Proliferative opisthomastigote forms in Herpetomonas roitmani (Kinetoplastida: Trypanosomatidae)

The flagellate Herpetomonas roitmani is a symbiont-bearing trypanosomatid that spontaneously differentiates from promastigote to para- and opisthomastigote forms when maintained in axenic culture medium. Thus, after cultivation for 72 h at 28 degrees C, 37% of the total number of cells are in the opisthomastigote form. In the present study, light microscopy observations of Giemsastained H. roitmani cells demonstrated that in early cultures (12 h at 28 degrees C) the percentage of opisthomastigotes was markedly high (about 98%). Furthermore, proliferative opisthomastigote forms (dividing cells with the kinetoplast posteriorly located relative to the nucleus) were frequently seen in these cultures. The latter observation was confirmed by analysis of routinely fixed parasites by transmission electron microscopy.

Trophoendodermal stem cell-derived extracellular matrices: absence of detectable entactin and presence of multiple laminin species

Extracellular matrices (ECM) generated by trophoendodermal stem cells transplanted into the peritoneum of host rats were investigated. Two types of trophoendodermal transplants were studied: (1) free-floating cystic structures, and (2) solid masses adherent to various abdominal organs. Trophoendodermal stem cell ECM obtained from either transplant source was dominated by the presence of laminin similar to Engelbreth-Holm-Swarm (EHS) tumour ECM. However, in contrast to EHS tumour ECM, another ECM component, entactin, was below the level of detection in trophoendodermal stem cell ECM. The laminins present in the two types of trophoendodermal stem cell transplants exhibited distinct differences. Tissues used as sources of one type of laminin were devoid of the other type of laminin. The two species of rat laminin behaved similarly on sodium dodecyl sulphate-polyacrylamide gels and had virtually identical amino acid compositions. The laminins also had similar cruciform patterns when examined by rotary shadowing. Rat laminins differed in their binding to an ion exchange resin: laminin isolated from peritoneal cysts bound to the resin (acidic laminin); laminin isolated from solid masses failed to bind (basic laminin). Acidic rat laminin showed reduced capacity to form laminin-laminin associations when compared with basic rat laminin. Acidic/soluble laminin proved to be a useful reagent in the development of a radio-immunoassay for laminin. Laminin concentrations in the peritoneal fluid of transplant-bearing rats was very high (approximately 400 micrograms/ml) and entirely of the acidic/soluble form. In summary, trophoendodermal stem cell ECM possesses a distinct composition with a lack of detectable entactin, and trophoendodermal stem cells are capable of modulating the characteristics of laminin, depending upon their organization. These features of trophoendodermal stem cell ECM may represent signals responsible for at least some of the unique features of the trophoendodermal stem cell transplants.

Analysis of cytochrome P-450 side-chain cleavage gene promoter activation during trophoblast cell differentiation

Trophoblast giant cell differentiation is accompanied by transcriptional activation of the cytochrome P-450 side-chain cleavage (P450scc) gene. The Rcho-1 trophoblast cell line has the capacity to differentiate along the trophoblast giant cell lineage and has been used to study trophoblast-specific P450scc gene expression. In this report, P450scc gene promoter activities in trophoblast-specific P450scc gene expression. In this report, P450scc gene promoter activities in trophoblast cells have been mapped and the involvement of known modulators of steroid hydroxylase gene expression, the cyclic AMP/protein kinase A pathway and steroidogenic factor-1 (SF-1), evaluated. Comparisons were made with Y-1 adrenal and R2C Leydig cells. The cumulative results from transient and stable transfection experiments implicate the region between -428 and -511 bp of 5'-flanking DNA in the developmental activation of the P450scc promoter during trophoblast giant cell differentiation. Differences in basal activities of the P450scc promoter constructs were also observed in Y-1 adrenal and R2C Leydig cells; however, the magnitude of the differences was modest. Activators of the protein kinase A pathway stimulated P450scc promoter activity in Y-1 cells, whereas similar treatment of Rcho-1 trophoblast cells did not stimulate but actually inhibited P450scc promoter activity. The inhibitory activity was localized between -639 and -894 bp of the P450scc promoter. SF-1 mRNA and protein were detected in adrenal and gonadal cells but not in rat placenta or Rcho-1 trophoblast cells by Northern and Western blotting, respectively. Thus, P450scc gene activation during trophoblast cell differentiation involves an 83-bp region of its 5'-flanking DNA between -428 and -511 but does not appear to involve cyclic AMP-activated pathways or SF-1. In conclusion, the mechanism of P450scc gene activation during trophoblast cell differentiation appears different from the regulation of P450scc gene activation in other steroidogenic tissues.

Effects of temperature on promastigotes of several species of Leishmania

Six Leishmania species were studied comparatively, in order to determine the influence of temperature "in vitro" on differentiation, infectivity and protein synthesis. Differentiation occurred in a heterogeneous manner, even in species that produce similar clinical manifestations. Thus, no association could be found between thermosensitivity and disease. The association between expression of proteins and increasing temperatures was analyzed at 34 degrees C by polyacrylamide gel electrophoresis with sodium dodecyl sulphate (SDS-PAGE), using different incubation times, and employing a technique involving metabolic incorporation of [35S]-methionine. Protein synthesis was very similar in all the New World species apart from L. amazonensis, which expressed a protein of approximately 80 kDa when incubated at 34 degrees C for 2 hours. All the tested species had in common the expression of a 70 kDa protein. Differences, however, were observed in relation to the time interval for protein expression. In L. chagasi, synthesis was detected after 30 minutes of incubation at 34 degrees C, while L. braziliensis required 1 hour at the same temperature. The "in vivo" and "in vitro" infectivity of the differentiated forms was also analyzed, but no significant differences were observed.

[The developmental cycle of Rhodnius nasutus Stal, 1859 studied in the laboratory]

The biological cycle of Rhodnius nasutus was studied from november 1985 to September 1986 under laboratory conditions. The temperature ranged from 28.0 +/- 2 degrees C to 22.0 +/- 2 degrees C and 59.2 to 70.4% of humidity. Chickens were used as a blood meal source. The complete biological cycle was achieved with an average of 209.4 days of the 16 remaining insects from initial colony of the 30 Katomines. The average incubation period lasted 11.1 days and those for the following nymphal stages were: 17.6 days for the first; 16.1 days for the second; 30.1 days for the third; 71.2 days for the fourth and 79.9 days for the fifth nymphal stage.

The Golgi complex of Trypanosoma cruzi epimastigote forms

The distribution and morphology of the Golgi complex and endoplasmic reticulum of epimastigote forms of the protozoan Trypanosoma cruzi were analysed at the ultrastructural level, after post-fixation of the cells with osmium tetroxide/potassium iodide. Intense staining was found in these structures, as well as in the nuclear envelope, showing that these compartments present a reducing environment. Positive reaction also demonstrates that intense protein synthesis occurs in the parasites which were collected at the log phase of growth. A Cis Golgi network (CGN) and an endoplasmic reticulum cistern associated with it could be clearly demonstrated. Different Golgi complex patterns were seen, suggesting that this organelle has a dynamic structure. In most cells, only peripheral cisternae directed to the endoplasmic reticulum presented an electron-dense reaction product, possibly corresponding to the cis region of the Golgi complex. Some parasites were also incubated in the presence of brefeldin-A, a drug which disorganizes the Golgi complex of several eukaryotic cells. Our results showed that T. cruzi epimastigote forms are resistant to brefeldin-A treatment, suggesting that the targets of drug action are absent in these protozoa.

