Gonzalez MA, Gomez PI, Montoya R
Comparison of
PCR-RFLP analysis of the ITS region with morphological criteria of various
strains of Dunaliella
J APPL PHYCOL 10 (6): 573-580 1998
Abstract:
The genus Dunaliella comprises 28 species defined
primarily by morphological and physiological criteria, which vary considerably
depending on growth conditions. Concomitantly, the taxonomic status of various
species is uncertain. To confirm the taxonomic identity and to better
understand the relationship within Dunaliella, seven taxa (D. salina, D. bardawil, D. tertiolecta, D. parva, D. viridis, D. lateralis, D. peircei)
were compared using RFLP analysis of the nuclear rDNA
repeats, specifically the internal transcribed spacer regions, including the
5.8S rRNA gene. Volvox
aureus was used as an outgroup. A single ITS PCR amplification product was
obtained for each taxon. An ITS fragment of ca. 640 bp was present in all the taxa
within the subgenus Dunaliella, except for D. salina CCMP 1303 (ca. 540 bp) and
D. lateralis (subgenus Pascheria)
(ca. 600 bp). A cluster analysis based on the
presence or absence of bands generated by digestion of the PCR product with 8
restriction endonucleases (DpnI,
HhaI, EcoRI, PVuII, TaqI, HaeIII,
MspI, StyI)
revealed no correlation between the genetic relationship inferred from the
ITS-RFLP data and the morpho-physiological attributes
used for taxonomy. In addition, differences in morphology, physiology and in
the length and restriction fragment patterns of the ITS
region of D. salina CCMP 1303 suggest that this
strain does not belong to Dunaliella.
Kobl I, Kirk DL, Schmitt R
Quantitative
PCR data falsify the chromosomal endoreduplication
hypothesis for Volvox
carteri (Volvocales, Chlorophyta)
J PHYCOL 34 (6): 981-988 DEC 1998
Abstract:
Two conflicting hypotheses for chromosome replication in the Volvocaceae, one postulating multiple rounds of replication
prior to cell division (endoreduplication) and the
other claiming a canonical sequence of one round of nuclear DNA replication
preceding each cell division, have been tested experimentally. Competitive PCR
of the single-copy actin gene (target) of Volvox carteri f. nagariensis Iyengar and a
shortened gene version (competitor) containing the same primer binding sites
were used to assess the genome equivalents present in a given number of cells.
Determining the molar ratio of the PCR products generated from target DNA
(extracted from a known number of cells) acid defined numbers of competitor
molecules revealed that Volvox embryos between
the one- and 16-cell stages possess an average of between one and two-but never
more than two-copies of the actin gene. This led us
to conclude that the number of genome equivalents per nucleus in dividing Volvox embryos varies only between one and two and
that, unlike the case predicted by endoredduplication,
the nuclear genome undergoes only one round of replication prior to each cell
division.
Sekimoto H, Fukumoto R, Dohmae N, et al.
Molecular
cloning of a novel sex pheromone responsible for the release of a different sex
pheromone in Closterium peracerosum-strigosum-littorale
complex
PLANT CELL PHYSIOL 39 (11): 1169-1175 NOV 1998
Abstract:
A sex pheromone, protoplast-release-inducing protein (PR-IP) inducer, of the Closterium peracerosum-strigosum-littorale
complex is known to induce the release of PR-IF, from mating-type plus (mtf) cells during sexual reproduction. The purified PR-IF
inducer was treated with trypsin to obtain internal
peptides for determination of partial amino acid sequences. Using these
sequences, oligonucleotides were synthesized and used
as primers for the combined reverse transcription-PCR, A 296 bp cDNA fragment was amplified,
permitting the cloning of corresponding full length cDNA
(CpPI; Closterium peracerosum-strigosum-littorale complex PR-IF inducer). The
deduced amino acid sequence of CpPI encodes a protein
of 212 amino acid residues of M-r 23,071 whereas portion of the peptide
secreted is predicted to have 142 amino acid residues of M-r 15,717 and shows
no significant similarity with known proteins. The predicted protein has three
possible consensus sequences for asparagine-linked glycosylation site. The CpPI gene
was expressed when mating-type minus (mt(-)) cells were incubated at a low cell density in the
light. Nitrogen deprivation from the medium enhances expression of the CpPI gene. An analysis by genomic Southern hybridization
revealed that the cDNA probe hybridized to several
DNA fragments obtained from both the genome of mt(-) and mt(+) cells. However, in mt- cells, transcripts for the PR-IF inducer could not be
detected by Northern hybridization.
Schirmer A, Kolter R
Computational
analysis of bacterial sulfatases and their modifying
enzymes
CHEM BIOL 5 (8): R181-R186 AUG 1998
Abstract:
The sequence analysis of enzymes that might modify bacterial sulfatases should be useful in the task of identifying the
human sulfatase-modifying homologs
enzymes that are defective in the rare inherited disease multi sulfatase deficiency.
