Sex Differences in Internalizing Symptoms and Amygdala Functional Connectivity in Neurotypical Youth

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Internalizing symptoms in neurotypical youth relate to amygdala connectivity.

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Greater modulation is observed in females than in males.

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Connectivity might be a symptom of or a risk factor for disorders.

Amygdala resting-state functional connectivity (rsFC) is altered in adolescents with internalizing disorders, though the relationship between rsFC and subclinical symptomatology in neurotypical youth remains unclear. Here we examined whether amygdala rsFC varied across a continuum of internalizing symptoms in 110 typically-developing (TD) youths 8 to 17 years old using functional magnetic resonance imaging (fMRI). We assessed overall internalizing symptoms, as well as anxious-depressed, withdrawn-depressed, and somatic complaints. Given known sex differences in the prevalence of internalizing disorders, we compared connectivity between males and females. As compared to males, females with greater internalizing, anxious-depressed, and somatic symptoms displayed greater connectivity with the cingulate gyrus, insula, and somatosensory cortices. In contrast, males with greater anxious-depressed symptoms demonstrated weaker connectivity with the subcallosal prefrontal cortex. Sex differences in rsFC in relation to symptom severity were evident for the whole amygdala and for two of its subnuclei (centromedial and superficial amygdala). Overall, results suggest that, for females, higher internalizing symptoms are associated with greater rsFC between the amygdala and regions implicated in emotional and somatosensory processing, salience detection, and action selection. Future longitudinal investigations are needed to determine whether this hyperconnectivity may confer resilience to, or pose risk for, the development of internalizing disorders.

Relationships among filamentous microorganisms in rotating biological contactors

The existing relationships were studied among the different types of filamentous microorganisms that appear in the biofilm of a biological contactor system. Using the hierarchical cluster analysis it was observed that, in all the stages, Beggiatoa sp. and the Eikelboom's types 0803 and 1863 always appeared associated, while Sphaerotilus natans was always associated with the morphological type 021N. The remaining microorganisms were associated in variable forms in the plants. In addition, different association models were obtained according to the season of the year and the stage-season interaction. It has also been observed that a significant correlation exists among the filamentous microorganisms we have studied and the different physical-chemical parameters.

Cytosolic glutamine synthetase and not nitrate reductase from the green alga Chlamydomonas reinhardtii is phosphorylated and binds 14-3-3 proteins

The nitrate reductase activity from Chlamydomonas reinhardtii was not altered when extracts were incubated with yeast 14-3-3 proteins in the presence of Mg-ATP. However, the C. reinhardtii extracts contained 14-3-3 proteins capable of inhibiting the spinach nitrate reductase, raising the question of their physiological substrates. Two C. reinhardtii proteins of about 48 and 35 kDa were eluted from 14-3-3 affinity chromatography columns and bound to 14-3-3s in overlay assays. The 48-kDa protein corresponded to the cytosolic isoform of glutamine synthetase (GS1). The GSI was phosphorylated by a Ca2+-and calmodulin-dependent protein kinase partially purified from the alga. However, neither phosphorylation nor 14-3-3 binding seemed to change GS catalytic activity.

[Pyogenic liver abscess as a complication of Crohn's disease]

Pyogenic liver abscess in patients with Crohn's disease is not common, but the mortality has been reported to be high if diagnosis and treatment is delayed. Intra-abdominal abscesses, fistulous disease, and steroid therapy have all been reported to be important predisposing factors in the pathogenesis of this entity. We present a patient with Crohn's disease in whom multiple abscesses were encountered in the right lobe of the liver. The diagnosis of liver abscess was established by abdominal computed tomography and the patient was treated by percutaneous catheter drainage. Awareness of this rare complication is important because diagnosis is difficult to make and a high index of suspicion is required. Once suspected, aggressive diagnostic workup and treatment is indicated. Most patients with liver abscess can be successfully managed by percutaneous catheter drainage combined with antibiotic therapy if it is diagnosed before extensive necrosis has occurred.