Regulation of deoxyribonucleic acid synthesis in proliferating and differentiating trophoblast cells: involvement of transferrin, transforming growth factor-beta, and tyrosine kinases

This report investigates the regulation of DNA synthesis in trophoblast stem cells and differentiating trophoblast cells. Experiments in this study were performed on the Rcho-1 trophoblast cell line, which was established from a transplantable rat choriocarcinoma. Rcho-1 trophoblast cells can be manipulated to proliferate or differentiate along the trophoblast giant cell pathway. DNA synthesis in quiescent trophoblast stem cells (maintained in serum-free medium) was stimulated by fetal bovine serum and donor horse serum or transferrin to a level approximately 30- and 10-fold above the basal level, respectively. Transferrin and horse serum were ineffective at maintaining trophoblast cell proliferation. In contrast, serum-starved differentiating trophoblast cells synthesize DNA at maximal levels and could not be further stimulated by the addition of exogenous factors. Fetal bovine serum-stimulated proliferation was effectively inhibited by transforming growth factor-beta 1. Experiments with the tyrosine kinase inhibitor genistein implicate tyrosine kinase involvement in the regulation of DNA synthesis and proliferation in trophoblast stem cells and DNA synthesis in differentiating trophoblast cells. Proliferating and differentiating trophoblast cells differ in their levels of tyrosine kinase activities and express unique tyrosine-phosphorylated proteins. In summary, DNA synthesis and proliferation in trophoblast stem cells are under extrinsic control, whereas DNA synthesis in differentiating trophoblast cells is under intrinsic control. Both mechanisms require tyrosine kinase activity, but the nature of the tyrosine kinase pathways in each process appears to be distinct.

Co-localization of placental lactogen-I, placental lactogen-II, and proliferin in the mouse placenta at midpregnancy

This study was undertaken to determine whether mouse placental lactogen (mPL)-I, mPL-II, and proliferin (PLF) are expressed by the same population of placental giant cells at midpregnancy. Tissue sections from Day 9 of pregnancy were analyzed by double immunofluorescence staining. Sections were stained for PLF by use of a rhodamine-conjugated second antibody, and for mPL-I or mPL-II by use of a fluorescein-conjugated second antibody. All three proteins were present in most of the same giant cells. The distribution of mPL-I and PLF among giant cells in vitro was also examined. When placental cells from Day 7 of pregnancy were cultured for 5 days, > 90% of the cells that immunostained for mPL-I also immunostained for PLF on the first 3 days of culture. Thereafter, the percentage of cells that contained both proteins declined rapidly while the percentage that contained only PLF increased, suggesting continued differentiation of the cells in vitro. These data demonstrate that the same trophoblast giant cells express mPL-I, mPL-II, and PLF simultaneously at midpregnancy, suggesting that their gestational profiles in maternal blood during this period result at least partly from changes in gene expression in one population of cells and not from differentiation of several subsets of giant cells, each expressing only one member of the gene family.

Expression of decidual prolactin-related protein in the rat decidua

It is well established that rat decidual tissue produces a PRL-like hormone(s) that binds to the PRL receptor on both the corpus luteum and the decidual cells and initiates profound changes in the endocrine milieu required for the establishment of pregnancy. The recent cloning of a decidual PRL-related protein (dPRP) prompted us 1) to determine whether the expression of this gene is triggered by decidualization of the endometrial stromal cells, 2) to examine the temporal and cell-specific pattern of its expression, and 3) to examine the role of both decidual signals and PRL on levels of its messenger RNA (mRNA). Total RNA was isolated from uteri of either nonpseudopregnant rats or pseudopregnant rats with or without decidual tissue. A 1-kilobase mRNA species hybridizing strongly with the dPRP probe was present in decidualized uteri. No dPRP mRNA could be detected in uteri not subjected to decidualization. Developmental studies indicated a constant high level of dPRP mRNA in the decidual tissue until day 12 of pseudopregnancy, followed by a marked decline at a time when extensive cell death occurs in the decidua, suggesting that dPRP is constitutively expressed in this tissue. To examine the cell-specific expression of dPRP, antimesometrial decidua was separated from mesometrial decidua, and the large antimesometrial cell population was separated from the small mesometrial cells by elutriation. The results of Northern analysis revealed clearly that dPRP is abundantly and solely expressed in the large antimesometrial cells. No dPRP mRNA could be detected in the mesometrial cells and in numerous other endocrine and nonendocrine tissues. A faint signal was observed, however, in the trophoblast. Despite the very strong paracrine regulation between the antimesometrial and mesometrial cells and the high levels of PRL receptor expression in these cells, both in vivo and coculture experiments revealed no regulation of dPRP gene expression by either PRL or mesometrial cell signal, adding further support to the possibility that once induced, dPRP remains constitutively expressed. In summary, the results of this investigation revealed that the expression of dPRP in endometrial stromal cells is triggered by the induction of decidualization and that this gene is selectively and abundantly expressed in a defined cell population located in the anti-mesometrial region of the uterus. Thus, dPRP is not only a useful indicator of decidualization, but is also an excellent marker for the differentiated antimesometrial cells.

Differential responses of phenotypically distinct rat trophoblast cell lines to MHC class I antigen-inducing cytokines

Phenotypically distinct rat trophoblast cell lines, the Rcho-1 and R8RP.3 cells, were compared for their responses to cytokines known to induce major histocompatibility (MHC) class I antigens, tumour necrosis factor (TNF), transforming growth factor-beta (TGF-beta), and interferon-gamma (IFN-gamma). Cell enzyme immunosorbent assays and flow cytometry experiments showed that only IFN-gamma could induce RT1 class I antigens on the Rcho-1 cells. Non-adherent cells were slightly less responsive than adherent, giant cell-like Rcho-1 cells. By contrast, RT1 class I antigens on the R8RP.3 cells were induced by both TGF-beta 1 and IFN-gamma. The cytokines also had different effects on mitochondrial enzyme activity in the two lines. TNF and TGF-beta 1 mRNAs were demonstrated in both lines by using Northern blot hybridization. Rcho-1 but not R8RP.3 cells contained two TNF messages (approximately 2.2, 1.9 kb). Steady state levels of transcripts from the TNF gene, and, to a lesser extent, the TGF-beta 1 gene, were increased in cultures of Rcho-1 cells that contained high proportions of giant cells. Thus, phenotypically distinct rat trophoblast cell lines do not respond identically to TNF, TGF-beta 1 or IFN-gamma, transcription of cytokine genes does not prevent the cells from responding to paracrine cytokine signals, and the cells contain novel TNF transcripts that might be important in cell maturation or differentiation.

Recapitulation of the pathway for trophoblast giant cell differentiation in vitro: stage-specific expression of members of the prolactin gene family

The trophoblast giant cell lineage is characterized by endoreduplication and expression of members of the PRL gene family. This report describes the functional consequences following in vitro manipulation of a rat trophoblast cell line, termed Rcho-1. Rcho-1 cells can be cultured under conditions that promote proliferation or differentiation. Proliferation is maintained by culturing the cells in the presence of fetal bovine serum under subconfluent conditions. Differentiation is induced by growing the cells to confluence and removing the mitogenic source. Differentiation is characterized by continued synthesis of DNA in the absence of proliferation (endoreduplication) and the sequential expression of members of the PRL gene family. Western and Northern blot analyses demonstrated that placental lactogen-I (PL-I) was first expressed, followed sequentially by PL-II, PRL-like protein-A, and PRL-like protein-C. The ontogeny of expression of members of the PRL gene family by the Rcho-1 cells recapitulated the pattern of in situ expression by trophoblast giant cells of the junctional zone of the chorioallantoic placenta. A notable difference between in vivo trophoblast giant cell differentiation and in vitro Rcho-1 cell differentiation is the termination of PL-I expression in normal trophoblast giant cells developing in vivo and the continued expression of PL-I in differentiated Rcho-1 cell cultures. The Rcho-1 cell line provides a unique in vitro model for investigating the initiation and maintenance of the trophoblast giant cell differentiation pathway.