Gladyshev MI, Sushchik NN, Kalachova GS, et al.
The effect of
algal blooms on the disappearance of phenol in a small forest pond
WATER RES 32 (9): 2769-2775 SEP 1998
Abstract:
Using experimental microecosystems the kinetics of
phenol disappearance in small forest pond waters (
von Figura K, Schmidt B, Selmer T, et al.
A novel
protein modification generating an aldehyde group in sulfatases: its role in catalysis and disease
BIOESSAYS 20 (6): 505-510 JUN 1998
Abstract:
In multiple sulfatase deficiency, a rare human lysosomal storage disorder, all known sulfatases
are synthesized as catalytically poorly active polypeptides. Analysis of the
latter has shown that they lack a protein modification that was detected in all
members of the sulfatase family. This novel protein
modification generates a 2-amino-3-oxopropanoic acid (C alpha-formylglycine) residue by oxidation of the thiol group of a cysteine that is
conserved among all eukaryotic sulfatases, The
oxidation occurs in the endoplasmic reticulum at a stage when the nascent
polypeptide is not yet folded. The aldehyde is part
of the catalytic site and is likely to act as an aldehyde
hydrate. One of the geminal hydroxyl groups accepts
the sulfate during sulfate ester cleavage leading to the formation of a
covalently sulfated enzyme intermediate. The other hydroxyl is required for the
subsequent elimination of the sulfate and regeneration of the aldehyde group. In some prokaryotic members of the sulfatase gene family, the DNA sequence predicts a serine
residue, and not a cysteine, Analysis of one of these
prokaryotic sulfatases, however, revealed the
presence of the C alpha-formylglycine indicating that
the aldehyde group is essential for all members of
the sulfatase family and that it can be generated
from either cysteine or serine, (C) 1998 John Wiley
& Sons, Inc.
Arai S, Takahashi H, Takano H, et al.
Isolation,
characterization, and chromosome mapping of an actin
gene from the primitive green alga, Nannochloris bacillaris (Chorophyceae)
J PHYCOL 34 (3): 477-485 JUN 1998
Abstract:
Historically, the genus Nannochloris has been
classified using the morphology of cell division, although the mechanics of
division remain relatively poorly understood. Nannochloris
bacillaris reproduces by binary fission. Microscopic
observation with fluorescein isothiocyanate-phaloloidin
showed that actin filaments localized near the
nucleus and appeared as a ring- or beltlike structure
in the septum-forming area in the middle of the cell during cell division. In
primitive unicellular Chlorophyta such as N. bacillaris, actin is also thought
to play important roles in nuclear migration and cell division. The N. bacillaris actin gene has three exons and two introns defined by
two exon-intron junctions with splice site consensus
sequences. The two introns are located at codons specifying amino acids 3/4 and 47/48. One of these, intron position 3/4, is conserved in the actin gene of Saccharomyces cerevisiae. The actin gene
product was predicted to be 378 amino acids long with an estimated molecular
weight of 42 kDa. There is only one copy of the actin gene in the N. bacillaris
genome. Nannochloris bacillaris
has 14 chromosomes that range in size from 230 kb to 3000 kb, and the total
size of the genome was estimated to be 20.3 Mb. The actin
gene is on either chromosome XI or XII. In a phylogenetic
tree based on the actin gene sequence, N. bacillaris diverged before the divergence of Volvox, Chlamydomonas, and
higher plants, and very shortly after the radiation of the Rhodophyta.
Amon P, Haas E, Sumper M
The
sex-inducing pheromone and wounding trigger the same set of genes in the multicellular green alga Volvox
PLANT CELL 10 (5): 781-789 MAY 1998
Abstract:
The sex-inducing pheromone of the multicellular green
alga Volvox carteri
is a glycoprotein that triggers development of males and females at a
concentration <10(-16) M. By differential screening of a cDNA
library, two novel genes were identified that are transcribed under the control
of this pheromone. Unexpectedly, one gene product was characterized as a lysozyme/chitinase, and the other gene product was shown to
encode a polypeptide with a striking modular composition. This polypeptide has
a cysteine protease domain separated by an extensin-like module from three repeats of a chitin binding
domain. In higher plants, similar protein families are known to play an
important role in defense against fungi. Indeed, we found that the same set of
genes triggered by the sexual pheromone was also inducible in V. carteri by wounding.
Hallmann A, Godl K, Wenzl S, et al.
The highly efficient
sex-inducing pheromone system of Volvox
TRENDS MICROBIOL 6 (5): 185-189 MAY 1998
Abstract:
The green alga Volvox is one of the simplest multicellular organisms and is capable of both asexual and
sexual reproduction. Sexual development is initiated by a glycoprotein
pheromone that acts at a concentration below 10(-16) M. The extracellular
matrix (ECM) appears to play a key role in signal amplification: several ECM
proteins contain a domain with homology to the sex-inducing pheromone.
