Vol. 25 - Issue 3 - 2001
PRIMITIVE FORMS OF MEIOSIS: THE POSSIBLE EVOLUTION
OF MEIOSIS
ALBERTO J. SOLARI
Centro de Investigaciones en Reproducción, Facultad de Medicina
(UBA), Buenos Aires (1121), ARGENTINA
Key words: meiosis, evolution, protists, synaptonemal complex
ABSTRACT:
Meiosis is a basic process of most eukaryotes, as it forms with conjugation
the basis of sexual reproduction. As sex seems to be present in the vast majority
of eukaryotes, the origin of meiosis is presently unknown. Protists having
optional or alternative sexual and asexual cycles seem to be the best targets
for research on the evolution of meiosis. While the budding yeast Saccharomyces
cerevisiae shows an elaborate and well-known meiotic process, the fission
yeast Schizosaccharomyces pombe, has a much simpler meiosis, which may show
some of the most primitive features of meiotic mechanisms. The present availability
of whole genome sequences of many bacteria and some protists is revealing
that eukaryotic sexual reproduction has recruited some prokaryotic processes
for its own development. Some of these processes are analyzed and the basic
role of chromosome linearity and telomere constitution in the development
of meiosis is underlined.
ESTROGEN RECEPTORS
IN MAST CELLS FROM ARTERIAL WALLS
S. NICOVANI , M.I. RUDOLPH
Departamento de Farmacología, Facultad de Ciencias Biológicas,
Universidad
de Concepción, casilla 160-C, 4080831- Concepción. Chile.
Key words: arterial vessel, atherosclerosis,
chymase, estrogen receptors, mast cell.
ABSTRACT:
We examined the presence of estrogen receptors (ER) in vascular mast cells
and a possible genomic effect of estrogens on the expression of mast cell
(MC) mediators such as chymase, TNFa, NOS and IL-10, which are known to affect
the course of atherosclerosis. Immunocytochemical detection of mast cell tryptase
and the co-localization of ERs in MCs from abdominal aortic vessels from 10
fertile woman, 10 postmenopausal women and 15 men was performed. The genomic
expression of IL-10, TNFa, and NOS was analyzed by RT-PCR and chymase activity
by spectrophotometry after 24 h incubation with 17-b estradiol (0.2-0.5 ng/mL)
in rat purified peritoneal MCs.
A similar number of MCs were found in both intima and adventitia layers from
men, and fertile and postmenopausal women, while ERs were detected only in
the arterial walls from fertile women. The mRNA expressions of IL-10 and TNFa,
as well as chymase activity, were not affected. A moderate increment of NO
and both NOS, and a reduction in TNFa cytotoxicity was observed after incubating
peritoneal MCs with 17- b estradiol at a concentration of 0.5 ng/mL. Taken
together, these results indicate that vascular MCs express ERs. The data demonstrate
that estrogens can directly modify vascular MC activity. This is a novel mechanism
of synergistic cooperation for the protective role of estrogens in the genesis
of atherosclerosis.
MICROPROPAGATION
OF Prosopis chilensis (Mol.) STUNTZ FROM YOUNG AND MATURE PLANTS
L.A. CARO1, P.A. POLCI1, L.I. LINDSTRÖM1, C.V. ECHENIQUE1,2
, AND L.F. HERNÁNDEZ1,3
1 Departamento de Agronomía, Universidad
Nacional del Sur, San Andrés 800, 8000 Bahía Blanca, Argentina.
2 CONICET (Consejo Nacional de Investigaciones Científicas y Técnicas),
8000 Bahía Blanca, Argentina.
3 CIC (Comisión de Investigaciones Científicas de la Provincia
de Buenos Aires), 1900 La Plata, Argentina.
Key words: Algarrobo de Chile, In vitro culture, Prosopis chilensis, regeneration, rooting.
ABSTRACT:
Prosopis chilensis (Mol.) Stuntz (Algarrobo de Chile) is an important native
tree species that can be grown in arid and semiarid regions for wood and
forage production and environmental protection. Developing a simple and
reliable in vitro protocol for cloning it would enable to improve it genetically.
Explants of P.chilensis were taken from 4 months-old plants grown in the
greenhouse or from adult trees grown in a natural environment. Nodal segments
1 – 2 cm long containing an axillary bud were selected from elongating
shoots. These cuttings were aseptically cultured on two agar-solid basal
media, MS or BTMm, and treated with 0.05 mg L-1 BA and 3 mg L-1 of either
IAA, IBA or NAA. Sucrose (3% w/v) was used as carbon source. The percentage
of sprouted cuttings and whole plant regeneration as well as its shoot and
root length were recorded. Number, length and dry weight of shoots and roots
were also measured. Rooting was successful with cuttings taken from young
or adult plants, but explants from young plants showed a better response.