Spontaneous differentiation of trophoblast cells along the spongiotrophoblast cell pathway: expression of members of the placental prolactin gene family and modulation by retinoic acid

The purpose of this study was to examine part of the trophoblast cell multilineage pathway and its modulation by retinoic acid. A method for studying trophoblast cell differentiation along the spongiotrophoblast cell pathway in vitro was established and characterized. Cells were isolated from junctional zones of Day 13 rat chorioallantoic placentas via mechanical dissection, enzymatic digestion, and enrichment through a Percoll cushion. The cells were cultured up to 8 days and analyzed for their purity, morphology, and ability to express members of the placental prolactin (PRL) family. Cell preparations contained minimal mesenchymal contamination as estimated by immunocytochemical analysis for vimentin. The cells expressed PRL-like protein-A (PLP-A), PLP-B, PLP-C, and placental lactogen-I variant (PL-Iv) indicative of their differentiated spongiotrophoblast cell phenotype. Expression of members of the PRL family increased markedly during culture. Temporally the increase in PLP-A expression preceded the increased expression of PLP-B (0.9 kb), PLP-C, and PL-Iv. These in vitro observations paralleled the behavior of spongiotrophoblast cells developing in situ. Some differences were evident, including the immediate activation of PLP-B (1.2 kb) following enzymatic isolation of the cells. These cells were also susceptible to experimental manipulation. Exposure to retinoic acid influenced the morphology of the cells and the profile of members of the placental PRL family expressed by in vitro differentiated cells. In summary, a culture system has been devised to examine the control of spongiotrophoblast cell differentiation and the regulation of expression of members of the placental PRL gene family. Spongiotrophoblast cells spontaneously differentiate in vitro through discrete developmental phases that are susceptible to modulation by retinoic acid.

Whole body protein turnover in chronically undernourished individuals

1. Two groups of adult men were studied in Bangalore, India, under identical conditions: the 'normal weight' subjects (mean body mass index 20.8 kg/m2) were medical students of the institute with access to habitual energy and protein intakes ad libitum. The other group, designated 'undernourished', were labourers on daily wages (mean body mass index 16.7 kg/m2). 2. In an earlier study we obtained lower absolute values for both basal metabolic rate and protein synthesis in the undernourished subjects; however, when the data were expressed on a body weight or fat-free mass basis, a trend towards higher rates of protein synthesis, as well as higher basal metabolic rate, was evident. The suggestion was made that such results reflected the relatively higher energy intakes per kg body weight of the undernourished subjects on the day of study. The objective of the present study was therefore to control for the dietary intake during the measurement of whole body protein turnover. 3. In the present study dietary intakes were equated on a body weight basis; however, expressed per kg fat-free mass, the normal weight subjects had received marginally higher intakes of energy and protein. The results, however, were similar to those of the previous study. In absolute terms, basal metabolic rate, protein synthesis and breakdown were lower in the undernourished subjects. When expressed per kg body weight or per kg fat-free mass, the undernourished subjects had higher basal metabolic rates than the well-nourished subjects, whereas no differences were seen in the rate of protein synthesis or breakdown.(ABSTRACT TRUNCATED AT 250 WORDS)

Proteinase activities during temperature-induced stage differentiation of species complexes of Leishmania

We have examined by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), using gelatin, bovine serum albumin (BSA) or human IgG as substrate, proteinase activities in cell lysates from selected species complexes of Leishmania. The inhibition of proteinase activity caused by the reagent L-trans-epoxysuccinylleucylamido(4-guanidino)butane (E-64), which is known to act only on cysteinyl proteinases, revealed a 31 kDa component of this class of enzymes in soluble, but not in membrane-enriched preparations, of either L. amazonensis or L. major-like parasites from the New World. The proteinase component was detectable in the leishmanial multiplicative promastigote stage (log phase) and its concentration apparently increased during the thermally induced transformation of promastigotes to amastigote-like forms in vitro. Comparative studies revealed that taxonomically distinct species complexes of Leishmania possess high amastigote cysteine proteinase activity. This feature, however, was lacking in other developmental stages of the species (L. braziliensis, L. chagasi, L. aethiopica, and L. donovani) analyzed. Furthermore, lesion amastigotes of L. amazonensis displayed ultrastructurally recognizable megasomes, but megasome-like or large multivesicular body organelles could be detected only in axenic amastigotes of both L. amazonensis and L. major-like species.

Transcriptional activation of cytochrome P450 side chain cleavage enzyme expression during trophoblast cell differentiation

The purpose of this study was to investigate P450scc expression during trophoblast differentiation. Biochemical characteristics of P450scc protein and mRNA identified in rat trophoblast tissues were similar to those identified in the rat adrenal gland. Furthermore, P450scc was localized to trophoblast giant cells. This observation prompted an examination of progesterone biosynthesis and P450scc expression in Rcho-1 cells. Rcho-1 cells were derived from a transplantable rat choriocarcinoma, their differentiation can be regulated, and they have the capacity to express the trophoblast giant cell phenotype. Progesterone was produced by Rcho-1 cells and increased approximately 100-fold as the cells progressed from proliferation to differentiation. P450scc protein and mRNA accumulation also increased during trophoblast differentiation. P450scc expression within the Rcho-1 cell line was restricted to trophoblast giant cells. To further investigate the regulation of P450scc expression during trophoblast differentiation, we examined a plasmid construct, containing 894 base pairs of DNA 5' upstream from the P450scc transcriptional start site linked to a human growth hormone reporter gene, following stable transfection into Rcho-1 cells. The transfected P450scc regulatory DNA permitted the expression of human growth hormone which paralleled expression of the endogenous P450scc gene. In conclusion, transcriptional activation of the P450scc gene accompanies trophoblast giant cell differentiation.

Membrane-associated polysaccharides composition, nutritional requirements and cell differentiation in Herpetomonas roitmani: influence of the endosymbiont

Herpetomonas roitmani, a trypanosomatid containing a bacterial endosymbiont, was cured by high doses of chloramphenicol. Wild-type and cured flagellates were compared as to polysaccharide composition, nutritional requirements and cellular differentiation. Fucose (18.0%), xylose (15.7%), mannose (38.9%), galactose (10.8%), glucose (16.4%) and inositol (< 1.0%) were identified as polysaccharide components of cured H. roitmani as assessed by gas-liquid chromatography. However, the wild-type strain displayed a markedly different sugar profile, in that xylose was absent and inositol preferentially synthesized, whereas the other monosaccharide components remained unchanged. Variations in nutritional pattern also occurred between both strains. The bacterial endosymbiont seems to provide the flagellates with nutritional factors, including usual amino acids, vitamins, purine (as adenine) and hemin. The process of cell differentiation was also significantly influenced by the endosymbiont. Opisthomastigote forms predominate (72.0%) in cured as compared with wild-type H. roitmani (37.0%).

The reservosomes of epimastigote forms of Trypanosoma cruzi: occurrence during in vitro cultivation

Reservosomes are large membrane-bound structures found mainly at the posterior end of epimastigote forms of Trypanosoma cruzi, the agent of Chagas' disease. We screened 5-day-old culture forms of the following strains at the ultrastructural level for the presence of reservosomes: T. cruzi strains Y and YuYu as well as Trypanosoma (Schizotrypanum) spp. strains M431, M504, and M519 isolated from bats (Epitesicus sp.) in Santa Catarina, Brazil. The organelles could be found in all strains analyzed, supporting a previous hypothesis that they are a marker of trypanosomes of the Schizotrypanum subgenus. Stereological analysis was carried out with the Y strain to follow the development of reservosomes and lipid droplets during in vitro cultivation of the parasites. Reservosomes were partitioned to the daughter cells during cell division such that the organelles were present in newly formed parasites. Estimation of the volume density after 3, 5, 7, 9, and 12 days of cultivation showed that it was lower in younger cultures, becoming maximal at day 9 (8.0%), but decreased in older cultures (5.9% at day 12). Morphological changes also occurred: type I reservosomes presented an electron-dense matrix with lipid droplets and were characteristic of younger cultures, whereas type II reservosomes presented a homogeneous matrix without lipid inclusions and predominated in older cultures. These organelles were absent in bloodstream trypomastigote forms isolated from infected mice.(ABSTRACT TRUNCATED AT 250 WORDS)

Molecular cloning and sequence analysis of two porcine seminal proteins, PSP-I and PSP-II: new members of the spermadhesin family

Two full-length cDNAs encoding porcine seminal proteins, PSP-I and PSP-II, have been isolated from a porcine seminal vesicle cDNA library. Nucleotide sequence analysis of the 706-bp PSP-I cDNA predicts a precursor protein of 133 amino acid residues, which includes a 21-residue signal peptide and a 112-residue secreted protein. On the other hand, the complete sequence of the 686-bp PSP-II cDNA reveals a coding sequence for a 21-residue signal peptide and a 116-residue secreted protein. The predicted amino acid sequences agree very well with those determined by conventional amino acid sequence analysis. Alignment of the two cDNA sequences shows an overall 66% sequence homology throughout their entire length. However, the sequence homology is much higher in the 3' untranslated region (72%) than in the coding region (61%). This suggests that these two genes evolved by duplication and divergence from a common ancestral gene. They share about 50% amino acid sequence homology and a similar overall structure with three members of the spermadhesin family.