El-Naggar MEE, Shaaban-Dessouki SA, Abdel-Hamid MI, et al.
Studies on
the phytoplankton populations and physico-chemical
conditions of treated sewage discharged into Lake Manzala
in Egypt
MICROBIOLOGICA 21 (2): 183-196 APR 1998
Abstract:
Over a full year, the phytoplankton populations and physico-chemical
conditions of treated sewage discharged into
A remarkable seasonal variation in species
composition and standing crop of the phytoplankton populations was noted during
the study. The total phytoplankton standing crop appeared to be mainly
dependent on the growth of certain species viz., Oscillatoria
chalybea, O. princepes, O. tenuis, Microcystis aeruginosa, Anabaena constricta (Cyanophyta), Nitzschia obtusa, Bacillaria paradoxa, Cocconeis placentula, Cyclotella meneghiniana (Bacillariophyta), Pandorina morum, Volvox sp. (Chlorophyta)
and Phacus curvicauda (Euglenophyta). The continuous presence of Anabaena constricta and Nitzschia palea was recorded in the treated sewage. The least
represented algal divisions were Pyrrhophyta and Cryptophyta, both in terms of quality and quantity.The data indicate that the secondary effluents
were unstable in their chemical features and grossly polluted. Therefore, the
treatment systems must treat the discharged sewage to a tertiary level before
discharging into
Corrette-Bennett J, Rosenberg M, Przybylska M, et al.
Positional
cloning without a genome map: Using 'Targeted RFLP Subtraction' to isolate
dense markers tightly linked to the regA locus of Volvox carteri
NUCLEIC ACIDS RES 26 (7): 1812-1818 APR 1 1998
Abstract:
The ability to isolate genes defined by mutant phenotypes has fueled the rapid
progress in understanding basic biological mechanisms and the causes of
inherited diseases. Positional cloning, a commonly used method for isolating
genes corresponding to mutations, is most efficiently applied to the small
number of model organisms for which high resolution genetic maps exist. We
demonstrate a new and generally applicable positional cloning method that
obviates the need for a genetic map. The technique is based on Restriction
Fragment Length Polymorphism (RFLP) Subtraction, a method that isolates RFLP
markers spanning an entire genome, The new method,
Targeted RFLP Subtraction (TRS), isolates markers from a specific region by
combining RFLP Subtraction with a phenotypic pooling strategy. We used TRS to
directly isolate dense markers tightly linked to the regA
gene of the eukaryotic green alga Volvox, As a generally applicable method for saturating a small
targeted region with DNA markers, TRS should facilitate gene isolation from
diverse organisms and accelerate the process of physically mapping specific
regions in preparation for sequence analysis.
ten Lohuis MR, Miller DJ
Genetic
transformation of dinoflagellates (Amphidinium and Symbiodinium):
expression of GUS in microalgae using heterologous promoterconstructs
PLANT J 13 (3): 427-435 FEB 1998
Abstract:
Genetic transformation of two dinoflagellates (Amphidinium sp., Symbiodinium microadriaticum) was achieved using plasmid constructs
containing the neomycin phosphotransferase gene (nptll) fused to the Agrobacterium
nos promoter, or the hygromycin
B phosphotransferase gene (hpt)
fused to the bidirectional Agrobacterium p1'2'
promoter. Gene transfer into intact (walled) dinoflagellate
cells was achieved by agitation in the presence of silicon carbide (SiCa) whiskers. Transformation rates of 5-24 transformants per 10(7) cells were obtained. Southern
hybridization of transformants revealed stable
integration of multiple copies of the constructs. Activity of integrated copies
of the beta-glucoronidase (GUS) reporter gene coupled
to the cauliflower mosaic virus 35S promotor or the
p1'2' promoter was confirmed both histochemically and
fluorometrically. This is the first report of
successful application bf heterologous and widely
used promoter and reporter genes in microalgae, and
is the first demonstration of transformation of a dinoflagellate.
There appear to be no substantial barriers to transformation of Amphidinium and Symbiodinium,
which must now be considered as the first of the dinoflagellate
genera accessible to genetic manipulation.
Miller SM, Kirk DL
glsA, a Volvox gene required for
asymmetric division and germ cell specification encodes a chaperone-like
protein
MOL BIOL CELL 9: 1694 Suppl. S NOV 1998
Bell G
Volvox -
Molecular-genetic origins of multicellularity and
cellular differentiation
SCIENCE 282 (5387): 248-248
Sumper M, Hallmann A
Biochemistry
of the extracellular matrix of Volvox
INT REV CYTOL 180: 51-85 1998