Seasonal changes in peripheral blood leukocyte functions of the turtle Mauremys caspica and their relationship with corticosterone, 17-beta-estradiol and testosterone serum levels

We have studied the most representative functions of lymphocytes such as adherence to substrate, mobility directed to a chemoattractant gradient (chemotaxis), proliferative response to mitogens and antibody-dependent cellular cytotoxicity (ADCC), as well as natural killer (NK) activity in peripheral blood cells from the turtle Mauremys caspica, and the seasonal changes of these functions in both female and male animals. The plasma levels of steroid hormones were determined to study their relationship with the immune functions. Our results show high chemotaxis, lymphoproliferative response and ADCC as well as NK activity in winter when the levels of corticosterone, testosterone and 17-beta-estradiol were depleted. Proliferative responses to phytohaemagglutinin (PHA), concanavalin A (Con A) and pokeweed mitogen (PWM) were increased in spring correlating with low levels of corticosterone and testosterone in middle and late spring. In summer, the proliferative response was decreased but adherence, chemotaxis, ADCC and NK activity were increased, although steroid hormones showed high plasma levels. In autumn, a depletion of both the hormone levels and the immune response were found except for adherence to substrate. The immune functions studied were strikingly influenced by the seasonal cycle, which induced a different pattern of response depending on the function analyzed. Moreover, these immune cells showed a different degree of dependence on steroids in relation to the function and the season considered, suggesting the existence of other factors that modulate the immune response studied.

The Chlamydomonas reinhardtii Nar1 gene encodes a chloroplast membrane protein involved in nitrite transport

A key step for nitrate assimilation in photosynthetic eukaryotes occurs within chloroplasts, where nitrite is reduced to ammonium, which is incorporated into carbon skeletons. The Nar1 gene from Chlamydomonas reinhardtii is clustered with five other genes for nitrate assimilation, all of them regulated by nitrate. Sequence analysis of genomic DNA and cDNA of Nar1 and comparative studies of strains having or lacking Nar1 have been performed. The deduced amino acid sequence indicates that Nar1 encodes a chloroplast membrane protein with substantial identity to putative formate and nitrite transporters in bacteria. Use of antibodies against NAR1 has corroborated its location in the plastidic membrane. Characterization of strains having or lacking this gene suggests that NAR1 is involved in nitrite transport in plastids, which is critical for cell survival under limiting nitrate conditions, and controls the amount of nitrate incorporated by the cells under limiting CO(2) conditions.

The negative effect of nitrate on gametogenesis is independent of nitrate assimilation in Chlamydomonas reinhardtii

The effect of nitrate on gamete differentiation as well as on the expression of genes involved in gametogenesis, nitrogen scavenging, and nitrate assimilation has been analyzed in wild-type and mutant strains of Chlamydomonas reinhardtii. Nitrate prevented gamete formation from wild-type strains and caused a strong reduction in the number of zygotes recovered in genetic crosses between nitrate-assimilation-deficient mutants, thus suggesting that nitrate by itself is providing a negative regulatory signal for the sexual differentiation of the alga. Addition of nitrate at low concentrations to wild-type cells, after an initial period of nitrogen starvation, resulted in a drastic decrease in transcript levels of both nitrate-assimilation genes (NIA1 and NRT2;1) and genes induced after N-starvation (NCG2 and NCG4). This strong effect of nitrate was due to its assimilation products since it was not evident in nitrate-assimilation mutants. A slight negative effect of nitrate on NCG4 expression was only observed in the mutant. Nitrate by itself was also found to provide a negative signal for the expression of gamete-specific genes (GAS3 and GAS18) in mutants incapable of assimilating nitrate.

A high affinity nitrate transport system from Chlamydomonas requires two gene products