Trophoblast cell differentiation and organization: role of fetal and ovarian signals

The rat chorioallantoic placenta is organized into two distinct zones (junctional and labyrinth) and expresses six members of the placental prolactin (PRL) family: placental lactogen-I (PL-I), PL-I variant (PL-Iv), PL-II, PRL-like protein-A (PLP-A), PLP-B, and PLP-C. These placental hormones are expressed in distinct cell- and temporal-specific patterns and can be used to monitor the state of differentiation of rat trophoblast cells. This study was initiated to examine the role of the fetus and maternal ovaries in the regulation of trophoblast cell differentiation and organization. Expression of the placental PRL family was monitored by Northern and Western blotting and immunocytochemical analysis. The roles of the fetus and maternal ovaries were examined by chemically induced fetal death (DFX, induced by intraamniotic injection of digoxin) and surgical removal of the ovaries (OVX), respectively. The endocrine differentiation of the placenta was assessed on day 19 of gestation (sperm positive = day 0, parturition = day 21). Day 10 of gestation was the earliest day that DFX could be reliably performed. Day 10 is a time point during pregnancy preceding the onset of expression of all members of the placental PRL family except PL-I. DFX on day 10 of gestation did not affect the endocrine differentiation of the trophoblast cells but did alter the organization of the chorioallantoic placenta. PL-II, PL-Iv, and the PLPs were all expressed in their appropriate molecular forms and cell types in placentas developing in the absence of fetal influence. The maternal ovaries, in the absence of the fetus, had two distinct actions on the placenta: ovarian signals were essential during a period at midgestation for the maintenance of the placenta and exposure of the developing placenta to ovarian signals during the second half of gestation, in the absence of the fetus, arrested labyrinth zone development. The active ovarian signals were progesterone and estrogen. We conclude that trophoblast cell differentiation occurs independent of the fetus and maternal ovaries. However, signals from both the fetus and maternal ovaries are required for normal organization of the chorioallantoic placenta.

A factor(s) from a trophoblast cell line increases tyrosine hydroxylase activity in fetal hypothalamic cell cultures

We previously reported that a factor(s) from rat choriocarcinoma (Rcho-1) cells suppresses circulating PRL levels and increases tyrosine hydroxylase activity in tuberoinfundibular dopaminergic neurons in vivo. The purposes of this study were to determine whether this factor(s) increases tyrosine hydroxylase activity in fetal hypothalamic cells in vitro and to evaluate its chemical nature. The Rcho-1 cells are of placental origin and have the capacity to differentiate into giant cells and produce members of the placental PRL family. MMQ cells, a pituitary cell line that secretes PRL, and HRP-1, a placental cell line that does not produce any known members of the PRL family, were used as control cells. Tyrosine hydroxylase activity was assessed by incubation of hypothalamic cells for 1 h with 100 microM brocresine, an inhibitor of aromatic L-amino acid decarboxylase. Tyrosine hydroxylase activity was increased in a density-dependent manner when Rcho-1, but not HRP-1 or MMQ, cells were cocultured with hypothalamic cells for 24 h. Control and Rcho-1-stimulated tyrosine hydroxylase activities were markedly reduced with 1 mM alpha-methyl-p-tyrosine, a specific inhibitor of tyrosine hydroxylase. Tyrosine hydroxylase activity was not altered when hypothalamic cells were incubated for 24 h with rat PRL or recombinant rat placental lactogen-I, whereas a 24-h stimulation with 100,000 Rcho-1 cells and a 1-h stimulation with 5 mM (Bu)2cAMP increased tyrosine hydroxylase activity 3.7- and 3-fold, respectively. The magnitudes of the increase in tyrosine hydroxylase activity were similar when hypothalamic cells were cocultured with Rcho-1 cells for 1 and 24 h. Acetic acid extracts of Rcho-1, but not HRP-1 or MMQ, cells increased tyrosine hydroxylase activity within 1 h in a concentration-dependent manner. The 3-fold increase in tyrosine hydroxylase activity observed with 500,000 Rcho-1 cell equivalents was markedly reduced with 1 mM alpha-methyl-p-tyrosine. The mol wt range of the tyrosine hydroxylase-activating factor(s) (THAF) was estimated using ultrafiltration membranes. The majority of activity was found in the eluate from a 1,000 mol wt cut-off membrane. THAF activity in Rcho-1 cell extracts was decreased by preincubation with pronase, a nonspecific proteolytic enzyme, suggesting that the factor(s) is a peptide. THAF was resistant to inactivation by trypsin or chymotrypsin pretreatment. However, both enzymes destroyed the ability of pituitary adenylate cyclase-activating peptide, either alone or with Rcho-1 cell extracts, to increase tyrosine hydroxylase activity. Oxidation of Rcho-1 cell extracts with performic acid abolished THAF activity.(ABSTRACT TRUNCATED AT 400 WORDS)

Binding characteristics and immunolocalization of porcine seminal protein, PSP-I

PSP-I, a 13 kDa protein purified from boar seminal plasma, was found to have about 50% amino acid sequence homology with a family of zona pellucida-binding proteins known as spermadhesins. These proteins are produced by the accessory gland(s) of the male reproductive tract and coat the spermatozoa during ejaculation. In this study, we have investigated the possible biological functions of PSP-I using a solid-phase protein binding assay and its site of synthesis using both Western blot and immunocytochemical analyses. PSP-I was found to bind a number of proteins including endo-beta-galactosidase digested ZP3, soybean trypsin inhibitor, IgA, IgG and alpha-casein, indicating that it may have multiple functions. The protein or carbohydrate structures were not critical in the binding, since polyvinyl sulfate could effectively inhibit the binding of PSP-I to these proteins. Western blot analysis using specific antiserum to PSP-I showed that the protein was present in the seminal vesicle but not in the testes, epididymis or prostate. The protein was revealed by immunocytochemical analysis in the epithelium of seminal vesicles but not in the testes or the epididymis. It is concluded that PSP-I is synthesized by the epithelium of the seminal vesicles, secreted into the semen during ejaculation, and may be involved in various reproductive functions, such as preventing premature acrosome reaction and immunosuppression.

Intracellular lectin-binding sites in symbiont-bearing Crithidia species

Crithidia oncopelti, C. deanei, and C. desouzai are flagellates of the Trypanosomatidae family that present bacterium-like endosymbionts in their cytoplasm. Direct and indirect lectin-gold labeling techniques were used at the electron microscopic level in Lowicryl K4M-embedded cells to demonstrate the presence of intracellular lectin-binding sites. We used the lectins Ulex europaeus I, Griffonia simplicifolia II, Ricinus communis I, Arachis hypogaea, G. simplicifolia I, Wistaria floribunda, Limulus polyphemus, and Canavalia ensiformis, which recognize alpha-L-fucose, alpha- and beta-N-acetylglucosamine, beta-galactose and beta-N-acetylgalactosamine, beta-galactose, alpha-galactose, beta-N-acetylgalactosamine, sialic acid and alpha-D-mannose, and alpha-D-glucose residues, respectively. The nucleus was the cellular structure most frequently labeled by the lectins. The Golgi complex was seldom labeled, whereas the endoplasmic reticulum and the flagellar pocket presented a large number of binding sites. Symbionts had their two unit membranes weakly labeled by the different lectins but displayed no labeling of the space between the membranes.