Culturing in BTMm resulted in significantly greater shoot and root biomass
than culturing in MS. Moreover,
this response was higher in young explants when IBA was used as growth regulator.
This paper reports a simple and effective method to micropropagate P. chilensis
from young and adult plants.
ABBREVIATIONS: BA: Benzyl Adenine; BTMm: Broadleaf Tree Medium modified; MS: Murashigue and Skoog Medium; IAA: Indole-3-Acetic Acid; IBA: Indole-3-Butyric Acid; NAA: a-Naphthalene-acetic Acid.
Perdigon
ADJUVANT EFFECTS OF Lactobacillus casei ADDED TO A RENUTRITION DIET IN A
MALNOURISHED MOUSE MODEL
PAOLA GAUFFIN CANO1, GRACIELA AGÜERO3 AND GABRIELA
PERDIGON1,2
1. Centro de Referencias para Lactobacilos (CERELA). Chacabuco 145 (4000).
Tucumán. Argentina.
2. Cátedra de Inmunología, Instituto de Microbiología.
Facultad de Bioquímica, Química y Farmacia. Universidad Nacional
de Tucumán.
3. Cátedra de Análisis Clínico, Instituto de Bioquímica
Aplicada. Facultad de Bioquímica, Química y Farmacia. Universidad
Nacional de Tucumán.
Key words: malnutrition, Lactobacillus casei, mucosal immunity, gut barrier, renutrition diet.
ABSTRACT:
Nutritional deficiencies are associated with impaired immune response, affecting
the body’s defence mechanisms. It is also known that Lactic Acid Bacteria
(LAB) and fermented products such us yogurt have immunopotentiator activity
and nutritional properties, and could thus be used as a valuable supplement
in a renutrition diet. The aim of this study was to determine, in a non-severe
malnutrition model, the effective dose of Lactobacillus casei (L.casei),
which when is used as an adjuvant in a renutrition diet, would modulate
the mucosal immune system and induce recovery of the integrity of the intestinal
barrier. The experiments were performed on groups of malnourished and renourished
BALB/c mice. They received after milk renutrition a supplement of different
doses and periods of L. casei feeding. We measured body
weight; hematologic values and serum proteins. We also characterized small
intestine immunoglobulin secreting cells, intraepithelial leukocytes, mastocytes
and goblet cells. Structural and ultrastructural studies were performed.
Our results suggest that impaired gut barrier and mucosal immune function
produced by malnutrition can be reversed by L. casei and that the dose of
107 cfu/day/mouse administered during 5 consecutive days was the optimal
one for recovery of the gut mucosal immune system. The clinical significance
of these findings suggests ways for improving mucosal immunity, and generating
protection against enteropathogens in hosts immunosuppressed by malnutrition.
PROLACTIN-RELEASING
ACTIVITY OF GHRP-5 (MOMANY PEPTIDE) ON LACTOTROPHS IN VIVO AND IN VITRO
ANA LUCÍA DE PAUL*, MÓNICA BONATERRA*,
CLAUDIA GABRIELA PELLIZAS**,
AGUSTÍN AOKI* AND ALICIA INÉS TORRES*
* Centro de Microscopía Electrónica. Facultad de Ciencias
Médicas.
** Departamento de Bioquímica Clínica, Facultad de Ciencias
Químicas. Universidad Nacional de Córdoba. RA 5000. CC362.
Córdoba, República Argentina.
Key words: PRL secretion, GHRP-5, lactotroph, immunocytochemistry, mRNA PRL.