A nitrate-regulated cluster of genes involved in nitrate transport and assimilation has been identified in Chlamydomonas reinhardtii. Mutant strains of the alga, which are defective in some aspect of transport and assimilation have been used to assign functions to these genes. This analysis has suggested that two gene products are necessary to obtain a functional high affinity nitrate system in Chlamydomonas [Quesada et al. (1994) Plant J. 5, 407-419]. In this paper we have tested this hypothesis by injecting Xenopus oocytes with mRNA prepared from these two cDNAs, Nrt2;1 and Nar2, and then assaying the oocytes for nitrate transport activity. Oocytes injected with single types of mRNA did not show any nitrate transport activity. Furthermore, Nar2 mRNA was toxic to oocytes, with nearly 60%, of the oocytes dead 3 days after the injection. However, when oocytes were injected with a mixture of two mRNAs prepared from Nrt2;1 and Nar2, a high affinity nitrate transport activity could be measured. However, the Km for nitrate of this transport system was 28 microM which is higher than the value of 1.6 microM which had been obtained by the analysis of mutant phenotypes. The pH-dependence of the nitrate-elicited currents was consistent with a proton-cotransport mechanism. These results prove that two gene products are required to produce a functional high affinity nitrate transport system and that this process does not involve transcriptional regulation.

Nitrite reductase mutants as an approach to understanding nitrate assimilation in Chlamydomonas reinhardtii

We constructed mutant strains lacking the nitrite reductase (NR) gene in Chlamydomonas reinhardtii. Two types of NR mutants were obtained, which either have or lack the high-affinity nitrate transporter (Nrt2;1, Nrt2;2, and Nar2) genes. None of these mutants overexpressed nitrate assimilation gene transcripts nor NR activity in nitrogen-free medium, in contrast to NR mutants. This finding confirms the previous role proposed for NR on its own regulation (autoregulation) and on the other genes for nitrate assimilation in C. reinhardtii. In addition, the NR mutants were used to study nitrate transporters from nitrite excretion. At high CO(2), only strains carrying the above high-affinity nitrate transporter genes excreted stoichiometric amounts of nitrite from 100 microM nitrate in the medium. A double mutant, deficient in both the high-affinity nitrate transporter genes and NR, excreted nitrite at high CO(2) only when nitrate was present at mM concentrations. This suggests that there exists a low-affinity nitrate transporter that might correspond to the nitrate/nitrite transport system III. Moreover, under low CO(2) conditions, the double mutant excreted nitrite from nitrate at micromolar concentrations by a transporter with the properties of the nitrate/nitrite transport system IV.

Differential regulation of the high affinity nitrite transport systems III and IV in Chlamydomonas reinhardtii

Two high affinity nitrite transporters have been identified in Chlamydomonas reinhardtii. They have been named system III and system IV and shown to be differentially regulated by nitrogen and carbon supply. System III was induced under high CO(2) and required a micromolar nitrate signal for optimal expression, was inhibited by ammonium, and was not affected by either chloride or the chloride channel inhibitor 5-nitro-2-(3-phenylpropylamino)benzoic acid. System IV was induced optimally under limiting CO(2) and did not require nitrate signal, was inhibited by chloride and 5-nitro-2-(3-phenylpropylamino)benzoic acid, but was not affected by ammonium. Two transcripts that shared the expression pattern of systems III and IV activities were detected with an Nrt2;3 gene probe. In addition, a mutant defective in both the activity of system III and the expression of Nrt2;3 gene has been isolated. Genetic crosses and in vivo complementation studies indicate that this mutant is defective in a locus that is closely linked to the regulatory gene Nit2.

Parenteral infusions bacterial contamination in a multi-institutional survey in Mexico: considerations for nosocomial mortality

BACKGROUND

Parenteral infusions can be contaminated during administration (extrinsic contamination). A previous survey found that extrinsic contamination was not uncommon in a hospital in Mexico with lapses in aseptic techniques. To determine whether this problem exists in other similar institutions, we undertook a multi-institutional study.

METHODS

We surveyed 6 hospitals (A to F) lacking an infection control committee to determine the level of extrinsic contamination. We visited each hospital and obtained samples of all the parenteral infusions in use, drawing 0.5-1 mL from the tubing injection port. Quantitative and qualitative bacterial cultures were performed. Chlorine levels of the tap water were measured. Visits were repeated until the survey was completed.

RESULTS

A total of 751 infusions were cultured, of which 16 (2.13%) were contaminated. Hospital contamination rates varied from zero to 5.56%. Klebsiella pneumoniae was the most common isolate (10 cases). During the first sampling day in hospital C, the 7 infusions from the pediatric ward were found to be contaminated with a similar K pneumoniae strain. In-service education was started in this hospital. Infusion contamination was eliminated followed by a reduction in mortality rate. Overall, a higher risk for infusion contamination was noted for pediatric patients (P =.01, odds ratio = 3.28, 95% CI, 1.10-9.91) and in wards with inadequate water chlorine levels (P =. 02, odds ratio = 3.64, 95% CI, 1.08-13.51).