Predictive equations for basal metabolic rates of Indian males

The article deals with the generation of a prediction equation for basal metabolic rate (BMR) of well-nourished Indian males, from prospective measurements on 121 males, using a single validated technique. The equation related BMR to simple measures such as weight (WT) and age, and was given by: BMR (kJ/d) = 48.7 * WT-14.1 * AGE + 3599. The equation was internally as well as externally validated against other Indian databases and the net differences of < 2% (100 kJ/d), were non-significant. Interestingly, American BMRs were predicted to within 0.5% (28 kJ/d) by this equation, while European BMRs were significantly higher than predicted by 6.3% (433 kJ/d). Similar results were obtained on validating the American and European data against the equations of C. K. J. Henry & D. G. Rees (1991) Eur J. Clin. Nutr. 45, 177-185. Such results suggest that there are no differences in the BMR of age- and weight-matched Asian Indian males, other tropical populations and Americans. This has implications in the estimation of energy expenditure and hence energy requirements for these populations.

The effect of exercise on the riboflavin status of adult men

Six sedentary to moderately active men with biochemical signs of riboflavin deficiency were studied under metabolic ward conditions to examine the effects of physical activity on riboflavin status. All participants were subjected to additional exercise (EXER) for an 18 d period between two maintenance (M1 and M2) periods (16 and 13 d respectively) of habitual physical activity. Energy balance and riboflavin intake were maintained throughout the study. Riboflavin status, as judged by a significant reduction in erythrocyte glutathione reductase (EC 1.6.4.2) activation coefficient (EGR-AC), improved on changing from home (1.53 (SD 0.14)) to period M1 (1.36 (SD 0.21)) diets. The exercise period, however, resulted in a significant deterioration in riboflavin status (1.57 (SD 0.31)) which persisted in the subsequent period M2 (1.54 (SD 0.15)). There was a concomitant fall in the urinary excretion of riboflavin only in the EXER period, when results were expressed as a percentage of the dietary intake of riboflavin. These results suggest an increased demand for the vitamin for selective biochemical functions during exercise. However, the energy cost of walking (treadmill 4 km/h), 50 W and 100 W work-loads (bicycle ergometer) as well as delta mechanical efficiency (DME) did not change during the three metabolic periods. The urinary excretion of riboflavin was inversely related to DME (r -0.49; P < 0.05) and directly correlated with haemoglobin levels (r 0.63; P < 0.005). The present study suggests that riboflavin status further deteriorates during a short period of increased physical activity in individuals whose riboflavin status is marginal.

Heterologous expression and characterization of prolactin-like protein-A. Identification of serum binding proteins

In this report, we describe the heterologous expression of prolactin-like protein-A (PLP-A) in Chinese hamster ovary (CHO) cells, the characterization of recombinant PLP-A, and the identification of serum PLP-A-binding proteins. CHO cell and native placental PLP-A showed similar immunoreactive characteristics and electrophoretic mobilities. N-terminal sequencing verified the identity and purity of the recombinant PLP-A species and the site of cleavage of the signal peptide from the mature secreted PLP-A species. Recombinant PLP-A lacked activity in standardized prolactin and growth hormone in vitro bioassays. Antibodies generated to recombinant PLP-A facilitated the cellular localization of PLP-A and the identification of high molecular weight PLP-A complexes. Cross-linking analyses of radioiodinated PLP-A with serum harvested from late gestation rats indicated the presence of two major cross-linked complexes migrating under reducing conditions at 130 and 250 kDa and two minor cross-linked complexes migrating at 70 and 110 kDa. Binding of PLP-A to serum proteins was specific for PLP-A and not effectively competed by other members of the prolactin/growth hormone family. The PLP-A binding species were also found in serum from non-pregnant female and male rats.

Decidual prolactin-related protein. Identification, molecular cloning, and characterization

In this report, we describe the isolation, molecular cloning, and characterization of a new member of the prolactin (PRL)-growth hormone (GH) family expressed in rat decidual tissue. A 29-kDa protein was isolated from medium conditioned by decidual explants. The protein possessed an affinity for concanavalin A and cross-reactivity with antibodies to two rat placental proteins, PRL-like protein-B (PLP-B) and PLP-C and with antibodies to human PRL. NH2-terminal sequencing of the isolated decidual protein indicated that it shared significant sequence identity with the NH2 terminus of PLP-C. The decidual protein was termed decidual prolactin-related protein (dPRP). A PLP-C cDNA was used to identify dPRP cDNAs from a rat decidual cDNA library. Nucleotide sequence analyses of the dPRP cDNAs predicted a mature protein of 239 amino acids, including a 28-amino acid signal sequence. The predicted dPRP amino acid sequence contains two putative N-linked glycosylation sites and 6 cysteine residues. The 6 cysteines are located in positions homologous to the cysteines of PLP-C and PRL. Additional sequence similarities with members of the PRL-GH family are evident. The dPRP gene was localized to rat chromosome 17, which also carries other members of the PRL gene family. Northern blot analysis showed that the dPRP cDNA clone specifically hybridized to a 1.0-kilobase mRNA. The relationship of dPRP with other members of the PRL-GH family and its putative role(s) in the physiology of pregnancy are discussed.

Trophoblast-specific transcription from the mouse placental lactogen-I gene promoter

We have isolated the gene encoding mouse placental lactogen-I and characterized the promoter region of this gene by transient and stable transfection. Promoter sequences extending 274 basepairs (bp) up-stream from the start site of transcription contain all of the elements necessary for maximal expression upon transient transfection into the rat choriocarcinoma Rcho-1 cell line; these Rcho-1 cultures contain both proliferative trophoblast stem cells and terminally differentiated trophoblast giant cells. In stably transfected cell lines, expression from this promoter increases as the percentage of differentiated cells in the culture increases. In contrast to these results in trophoblast cells, the 274-bp promoter as well as a promoter region extending 2700 bp up-stream of the transcriptional start site are unable to drive transcription in a variety of other cell types. Mutational and protein binding analyses indicate that two AP-1 sites are required for maximal expression in Rcho-1 cells, and that the composition of the AP-1 transcription factor may vary as differentiation in the cell culture increases. In addition to these two AP-1 sites, at least one other element appears to be critical for promoter activity in trophoblast cells.

A factor(s) from a rat trophoblast cell line inhibits prolactin secretion in vitro and in vivo

The purpose of the present study was to measure the inhibitory action of secretions from trophoblast cells on prolactin (PRL) secretion in cycling and pregnant rats, and to determine whether factor(s) from trophoblast cells act directly on anterior pituitary cells. A rat choriocarcinoma cell line (Rcho)--a line consisting of trophoblast cells, including differentiated giant cells that secrete members of the placental PRL family--was used. When Rcho cells (1 x 10(6) cells) were transplanted under the kidney capsule of cycling rats, tumors developed and the rats went into constant diestrus. Eight days after cell injection, plasma progesterone was significantly increased in treated rats compared to controls, whereas plasma and pituitary PRL and pituitary PRL mRNA levels were significantly decreased. Similar PRL results were seen on Day 9 of pregnancy after injection of Rcho cells on Day 0 or Day 1 of pregnancy. To determine whether secretions from Rcho cells had a direct effect on anterior pituitary cells to inhibit PRL release, anterior pituitary cells were enzymatically dispersed and cultured for 4 days. Conditioned medium was obtained from 9-day Rcho cell cultures and concentrated by ultrafiltration. A fraction containing substances with molecular weights greater than 10,000 suppressed PRL release from the pituitary culture after 3 and 24 h. Conditioned medium containing substances with molecular weights between 1000 and 10,000 had no effect on PRL release, nor did conditioned medium from a placental cell line designated HRP-1. HRP-1 also contains trophoblast cells but does not contain the differentiated giant cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Recombinant porcine prorelaxin produced in Chinese hamster ovary cells is biologically active

Although prorelaxin has a similar structure as proinsulin, the posttranslational processing of prorelaxin seems to be quite different from that of proinsulin. There are no pairs of basic residues flanking the relaxin moiety in most prorelaxins studied so far. Instead, the prorelaxins of many species contains a tetrabasic sequence (Arg-Lys-Lys-Arg) between the connecting peptide and the A-chain. This is the recognition sequence of furin. In order to study this possible processing by furin, we express the recombinant porcine prorelaxin in Chinese hamster ovary cells. The expected 19 kDa recombinant porcine prorelaxin was found to be constitutively secreted into the medium at a level of approximately 250 ng/ml. No conversion of the 19 kDa prorelaxin into the 6 kDa relaxin was observed. Unlike most prohormones which are biologically inactive, the recombinant prorelaxin was found to be biologically active in an in vitro bioassay.