ABSTRACT: In the present study the in vivo and in vitro effects of GHRP-5 on the PRL-releasing activity in correlation with the morphological changes of lactotroph cells and their transcriptional activity were evaluated. The in vivo treatment (12 mg/100g BW/day for 3 days) of male rats with GHRP-5 does not induce any significant changes in serum PRL levels. In contrast, the addition of GHRP-5 to pituitary cell cultures increased significantly the release of PRL. This effect is enhanced in cell cultures of enriched lactotrophs, increasing significantly the secretion of PRL, the concentrations of which were 50% higher than that of untreated control cells. The administration of GHRP-5 provokes several changes in the fine structure of lactotrophs, compatible with an increased secretory activity. After the GHRP-5 treatment the different lactotroph subtypes persist but the subtype I displaying secretory granules of larger size (500-900nm) and a significant development of the Golgi apparatus and RER were more frequently observed. These results can be correlated with a significant augmentation in PRL mRNA after the GHRP-5 treatment. In spite of that no variations in serum PRL levels were observed in vivo, following GHRP-5 treatment, the lactotroph population experienced evident fine structure modifications, concordant with an upsurge of PRL synthesis. These observations confirmed a direct action of GHRP-5 on receptors expressed by lactotrophs. The differential actions of GHRP-5 on in vivo and in vitro designs confirm a different effectiveness of this secretagogue to induce PRL secretion.
CHANGES
OF INDUCIBLE NITRIC OXIDE SYNTHASE IN AORTIC CELLS DURING THE DEVELOPMENT
OF HYPERTENSION: EFFECT OF ANGIOTENSIN II
MONTSERRAT CRUZADO, CLAUDIA CASTRO, NORMA RISLER AND ROBERTO MIATELLO
Cell Culture Laboratory, Departments of Morfophysiology and Pathology. School
of Medicine. National University of Cuyo (UNC).
Key words: hypertension, inducible nitric oxide synthase, angiotensin II, spontaneously hypertensive rats, vascular smooth muscle cells.
ABSTRACT: Nitric oxide (NO) generation by inducible nitric oxide synthase (iNOS) in the vascular smooth muscle cells (VSMC), may play a role in blood vessel tone regulation. Lipopolysaccharide (LPS) induced iNOS activity and subsequent nitrite production by cultured aortic VSMC, from SHR with an established chronic blood pressure elevation (adult SHR) or during the period preceding the development of hypertension (young SHR) and from age-matched normotensive Wistar (W) rats were compared. Angiotensin II (Ang II) effect was also evaluated. Both basal LPS-induced iNOS activity and nitrite accumulation were significantly lower in young SHR VSMC compared to young W rat cells. In contrast, adult hypertensive and normotensive rat cells did not differ in NO generation. Besides, young SHR cells exhibited a significant smaller iNOS activity and nitrites than adult SHR cells. After 24h-incubation with Ang II, both variables were markedly reduced in all groups. The proportional reduction of iNOS activity and nitrites by Ang II was not different between hypertensive and normotensive rat cells, at any age. However, this Ang II inhibitory effect was greater in both adult SHR and W cells than in VSMC from young rats. In conclusion, a reduced LPS-induced iNOS activity and NO generation was observed in VSMC form spontaneously hypertensive rats before the raise of blood pressure, but not in adult hypertensive rat cells. Additionally, an inhibitory effect of angiotensin II on these variables is described. We can speculate that the impairment in vascular smooth muscle NO production precedes the development of hypertension in SHR and may play a pathophysiologic role in the early blood pressure elevation in genetically hypertensive rats.
Workshop: Biology of Ampullariidae
Minireview
OLD
SPECIES AND NEW CONCEPTS IN THE TAXONOMY OF Pomacea (GASTROPODA: AMPULLARIIDAE)
NÉSTOR J. CAZZANIGA
Departamento de Biología, Bioquímica
y Farmacia, Universidad Nacional del Sur. San Juan 670, (8000) Bahía
Blanca, Argentina.
Key words: Apple snails, Pomacea canaliculata, South America, Species concepts, Taxonomic procedures.
ABSTRACT:
The taxonomic history of the South American genus Pomacea Perry, 1810, and
some shifts of systematic concepts during recent decades are briefly reviewed.
Too many pre-evolutionist, shell-defined species created a gibberish, the
only acceptable solution of which being perhaps a conventional, somewhat
authoritarian decision based on expertise. The addition of other sources
of morphological, biochemical, ecological or genetic information should
not solve the problem if it is not accompanied by a sound reappraisal of
the species concepts. Since the assumptions of each concept differ, any
correspondence between them is irrelevant, and may drive to incompatible
results. The shell variability of Pomacea canaliculata was acknowledged
for most authors throughout more than a century. A recent insight into its
life-history traits demonstrated they are as variable as the morphology.
These findings stress the need of determining the ecological identity of
any pest apple-snail population at a local scale, because its invading ability
may be not exactly correlated to its taxonomical identity. Probably, all
the canaliculata-like apple snails constitute a single, very variable “species”
in most senses, even though different subsets may be recognized under other
incommensurable concepts.