CONCLUSIONS

If the hospitals surveyed are representative of others in developing countries, an endemic level of parenteral infusion contamination could exist in many hospitals throughout the world.

Antigen recognition characteristics and comparative performance in immunoaffinity purification of two monoclonal antibodies specific for the hepatitis B virus surface antigen

In this paper we describe the antigen recognition characteristics, variable region base and amino acid sequence, and performance as immunoaffinity chromatography ligands of two MAb specific to the alpha determinant of the HBsAg, derived from the same fusion. We show that the epitope recognized by CB-Hep.0 (IgM) is probably associated to an intrachain disulfide bond in the antigen. On the other hand, CB-Hep.1 (IgG2b) recognizes a heat-resistant non-conformation dependent antigenic determinant on HBsAg. PCR-cloning and sequencing of the variable regions of these two MAb indicated that both heavy chain variable regions were originated from the usage of the same germinal V and J genes. However, the outstanding differences in the size of the VH CDR3, and the absolute difference in the light chain sequences, suggest that the hybridomas were originated from different precursor B lymphocytes. With respect to their use as immunoaffinity chromatography ligands for the purification of a recombinant HBsAg, we found that the IgM immunogel exhibited increased performance with respect to amount of eluted antigen, and final recovery. This difference in overall performance could be attributed to a series of factors: the higher valence number of IgM, a dissimilar distribution of IgM and IgG in the activated gel particles, and differences in antigen recognition between both MAb. Our results suggest that IgM antibodies may be useful in immunopurification, particularly if the antigen is structurally complex and has a high density of repeating epitopes.

Effects of prenatal protein malnutrition on hippocampal CA1 pyramidal cells in rats of four age groups

The present study was undertaken to investigate the effect of prenatal protein deprivation on area CA1 hippocampal pyramidal cells on postnatal (P) days 15, 30, 90 and 220 using Golgi techniques. Age related changes in both groups and diet related changes between groups were assessed. There were significant diet effects at all four ages, with one of 12 different measurements showing a significant diet effect on P15, five on P30, one on P90, and seven on P220. The most marked effect of the diet was on pyramidal cell dendrite spine density in the stratum moleculare and stratum radiatum, with a different pattern of diet effects in the two strata. In pyramidal cell dendrites in the stratum moleculare, there was a deficit in spine density that was significant at three of the four ages and there were similar age-related changes in the two diet groups. Spines on pyramidal cell dendrites in the stratum radiatum showed a lack of synchrony of age-related changes in the two diet groups, with an increased spine density in the malnourished rats on P30 and a widening deficit in this parameter on P90 and P220. The bimodal distribution to these changes, with most marked deficits occurring on P30 and P220, with an intervening period of apparent "catch-up" on P90, is of interest and may be a significant brain adaptation to malnutrition. The present study is the final of three morphometric studies on the effect of prenatal protein restriction on three key neurons in the hippocampal trisynaptic circuit. When compared to our previous studies on the dentate granule cell and the CA3 pyramidal cell, it is noted that there is an effect of the low protein diet on all these neurons, with the most marked effect on the predominantly postnatally generated dentate granule cells.

Isolation and characterization of two new negative regulatory mutants for nitrate assimilation in Chlamydomonas reinhardtii obtained by insertional mutagenesis