Energy supplementation reverses changes in the basal metabolic rates of chronically undernourished individuals

The objective of the present study was to examine the influence of energy supplementation and its cessation thereafter on the basal metabolic rates (BMR) of chronically undernourished individuals. Seven apparently healthy males were supplemented daily with 3.35 MJ (15 g protein, 35 g fat, 105 g carbohydrate) for 12 weeks. The average gain in body-weight was 1.9 kg (body fat, 58%; fat-free mass (FFM), 42%). The rise in BMR exceeded that accounted for by the increases in FFM during the 12 weeks of supplementation and was attributed to increases in the amount and activity of the visceral tissue as well as to an added cost of lipogenesis. At 12 weeks after cessation of the supplement, body-weights and FFM had decreased to presupplementation levels. BMR at this stage were significantly lower than at the 12th week of supplementation, when expressed per kg FFM or when adjusted for FFM using an analysis of covariance. These results suggest an increase in the metabolic efficiency during this negative energy balance period. The study demonstrates that, in the chronically undernourished, the changes in BMR are reversible and, hence, physiologically important to the process of adaptation to low-energy intakes.

[The functional expectations of valve bioprostheses. I. Physical and histopathological tests for the use of sections of bovine pericardium]

PURPOSE

The heterogenicity of the bovine pericardium sac regarding its elasticity, extensibility and thickness encouraged the work with the purpose to study the different areas of pericardium, mapped according to its position on the heart.

METHOD

Ten bovine pericardium sacs previously selected and obtained at the slaughterhouse immediately after the animal slaughter were utilized. The pericardia were sectioned sagittally from the anterior to the posterior portion, thus obtaining two parts, right and left. Two areas were demarcated for each one of them amounting to four regions: A, B, C and D. Each of the four regions was divided into two regions: 1 and 1, amounting to 80 samples. There have been physical tests (shrinkage and mechanical resistance), histopathological studies and statistical analysis were done.

RESULTS

The right ventricle area (region D) had the best utilization (21.3%), and then the left ventricle area (region B, 16.2%). The physical tests on the utilized samples showed minimum and maximum values of 0.20 and 0.40 mm for the thickness, 2.0 and 7.0 kgf for force, 1.6 and 4.2 kgf/mm2 for rupture, 18 and 36% for stretching, 15 and 65 for tenacity index and 85 and 87 degrees C for shrinkage. The region D presented histologically and more preserved, either for the collagen fibers or the elastic ones.

CONCLUSION

The results of the statistical analysis proved the need to increase the sample size to certify the existence of a sectioning of the pericardium and a more adequate position of the proof body (longitudinal, transversal and oblique) when obtaining the pericardium flap to make the valve bioprosthesis.

A trophoblast-specific factor(s) suppresses circulating prolactin levels and increases tyrosine hydroxylase activity in tuberoinfundibular dopaminergic neurons

Rat choriocarcinoma (Rcho) cells, which are morphologically similar to trophoblast giant cells of the normal placenta and produce placental lactogen-I in vivo, were used to investigate placental feedback on PRL secretion and tuberoinfundibular dopaminergic neuronal activity. Rcho cells were injected into female rats either intracerebroventricularly 60-65 h before use or under the kidney capsule 10-14 days before use. The following endocrine conditions were used: 1) ovariectomized rats with or without bromocriptine treatment, 2) immature (40-44 days old) rats, 3) adult cycling (diestrous) rats, and 4) pregnant rats. Serum PRL levels in ovariectomized, diestrous, and immature female rats were suppressed to less than 20% of control levels by secretions from the Rcho cells. Tyrosine hydroxylase (TH) activity in the stalk-median eminence (SME) was increased 2-fold above control activity in Rcho-treated ovariectomized and immature female rats. When TH activity was reduced to 40% of control levels by 50 h of bromocriptine treatment, secretions from Rcho cells increased TH activity 3.5-fold to levels similar to those for Rcho alone. Even though Rcho treatment suppressed PRL levels, TH activity in the SME of cycling (diestrous) rats was not altered after either central (65 h) or peripheral (12 days) administration of cells. TH mRNA levels in the arcuate nuclei were unaltered by Rcho cells in immature female and adult cycling rats. TH mRNA levels in ovariectomized rats were markedly reduced 75% by 50 h of bromocriptine treatment and modestly reduced 33% 65 h after injection of Rcho cells. However, Rcho cells partially reversed the bromocriptine-induced decline in TH mRNA to levels seen for Rcho cells alone. On day 7 of pregnancy, secretions from Rcho cells abolished the nocturnal and diurnal PRL surges characteristic of early pregnancy and suppressed circulating PRL levels throughout the day to less than 20% of intersurge PRL levels. Rcho cells eliminated the semicircadian rhythm in TH activity in the SME, which was out of phase with the twice daily PRL surges of early pregnancy. TH activity was increased by Rcho factor(s) at 0330 h (nocturnal surge) and 1800 h (diurnal surge), but not at 1000 h (intersurge). MMQ cells, pituitary-derived clonal PRL-secreting cells, similarly terminated the biphasic rhythm of PRL release and tuberoinfundibular dopaminergic neuronal activity during early pregnancy.(ABSTRACT TRUNCATED AT 400 WORDS)

Identification of a large pre-lysosomal compartment in the pathogenic protozoon Trypanosoma cruzi

Epimastigote forms of the pathogenic parasite Trypanosoma cruzi were used to study the endocytic process in a protozoon. These elongated unicellular organisms are highly polarized cells: endocytosis occurs only at the anterior region through the cytostome and the flagellar pocket membrane, areas of the plasma membrane where the cell cytoskeleton, formed by sub-pellicular microtubules, is absent. When the cells were incubated at 4 degrees C or 28 degrees C with gold-labeled transferrin, fixed and processed for routine transmission electron microscopy our observations show that this ligand initially binds to the cytosome and the membrane lining the flagellar pocket and is subsequently ingested through a clathrin-independent receptor-mediated endocytotic process, with formation of uncoated pits and vesicles. Ingested complexes are carried in uncoated vesicles to the reservosomes, large membrane-bound organelles found mostly at the posterior end of the cell. Immunocytochemical data from Lowicryl-embedded cells demonstrated that the reservosomes are acidic compartments (pH 6.0, as shown using DAMP as a pH probe) with no acid phosphatase or typical lysosome-associated membrane proteins (LAMP 1, LAMP 2 and lgp 120), but rich in cysteine proteinase. These data suggest that the reservosome is a pre-lysosomal compartment. Since cysteine proteinase of T. cruzi contains no phosphorylated mannose residues and the cation-independent mannose 6-phosphate receptor could not be immunocytochemically detected in the reservosomes, it is possible that lysosomal enzymes in the epimastigote forms of T. cruzi are targeted to compartments related to the endocytic pathway through a mechanism different from that which occurs in other eukaryotic cells.

