role as a second messenger in brassinosteroid signalling. In addition, it is conceivable that other proteins containing the extended GC search motif may also have catalytic activity, thus implying that a significant number of GCs, both in plants and animals, remain to be discovered, and this is in keeping with the fact that the single cellular green alga Chlamydomonas reinhardtii contains over 90 annotated putative CGs

Cyclic GMP modulates stomatal opening induced by natriuretic peptides and immunoreactive analogues

In this paper we demonstrate that compounds that promote stomatal opening such as kinetin, atrial natriuretic peptide (ANP) and plant natriuretic peptide immunoanalogues (irPNP) significantly elevate cGMP in guard cell protoplasts. Stomata opened by irPNP are induced to close in the presence of the guanylate cyclase inhibitor, LY 83583. The effect of cGMP on stomatal opening appears to be linked with Ca2+ levels. ANP, irPNP and 8-Br-cGMP all induce stomatal opening and this is inhibited by compounds that lower intracellular Ca2+ levels such as ethylene glycol bis(&beta;-aminoethyl ether) N,N,N&rsquo;,N&rsquo;-tetraacetic acid (EGTA), ruthenium red and procaine.<br /

Is the phosphate analogue phosphite interfering with plant phosphorus homeostasis and signalling?

Phosphorus (P) is a macronutrient that is essential for plant growth, but often has a low availability due to a low solution P pool and sorption to soil minerals. P is taken up by the roots of plants in the form of inorganic phosphate (Pi) and plants feature complex regulatory networks to maintain P homeostasis and optimise their Pi uptake and storage capacities to meet metabolic and developmental demand. Phosphite (Phi, HPO32-) is a more reduced form of P that is used as a biostat to enhance plant resistance against Phytophthora species. These pathogenic oomycetes are a major threat to both food security (Phytophthora infestans caused the Irish potato famine in the mid 19th century) and natural diversity (Phytophthora cinnamomi has been termed the ‘biological bulldozer’ due to its devastating effect on plant communities in many biodiversity hotspots around the globe). However, despite its successful marketing as a ‘fungicide’ relatively little is known about its longerterm impact on plant growth and development. Phi is believed to mimic Pi in suppressing the plant’s Pistarvation response and severely inhibits growth of plants with a low P status. Its uptake most likely proceeds via transporters of the PHT1 family and is highly sensitive to competitive inhibition by Pi. Here we show that Phi is not a perfect mimetic of Pi in suppressing Pi-starvation responses. While it does suppress root-hair formation and attenuate the expression of many Pi-starvation-induced genes, it does not reduce the expression of many other well known Pi-signalling genes. In contrast to Pi resupply, Phi addition actually leads to a severe inhibition of primary and secondary root elongation and an increase in lateral root density that is much more pronounced than under Pi starvation itself. Anthocyanin accumulation in older leaves is not completely reversed by supplying Phi instead of Pi to P-starved plants. This could be an indication for altered shoot Pi reallocation patterns in those plants. We show that Phi evokes a set of distinct physiological and molecular reactions that distinguish it from well characterised Pi-induced changes and therefore make it an excellent tool to study P-sensing and -signal-transduction pathways. This will also provide new insights into how Phi alters plant defence responses to boost their resistance against parasitic oomycetes

Identifikasi Makrozoobenthos di Tukad Bausan, Desa Pererenan, Kabupaten Badung, Bali

A macrozoobenthos study was conducted at Bausan River, Pererenan village, Badung regency, Bali between September and December, 2006. There were six sampling stations were determined purposively. At each station, five unit of square plots of 40 cm x 40 (in maximum solum depth) samples were taken. The result showed that there were seventeen species of macrozoobenthos were found. There was no protected species found in this study. The macrozoobenthos had 2,28 level of index diversity. This indicated that the ecosystem at this area was in a stable condition with a medium level of macrozoobenthos diversity

Plant natriuretic peptide active site determination and effects on cGMP and cell volume regulation

Natriuretic peptides (NP) were first identified in animals where they play a role in the regulation of salt and water balance. This regulation is partly mediated by intracellular changes in cyclic GMP (cGMP). NP immunoanalogues occur in many plants and have been isolated, with two NP encoding genes characterised in Arabidopsis thaliana L. (AtPNP-A and AtPNP-B). Part of AtPNP-A contains the region with homology to human atrial (A)NP. We report here on the effects of recombinant AtPNP-A and smaller synthetic peptides within the ANP-homologous region with a view to identifying the biologically active domain of the molecule. Furthermore, we investigated interactions between AtPNP-A and the hormone, abscisic acid (ABA). ABA does not significantly affect Arabidopsis mesophyll protoplast volume regulation, whereas AtPNP-A and synthetic peptides promote water uptake into the protoplasts causing swelling. This effect is promoted by the membrane permeable cGMP analogue, 8-Br-cGMP, and inhibited by guanylate cyclase inhibitors indicating that increases in cGMP are an essential component of the plant natriuretic peptides (PNP) signalling cascade. ABA does not induce cGMP transients and does not affect AtPNP-A dependent cGMP increases, hence the two regulators differ in their second messenger signatures. Interestingly, AtPNP-A significantly delays and reduces the extent of ABA stimulated stomatal closure that is also based on cell volume regulation. We conclude that a complex interplay between observed PNP effects (stomatal opening and protoplast swelling) and ABA is likely to be cell type specific.<br /