Plasmid DNA carrying either the nitrate reductase (NR) gene or the argininosuccinate lyase gene as selectable markers and the corresponding Chlamydomonas reinhardtii mutants as recipient strains have been used to isolate regulatory mutants for nitrate assimilation by insertional mutagenesis. Identification of putative regulatory mutants was based on their chlorate sensitivity in the presence of ammonium. Among 8975 transformants, two mutants, N1 and T1, were obtained. Genetic characterization of these mutants indicated that they carry recessive mutations at two different loci, named Nrg1 and Nrg2. The mutation in N1 was shown to be linked to the plasmid insertion. Two copies of the nitrate reductase plasmid, one of them truncated, were inserted in the N1 genome in inverse orientation. In addition to the chlorate sensitivity phenotype in the presence of ammonium, these mutants expressed NR, nitrite reductase and nitrate transport activities in ammonium-nitrate media. Kinetic constants for ammonium (I4C-methylammonium) transport, as well as enzymatic activities related to the ammonium-regulated metabolic pathway for xanthine utilization, were not affected in these strains. The data strongly suggest that Nrg1 and Nrg2 are regulatory genes which specifically mediate the negative control exerted by ammonium on the nitrate assimilation pathway in C. reinhardtii.

Nitrate and nitrate are transported by different specific transport systems and by a bispecific transporter in Chlamydomonas reinhardtii

Nitrate transport mutants from Chlamydomonas reinhardtii and strains derived from them upon transformation with plasmids containing the C. reinhardtii nar2/Nrt2;1 or nar2/Nrt2;2 genes have been used to study nitrate and nitrite transport systems. Mutants lacking nitrate assimilation clustered genes showed a high affinity nitrite transporter activity (system 3), which was subject to ammonium inhibition and appeared to be independent of a functional nar2 gene. Transformants carrying nar2/Nrt2;2 recovered a high affinity nitrate transporter activity (system 2) and showed nitrite transport activities with properties similar to those in nonrecovered high affinity nitrate transporter activity (system 1) together with a considerably enhanced nitrite transport activity. Nitrite transport mediated by system 1 was very sensitive to inhibition by nitrate at microM concentrations. Results strongly suggest that three nitrate assimilation related high affinity transport systems operate in C. reinhardtii: one specific for nitrite, a second one encoded by nar2/Nrt2;2 specific for nitrate, and another one encoded by nar2/Nrt2;1, which is bispecific for these two anions.

Retinal vasculitis associated with Crohn's disease

Although systemic vasculitis can be a complication of inflammatory bowel disease at several locations (skin, eyes, brain, mesentery, and lung) the association of retinal vasculitis with Crohn's disease is rare. We studied a 26-year-old woman with biopsy-demonstrated Crohn's disease who developed a severe bilateral retinal arteritis and phlebitis, with acute loss of vision.

Identification of nitrate transporter genes in Chlamydomonas reinhardtii

The Chlamydomonas reinhardtii nar-2, nar-3, and nar-4 genes, which are within a nitrate-regulated gene cluster containing the nitrate reductase structural gene nit-1, have been related to nitrate transport. Mutant strains defective in nitrate transport and having an active nitrate reductase have been genetically constructed. Their nitrate non-utilizing phenotype has been directly complemented by transformation using the pCO-5 plasmid which carries the nar-2, nar-3, and nar-4 clustered genes. Integration of pCO-5 DNA in the genome of nitrate transport mutants resulted in the expression of these nar transcripts and the recovery of a high affinity nitrate transport activity. Complementation of the nitrate non-utilizing phenotype of the constructed strains was also achieved by co-transformation with plasmids containing nar-2 and nar-3 genes or nar-2 and nar-4, but not with single plasmids containing each individual gene. In addition, DNA sequences of a practically complete cDNA of nar-3 and a partial one of nar-4 have been generated and the deduced amino acid sequences showed a very significant identity with that of the nitrate transporter gene (crnA) from Aspergillus nidulans. These data strongly support the hypothesis that the nitrate transport system in C. reinhardtii contains at least two protein components encoded by the nar-2 and nar-3 genes. The nar-4 gene would produce a protein with a high identity to that of nar-3.

Protein malnutrition on suprachiasmatic nucleus cells in rats of three ages

The effects of prenatal and postnatal protein malnutrition on the major and minor somatic axes of the suprachiasmatic nucleus (SCN) cells of the rat were investigated. Female rats were fed either 6%, 8% or 25% casein diet 5 weeks before mating, during gestation and lactation. After weaning the pups were maintained on the same diet until sacrifice at 30, 90 or 220 days of age. The major and minor axes in fusiform, multipolar and ovoid cells were measured in Nissl-stained SCN slices. Although the 8% diet group displayed significant reductions in fusiform and ovoid cells, the 6% diet group showed the most intense reductions in cell size of the three cell types. In the 6% diet group, cell size was significantly lower at 30 days but the difference with the other nutritional groups ameliorated at 90 days and almost reached control values at 220 days. These data suggest that malnutrition maintained during gestation and postnatal life reduces the somatic size of SCN cells. This alteration may be a morphological substrate underlying sleep and behavioral circadian alterations observed in malnourished rats.