Thermic effect of a meal. 2. Role in chronic undernutrition

The thermic effect of a standard liquid meal (TEM; energy 2.5 MJ; containing (g/kg) protein 100, fat 150, carbohydrate 750; volume 350 ml) was measured in a chronically undernourished (UN; n 9) group of human subjects and was compared with results from two control groups, one normal weight (NW)-for-height (BMI greater than 20; n 10) and the other underweight (UW)-for-height (BMI less than 18, n 10), using a ventilated-hood system over a period of 6 h after ingestion of the meal. Results indicated that the UN subjects had lower values for body-weight, height, percentage fat and fat-free mass (FFM) compared with those of either control group. Basal metabolic rates were lowest in the UN group in absolute terms; however, there were no significant differences among groups on an analysis of covariance (ANACOVA) with FFM as the covariate. TEM responses in the UN group were significantly higher when expressed either in absolute terms or as a percentage of the energy density of the meal. The post-meal total energy output was significantly lower (P less than 0.05) in the UW and UN groups as compared with the NW group in absolute terms; however, on adjusting for differences in FFM (by ANACOVA) there were no significant differences among groups. This would suggest that in the chronically undernourished thermogenic responses to a meal are unlikely to contribute towards any energy saving and may not constitute a part of any adaptive response to the undernourished state.

Ultrastructural aspects of Trypanosoma (Megatrypanum) freitasi in co-cultivation with mammalian cells

Cultures of Trypanosoma (Megatrypanum) freitasi with L929 mouse fibroblasts at 27.5 degrees C were examined by scanning and transmission electron microscopy in an attempt to clarify the processes of colony formation by the epimastigotes and of their attachment to substrata. It was seen that the flagellates occupy intercellular spaces and do not associate with intact fibroblasts. As the trypanosome population increases, ever larger portions of the substratum are cleared of fibroblasts and occupied by conglomerates of epimastigote colonies consisting of about a dozen organisms that attach to the substratum by their anterior extremities and form pyramidal clusters. Attachment of the epimastigotes involves the flagellar membrane, which becomes extraordinarily enlarged and assumes various aspects of broad sheets, filaments and loops over the substratum or along the flagellum, which exhibits a shortened axoneme. Desmosome or hemidesmosome plaques are present when the attachment takes place between membranes or between the membrane and the substratum.

Thermic effect of a meal. 3. Effect of dietary supplementation in chronically undernourished human subjects

Five apparently healthy, chronically undernourished (UN) male volunteers aged between 18 and 30 years were studied before and after 12 weeks of dietary supplementation. The thermic effect of a meal (TEM) was measured over a period of 6 h using a ventilated-hood system. Results indicated a significant increase in body-weight after supplementation due to increases in body fat and fat-free mass (FFM) in the proportion of 69% and 31% respectively. The basal metabolic rates (BMR) measured post supplementation were significantly higher in absolute terms, with a trend towards higher values when adjusted for the changes in FFM. TEM responses measured after 12 weeks of supplementation were significantly lower when expressed either in absolute terms (presupplementation 227.0 kJ v. post supplementation 193.5 kJ), or as a percentage of the energy density of the meal (9.1% v. 7.7%). This lower TEM was reciprocal to the changes in the BMR (r -0.86). The post-meal total energy output (PMTEO) was, however, not significantly different after 12 weeks of dietary supplementation. The unchanged PMTEO would indicate an unaltered 'thermogenic capacity', following supplementation, in these chronically undernourished subjects. These results confirm our earlier conclusion that, in chronic undernutrition, the thermic response to a meal may not contribute to any energy saving.

Thermic effect of a meal. 1. Methodology and variation in normal young adults

The variation in the thermic effect of a meal (TEM) was investigated in two groups of five subjects following a standard test meal. Results demonstrated a 50% lower response over 6 h, in the same subjects, when measured intermittently (protocol 2) as compared with a continuous measurement (protocol 1). The variation in TEM among occasions (measured on three occasions in each subject) was large (coefficient of variation (CV) 18.7%, P less than 0.02). However, the post-meal total energy output (CV 1.4%, P greater than 0.05), non-protein respiratory quotient (CV 1.9%, P greater than 0.05) and substrate oxidation rate were not different (P greater than 0.05) in the same individual on separate occasions. Small variations in the basal metabolic rate (BMR) from occasion to occasion (CV 2.6%) contributed to the variation in TEM. However, after allowing for the changes in BMR, variation in TEM (CV 8.6%, P greater than 0.05) was still sizeable though not statistically significant.

Molecular cloning and characterization of prolactin-like protein C complementary deoxyribonucleic acid

In this report, we describe the isolation and characterization of a full length cDNA clone for rat prolactin-like protein C (PLP-C) and describe the expression of PLP-C mRNA in the developing rat placenta. Nucleotide sequence analysis of the PLP-C cDNA clone predicted a mature protein of 238 amino acids, including a 30-amino acid signal sequence. The predicted PLP-C amino acid sequence contains seven cysteine residues, three tryptophan residues, and two putative N-linked glycosylation sites. Six of the cysteine residues in PLP-C are located in positions homologous to the cysteines of pituitary prolactin (PRL). Additional sequence similarities with pituitary PRL and other members of the rat placental PRL family are evident. The PLP-C gene was localized to rat chromosome 17. Northern blot analysis showed that the PLP-C cDNA clone specifically hybridized to a 1.0-kilobase mRNA. PLP-C mRNA was first detectable between days 13 and 14 of gestation, peaked by day 18 of gestation, and remained elevated until term. In situ hybridization analysis indicated that PLP-C mRNA was specifically expressed by spongiotrophoblast cells and some trophoblast giant cells in the junctional zone region of rat chorioallantoic placenta.

Trophoblast cell differentiation: establishment, characterization, and modulation of a rat trophoblast cell line expressing members of the placental prolactin family

The purpose of this investigation was to establish and characterize a cell line derived from a rat choriocarcinoma and to evaluate the usefulness of the cell line as an in vitro model for studying trophoblast cell differentiation. A cell line was generated from choriocarcinoma explants and named Rcho-1. The cell line consisted of a mixture of cell types, including small cells growing in clusters and giant cells possessing very large nuclei. This characteristic morphology was maintained through at least 23 passages and in a series of clonal cell lines isolated from the parent Rcho-1 cell line. The Rcho-1 cell line was capable of expressing placental lactogen-I (PL-I), PL-II, PRL-like protein-A (PLP-A), and PLP-C mRNAs when cultivated in vitro; however, the Rcho-1 cells expressed only PL-I when grown beneath the kidney capsule of host rats. The Rcho-1 cell line did not express PLP-B under any experimental condition. This pattern of placental PRL expression was maintained for 23 passages. Rcho-1 cells synthesized and secreted PL-I, PL-II, and PLP-A proteins with biochemical characteristics similar to those of their placental counterparts. PL-I and PL-II mRNAs were specifically localized to giant cells. Morphological appearance and placental PRL expression were used as indices for monitoring the differentiation state of Rcho-1 cells grown under various conditions. Both morphological and functional trophoblast cell differentiation were induced by maintaining the Rcho-1 cells in postconfluent culture conditions. Postconfluent Rcho-1 cultures were characterized by an increased percentage of giant cells and an induction of placental PRL expression. Some clonal cell lines derived from the parent Rcho-1 cell line exhibited distinct patterns of differentiation and placental PRL expression. In summary, we have established a rat trophoblast cell line capable of expressing a differentiated phenotype. The differentiated phenotype includes both morphological and functional parameters and can be modulated in vitro. This cell line is a unique model for studying the control of placental PRL gene expression and the regulation of trophoblast cell differentiation.

Basal metabolic rate, body composition and whole-body protein turnover in Indian men with differing nutritional status

1. Three groups of adult men were studied in Bangalore, India: two groups were controls who had been receiving an adequate diet. Of these, one group, designated 'normal weight controls', had a mean body mass index of 22; the other group, 'underweight controls', had a mean body mass index of 16.7. The third group consisted of poor labourers, whose daily food intake had been less than 10 MJ and whose mean body mass index was 16.6. Previous studies had shown that such men had a lower basal metabolic rate than well-nourished Indian control subjects. 2. The object of the present study was to find out whether a reduced rate of protein turnover, measured after a single dose of [15N]glycine, contributed to a lower basal metabolic rate. It was found, however, that after adjusting for body weight and fat-free mass by analysis of co-variance there was no significant difference in basal metabolic rate between the three groups. Adjusted rates of protein synthesis were higher in the underweight controls and the undernourished labourers than in the normal weight controls, but not significantly so. 3. Estimates based on creatinine excretion showed that within the fat-free mass the underweight groups had a higher proportion of non-muscle to muscle mass. This may explain the somewhat higher rates of protein turnover in these groups. 4. Nitrogen flux (Q) was determined from 15N abundance in two end products, urea (QU) and ammonia (QA). In the underweight and undernourished groups the ratio QU/QA was increased compared with the normal weight group.(ABSTRACT TRUNCATED AT 250 WORDS)

Herpetomonas roitmani (Fiorini et al., 1989) n. comb.: a trypanosomatid with a bacterium-like endosymbiont in the cytoplasm

The trypanosomatid previously described as Crithidia roitmani is characterized here at the ultrastructural and biochemical levels. The data indicates that the parasite belongs to the Herpetomonas genus, and we therefore suggest the flagellate to be denominated as Herpetomonas roitmani n. comb. Cladistic analysis of isoenzyme data generated by eight different enzymes showed that the parasite presented a distinct banding pattern and could be grouped with some Herpetomonas spp., but not with Crithidia spp., used as reference strains. Accordingly, when the parasites were grown for longer periods in Roitman's defined medium, expontaneous differentiation from promastigotes to opisthomastigotes (typical of the Herpetomonas genus) occurred. Transmission electron microscopy revealed the presence of bacterium-like endosymbionts in the cytoplasm of all evolutive forms of the parasite. All morphological alterations characteristic of endosymbiont-bearing trypanosomatids could be observed.

Turkey and chicken prolactins stimulate the proliferation of rat Nb2 lymphoma cells

The purpose of this investigation was to assess the actions of two avian prolactins (PRL) on rat Nb2 lymphoma cell proliferation. Various turkey and chicken PRL preparations stimulated the proliferation of rat Nb2 cells. The ability of avian PRL preparations to influence the behavior of rat Nb2 lymphoma cells provides a useful method for monitoring the PRL-like actions of native and recombinant avian PRL and suggests a potential role of PRL in modulating the avian immune system.

Generation and characterization of antipeptide antibodies to rat cytochrome P-450 side-chain cleavage enzyme

In this report, we describe the generation of immunologic probes to rat P-450scc. Two regions of the P-450scc amino acid sequence were identified (internal domain: amino acids 421-441; carboxy terminal domain: amino acids 509-526), chemically synthesized and used as immunogens in rabbits. Antibody production was monitored by enzyme-linked immunoassay (EIA) and Western blot analyses. Antisera were successfully generated to each of the P-450scc regions that recognized the entire 49 kDa rat P-450scc protein. Antiserum directed to the internal domain of P-450scc showed broad species crossreactivity, whereas antiserum directed to the carboxy terminal domain of P-450scc crossreacted with only rat and mouse. Both antisera were useful for Western blot and immunocytochemical analyses of rat P-450scc expression. In addition to recognizing the major 49 kDa P-450scc protein, each antiserum also recognized lower molecular weight species. Antiserum directed to the internal domain of P-450scc specifically recognized a 42 kDa species, whereas antiserum directed to the carboxy terminal domain specifically recognized an 8 kDa species. We hypothesize that the two lower molecular weight immunoreactive species are generated by proteolytic cleavage of rat P-450scc between the internal and carboxy terminal epitopes.

Basal metabolic rates and metabolic economy in chronic undernutrition

Basal metabolic rates (BMR) and body composition were measured in 130 adult Indian males, selected from three socio-economic groups. Results show a significantly lower BMR in the chronically undernourished, with a greater dependence on carbohydrate as fuel in the fasted state. When expressed as per kg body weight or kg fat-free mass (FFM), the BMRs are significantly higher in these individuals. The latter observations suggest variations in the contribution of viscera and skeletal muscle to the FFM, with a relatively greater visceral to muscle mass ratio. However, on adjustment for differences in weight and FFM by means of an analysis of covariance, the chronically undernourished (both urban and rural) have significantly lower BMRs. This indicates a 'metabolic economy' in these individuals, which could be attributable in part to their significantly lower serum T3 levels. When the subjects are classified on the basis of grades of chronic energy deficiency (CED), individuals with low body mass index (BMI) (less than 17 and below) are not similar in their basal metabolism. Those individuals from good socio-economic backgrounds with access to ad libitum energy and protein intake but with low BMI have comparable BMRs to the well nourished. It may therefore be unwise to classify all individuals with low BMI 'across the board' as suffering from CED. Socio-economic scaling may be a useful addition to the present classification of CED.

Identification and immunochemical characterization of a major placental secretory protein related to the prolactin-growth hormone family, prolactin-like protein-C

Trophoblast cells of the rat chorioallantoic placenta synthesize and secrete a number of proteins structurally related to pituitary PRL. During the purification of one member of the placental PRL family, PRL-like protein-A (PLP-A), we identified a major contaminating protein with a similar mol wt but possessing a more acidic pI (5.9-6.1) and different immunoreactivities. After isolation by two-dimensional gel electrophoresis, the more acidic contaminating protein was electroeluted, and its N-terminal amino acid sequence was determined by gas phase sequencing. The N-terminal sequence showed considerable homology with members of the PRL family, including characteristic positioning of cysteine residues at amino acids 4 and 11. The newly identified protein species have been termed PLP-C based on their structural similarity with pituitary PRL. The protein was further characterized by the generation of specific immunological probes. Antibodies were generated to electrophoretically purified protein and to a chemically synthesized peptide representing amino acids 11-32 of its N-terminal sequence. Each antiserum specifically recognized two major species migrating at approximately 25 and 29 kDa, respectively. The 29-kDa species specifically bound to Concanavalin-A, while the 25-kDa species failed to bind to the lectin. Furthermore, the 29-kDa species could be converted to the 25-kDa species by enzymatic deglycosylation. The antisera have also been used to examine the cell- and temporal-specific patterns of expression. The immunoreactive protein species (25 and 29 kDa) were localized primarily to spongiotrophoblast cells present in the junctional zone of the chorioallantoic placenta. Expression was initiated after midgestation and increased during the remaining part of gestation. In summary, PLP-C is a major secretory protein produced by spongiotrophoblast cells during the second half of gestation.

Endocytosis of gold-labeled proteins and LDL by Trypanosoma cruzi

Endocytosis was studied at the ultrastructural level in different developmental forms of Trypanosoma cruzi after incubation of the parasites in the presence of gold-labeled proteins (albumin-Au, peroxidase-Au and transferrin-Au) and low-density lipoprotein (LDL-Au). Epimastigote (culture) forms actively ingested LDL and proteins. Initially, gold particles were seen adhering only to the cytostome and inside the flagellar pocket. In parasites incubated at 4 degrees C with transferrin-Au or peroxidase-Au, labeling was found only at these two sites, showing that receptor-mediated endocytosis occurs in both regions. In the cytoplasm, gold particles were seen only inside two different compartments: membrane-bound vesicles and reservosomes. Incubation of epimastigotes with acridine orange followed by fluorescence microscopy revealed intense orange staining, indicating that the reservosomes have an acidic pH. This staining was abolished after incubation of the parasites in the presence of ammonium chloride. These data confirm that this compartment is the site of accumulation of ingested lipids and proteins. Little intracellular labeling with transferrin-Au was found in in vitro-derived amastigotes and trypomastigotes (both lack reservosomes). However, although in amastigotes very few gold particles were seen bound to the cells, in trypomastigotes they were observed bound to the membrane that encloses the cell body, the flagellar pocket, and the flagellum, suggesting that the receptors are more abundant in this form.