Five nitrate assimilation-related loci are clustered in Chlamydomonas reinhardtii

Three overlapping clones covering a Chlamydomonas reinhardtii genomic region of about 32 kb appear to contain five genes potentially involved in nitrate assimilation in addition to the nitrate reductase structural locus nit-1. These new loci produced transcripts of 2.8, 2.2, 1.8 and 1.7 kb in nitrate-induced wild-type cells that, like the 3.4 kb transcript of nit-1, were undetectable in cells grown in ammonium. In addition, in a mutant defective at the regulatory locus, nit-2 for nitrate assimilation, which does not express the nit-1 gene transcript, accumulation of the four other transcripts was also blocked. They have been named nar (nitrate assimilation related) genes. The nar-1 and nar-2 loci are transcribed in the same orientation as nit-1. The nar-3 and nar-4 loci are transcribed divergently from nit-1. DNA and RNA sequences from both nar-3 and nar-4 cross-hybridized with each other indicating that they share similar sequences. Four nitrate assimilation-deficient mutants (C2, D2, F6 and G1) were characterized. These mutants lack nar transcripts and have major deletions and/or rearrangements in the nar gene cluster. In contrast to other nitrate reductase-deficient mutants and to wild type, deletion mutants and the regulatory mutant nit-2 were incapable of accumulating intracellular nitrate. Two of the mutants in which expression of all the nar loci did not occur, C2 and D2, grew in nitrite medium and showed wild-type levels of both nitrite uptake and nitrite reductase activities.(ABSTRACT TRUNCATED AT 250 WORDS)

Nitrate Reductase Regulates Expression of Nitrite Uptake and Nitrite Reductase Activities in Chlamydomonas reinhardtii

In Chlamydomonas reinhardtii mutants defective at the structural locus for nitrate reductase (nit-1) or at loci for biosynthesis of the molybdopterin cofactor (nit-3, nit-4, or nit-5 and nit-6), both nitrite uptake and nitrite reductase activities were repressed in ammonium-grown cells and expressed at high amounts in nitrogen-free media or in media containing nitrate or nitrite. In contrast, wild-type cells required nitrate induction for expression of high levels of both activities. In mutants defective at the regulatory locus for nitrate reductase (nit-2), very low levels of nitrite uptake and nitrite reductase activities were expressed even in the presence of nitrate or nitrite. Both restoration of nitrate reductase activity in mutants defective at nit-1, nit-3, and nit-4 by isolating diploid strains among them and transformation of a structural mutant upon integration of the wild-type nit-1 gene gave rise to the wild-type expression pattern for nitrite uptake and nitrite reductase activities. Conversely, inactivation of nitrate reductase by tungstate treatment in nitrate, nitrite, or nitrogen-free media made wild-type cells respond like nitrate reductase-deficient mutants with respect to the expression of nitrite uptake and nitrite reductase activities. Our results indicate that nit-2 is a regulatory locus for both the nitrite uptake system and nitrite reductase, and that the nitrate reductase enzyme plays an important role in the regulation of the expression of both enzyme activities.

Ultrastructure of natural and induced myxospores of Archangium gephyra

The ultrastructure of natural myxospores and glycerol-induced myxospores has been studied in four Archangium gephyra strains (AG3, AG5, AG9, and AG10). The induced myxospores show an oval shape, characteristic of the genus Archangium, and an electron-dense coat surrounds the cell wall. The cytoplasm contains abundant electron-lucent inclusions. Sometimes, a membranous structure appears between the coat and the outer membrane. The fruiting-body myxospores show an oval shape similar to that observed in induced myxospores, but with a slightly thicker outer coat. In many of the natural myxospores, some membranous, lamellar or vesicular structures appear. They are located between the coat and the outer membrane, resembling those that appeared in induced myxospores. These have not been previously mentioned in papers on fruiting-body myxospores. These structures occasionally seem to be fused, giving rise to membranous sacs filled with an amorphous material of medium electron density. We propose that these vesicles are formed from the waved outer membrane and from the fruiting-body matrix. Large, dense, fusiform inclusions with an internal crystalline array are frequently found in the cytoplasm of natural myxospores, and cells during differentiation, in strains AG3, AG9, and AG10. Key words: Archangium gephyra, electron microscopy, myxospores, ultrastructure.

Effects of prenatal protein deprivation on postnatal development of granule cells in the fascia dentata

The effect of prenatal protein deprivation on the postnatal development of granule cells in the fascia dentata in the rat was studied at 15, 30, 90, and 220 days of age. The granule cells showed a significant reduction in cell size, decreased number of synaptic spines throughout their dendritic extent, and reduced complexity of dendritic branching in the outer two-thirds of the molecular layer. All of these deficits were present at 15 days and persisted throughout the study (220 days). The least deficits in synaptic spine density occurred at 90 days and in dendritic branching at 30 days. Partial restitution of earlier, more severe deficits was associated primarily with maturational events occurring in the protein deprived rats, whereas later increases in deficits were related primarily to a failure of the protein deprived rats to keep pace with neuronal development occurring in the controls. The present results are similar to those noted in our previous study in this journal of the effect of a low protein diet (8% casein) on these neurons that extended from pregnancy until the time of sacrifice at 30, 90, and 220 days of age (Cintra et al., '90; 532:271-277). Taken together, these two studies suggest that the postnatal adaptation of the granule cells to prenatal protein deprivation is primarily due to events that occur during pregnancy and that the site of predilection for the deficit is their dendrites in the outer two-thirds of the molecular layer of the fascia dentata.

Regulation of nitrite uptake and nitrite reductase expression in Chlamydomonas reinhardtii

Expression of nitrite uptake and nitrite reductase activities has been studied in Chlamydomonas reinhardtii under different nutritional conditions. Both activities were expressed at a low level in derepressed cells (with no nitrogen source) and at a high level in induced cells (with nitrate or nitrite). Nitrate was required for both activities to be maximally expressed. Ammonium-grown cells did not show nitrite uptake capability and had a basal nitrite reductase activity. Nitrite uptake but not nitrite reductase levels decreased very significantly in nitrate-induced cells subject to cycloheximide treatment, which suggests that protein(s) involved in the uptake are under a rapid turnover. Nitrite uptake expression was strongly inhibited by the presence of the glutamine synthetase inhibitor L-methionine-D,L-sulfoximine under either derepression or induction conditions, whereas that of nitrite reductase was not affected under the same conditions. Our results indicate that nitrite uptake expression is regulated primarily by ammonium, and that of nitrite reductase by both ammonium and ammonium derivative(s).

Effects of protein undernutrition on the dentate gyrus in rats of three age groups

The effect of an 8% casein and a control 25% casein diet on the granule cells in the dorsal blade of the dentate gyrus of the rat hippocampal formation was studied at 30, 90 and 220 days of age. Female rats were fed either an 8% or 25% casein diet 5 weeks prior to conception and the litters were maintained on these respective diets until killed. In rapid-Golgi-impregnated cells, we measured major and minor axes of the soma of the dentate granule neurons, the number of spines on 50-microns segments of proximal, middle and terminal regions of the largest dendrite per granule cell and the number of dendrites intersecting 8 concentric rings 38 microns apart. At all 3 ages studied undernourished rats showed, when compared to controls, significant reductions of the major and minor axes of the somata and significant reductions in the number of spines on dendrites in the middle and terminal dendritic segments. Dendritic branching was significantly reduced in undernourished rats compared to controls in all but the 4th concentric rings, with the greatest effect being seen on the outer 3 concentric rings at 90 and 220 days of age. The location of the deficit in dendritic synaptic spines and the greatest deficit in dendritic branching correspond to the sites of termination of the lateral and medial perforant pathway projection to the dentate gyrus on the terminal and middle dendritic segments of the granule cells. The deficits noted in the granule cells of the dentate gyrus in this study were more severe than those found in our previous studies on the effect of the low protein diet in these same rats on visual cortical pyramidal cells and on the 3 cell types in the nucleus raphe dorsalis and nucleus locus coeruleus.

Impaired calcium sequestration activity in liver microsomes from fasted rats

Calcium uptake activity was assayed in liver microsomal vesicles from fed and fasted rats. This activity required ATP and was stimulated by the calcium trapping agent oxalate. The most striking feature was the low rate of calcium accumulation in liver microsomes from fasted rats. Maximal rate was inhibited up to 66 and 82% after 1 and 3 days starvation, respectively. This defective microsomal calcium handling suggests its possible involvement in the massive glycogen breakdown during starvation.

Stimulation by calcium and carbamoylcholine of the ouabain-sensitive uptake of 86Rb+ in isolated rat pancreatic acinar cells

The uptake of 86Rb+ was assayed in isolated rat pancreatic acinar cells to determine the effect of calcium and carbamoylcholine on the ouabain-sensitive and ouabain-insensitive components. The presence of calcium in the medium bathing the cells during the preincubation and the main incubation periods was needed to preserve in optimum conditions the uptake of 86Rb+, the stimulation by carbamoylcholine and the sensitivity to ouabain. In the presence of calcium, the ouabain-sensitive component of 86Rb+ uptake was higher than the ouabain-insensitive. The ouabain-sensitive component was 3-times lower in cells incubated in a medium lacking calcium and containing 1 mM EGTA, as compared to cells incubated in the presence of calcium. Carbamoylcholine, at 5 X 10(-4) M, stimulated the uptake of 86Rb+ and this effect depended on the presence of calcium in the bathing medium. Maximal stimulation by carbamoylcholine was reached at 0.2 mM calcium. The nett stimulation by carbamoylcholine was inhibited up to 85% by 1 mM ouabain. As judged by digitonin-disruption of plasma membrane, the above-indicated effects were limited to a cytoplasmic pool of 86Rb+ and a leaky plasma membrane could be ruled out. The results suggest that in rat pancreatic acinar cells, carbamoylcholine stimulated the ouabain-sensitive uptake of 86Rb+ and required the presence of calcium in the bathing medium.

Compartmentation of calcium in digitonin-disrupted guinea pig pancreatic acinar cells

The treatment of guinea pig pancreatic acinar cells with digitonin leads to disruption of the plasma membrane, as judged by the liberation of cytosolic enzymes, without significant alteration of the mitochondrial membrane. The transport of calcium by the particulate residue was studied, and two different pools could be distinguished. One was supported by ATP or ADP, succinate providing the respiratory substrate, and was sensitive to the inhibitors, Ruthenium red and azide. The other pool needed the presence of ATP, ADP being ineffective, and also was unaffected by Ruthenium red or by azide, but was stimulated several-fold by oxalate. The Ruthenium red-sensitive calcium pool has characteristics resembling those of the transport of calcium by a mitochondrial fraction prepared from digitonin-treated acinar cells. In contrast, the Ruthenium red-insensitive calcium transport has characteristics resembling those of a microsomal fraction obtained from guinea pig pancreas. When the transport of calcium in digitonized cells was assayed at a calcium concentration range of 10(-8)-10(-4) M, preferential Ruthenium red-insensitive calcium transport could be observed at submicromolar calcium concentrations.

Effects of oxaloacetate and beta-hydroxybutyrate on rat liver mitochondrial calcium flow during starvation

Rat liver mitochondria accumulate calcium from the incubation medium both in the presence of ATP and of succinate with rotenone. Lowering free calcium concentration by means of EGTA leads to a reduction of maximum transport capacity to less than 25% of the total added calcium. Under these conditions addition of oxaloacetate inhibits calcium uptake, an effect which is blocked by equimolar concentrations of beta-hydroxybutyrate. Oxaloacetate and acetoacetate induce an efflux of previously accumulated mitochondrial calcium. These effects appear to be independent of free calcium concentration and of whether the mitochondria were obtained from fed rats or rats fasted for 16 h or 4 days.