Understanding new molecular and cell biology findings based on progressive scientific practices and interconnected activities in undergraduate students.

Nowadays Molecular Cell Biology (MCB) must be taught as science is practiced. Even though there are several approaches based on scientific practices, a key aspect is to define the purpose of each of these teaching strategies and, most importantly, their implementation. Our goal was to train students to acquire, understand, and communicate new scientific knowledge in the field. The main feature of our new teaching methodology was progressive training in scientific practices associated with a back-and-forward interplay between activities and assessments. The methodology was implemented over 4 years, in students attending the MCB course of the undergraduate degree in Biological Sciences. In the first two modules, the students were prepared to comprehend MCB concepts and techniques and to experience activities based on scientific practices. In the third module, the students analyzed a primary paper in-depth. They were assessed by midterm exams based on a primary paper, written laboratory reports, and the oral presentation of a scientific paper. Our teaching proposal was evaluated through the students' academic performance and by their opinion on the teaching methodology. Most students were satisfied since they improved their acquisition of concepts, their interpretation and integration of scientific knowledge, and developed skills to communicate scientific knowledge in writing and orally. The novelty of transversal interconnections and progressive training in scientific practices provides students with skills in acquiring and understanding new scientific information, even beyond the MCB course.

Epithelial cell protein milk fat globule-epidermal growth factor 8 and human chorionic gonadotropin regulate stromal cell apoptosis in the human endometrium.

OBJECTIVE: To study the regulation of apoptosis in human endometrial cells. The specific aims were to determine whether milk fat globule-epidermal growth factor 8 (MFG-E8), a novel endometrial epithelial protein, modulates caspase activation and DNA fragmentation; and to examine whether hCG, an early embryonic product, regulates Bax and Bcl-2 equilibrium, as well as MFG-E8 expression. DESIGN: Primary cultures of human endometrial epithelial cells (EECs) and endometrial stromal cells (ESCs). SETTING: Academic center. PATIENT(S): Ovulatory women aged 21-30 years. INTERVENTION(S): Treatment with MFG-E8 and hCG. MAIN OUTCOME MEASURE(S): Apoptotic activity was quantified using a luciferase assay. Deoxyribonucleic acid fragmentation was detected by TUNEL assay. Bax, Bcl-2, and MFG-E8 messenger RNA expression levels were determined by quantitative reverse transcription-polymerase chain reaction. Immunocytochemistry was used to establish cell purity and presence of MFG-E8 and hCG-R (receptor) proteins. RESULT(S): Endometrial epithelial cells were cytokeratin(+), vimentin(-), MFG-E8(+), and hCG-R(+), whereas ESC were vimentin(+), cytokeratin(-), MFG-E8(-), and hCG-R(+). Treatment of ESC with MFG-E8 resulted in a 13-fold increase in caspase activity and a 30-fold increase in TUNEL. On the other hand, hCG decreased messenger RNA expression of Bax in ESC. CONCLUSION(S): Milk fat globule-epidermal growth factor 8 has proapoptotic activity, suggesting participation in endometrial remodeling via an epithelial-stromal cell paracrine effect. Conversely, pregnancy levels of hCG has opposite effects on stromal cells.

Expression of milk fat globule EGF-factor 8 (MFG-E8) mRNA and protein in the human endometrium and its regulation by prolactin.

Milk fat globule epidermal growth-factor 8 (MFG-E8) has not been previously linked to endometrial physiology. We reported on MFG-E8 mRNA up-regulation in the human endometrium during the window of implantation (WOI) using microarrays. Prolactin (PRL) secreted by stromal cells has been suggested to modulate protein expression. The objective of this study was to characterize the endometrial expression of MFG-E8 and its ligand αvß3 integrin during the menstrual cycle and its possible regulation by PRL. MFG-E8 mRNA (real-time RT-PCR) and protein expression (immunohistochemistry and immunoblotting) were analyzed in human endometrial biopsies at different times of the menstrual cycle, as well as in primary endometrial cell cultures. In primary cultures of epithelial cells, MFG-E8 intracellular protein expression was evaluated in absence or presence of PRL (0.2 and 1 µg/ml). The results show that MFG-E8 protein is almost exclusively localized to the epithelium in whole endometrial biopsies. Both MFG-E8 mRNA and protein expression increased in the luteal phase and were highest during the WOI; epithelial protein location of αvß3 integrin also peaked on cycle Day 24. Cultured epithelial cells showed a diffuse staining of MFG-E8 over the cytoplasmic area; however, some cells presented a punctuated staining pattern. PRL treatment of epithelial cells for 72 h in vitro significantly increased MFG-E8 protein intracellular expression. This is the first report on MFG-E8 protein localization to the human endometrial epithelium and its up-regulation during the WOI. The pattern of glandular expression of its ligand αvß3 integrin was remarkably similar. In vitro data support a modulatory role for PRL as a stromal/epithelial paracrine factor controlling MFG-E8.

Do GnRH analogues directly affect human endometrial epithelial cell gene expression?

We examined whether Gonadotrophin-releasing hormone (GnRH) analogues [leuprolide acetate (LA) and ganirelix acetate (GA)] modulate gene expression in Ishikawa cells used as surrogate for human endometrial epithelial cells in vitro. The specific aims were: (i) to study the modulatory effect of GnRH analogues by RT-PCR [in the absence and presence of E(2) and P4, and cyclic adenosine monophosphate (cAMP)] on mRNA expression of genes modulated during the window of implantation in GnRH analogues/rFSH-treated assisted reproductive technology cycles including OPTINEURIN (OPTN), CHROMATIN MODIFYING PROTEIN (CHMP1A), PROSAPOSIN (PSAP), IGFBP-5 and SORTING NEXIN 7 (SNX7), and (ii) to analyze the 5'-flanking regions of such genes for the presence of putative steroid-response elements [estrogen-response elements (EREs) and P4-response element (PREs)]. Ishikawa cells were cytokeratin+/vimentin- and expressed ERalpha, ERbeta, PR and GnRH-R proteins. At 6 and 24 h, neither LA nor GA alone had an effect on gene expression. GnRH analogues alone or following E(2) and/or P4 co-incubation for 24 h also had no effect on gene expression, but P4 significantly increased expression of CHMP1A. E(2) + P4 treatment for 4 days, alone or followed by GA, had no effect, but E(2) + P4 treatment followed by LA significantly decreased IGFBP-5 expression. The addition of 8-Br cAMP did not modify gene expression, with the exception of IGFBP-5 that was significantly increased. The GnRH analogues did not modify intracellular cAMP levels. We identified conserved EREs for OPN, CHMP1A, SNX7 and PSAP and PREs for SNX7. We conclude that GnRH analogues appear not to have major direct effects on gene expression of human endometrial epithelial cells in vitro.

DNA fragmentation of normal spermatozoa negatively impacts embryo quality and intracytoplasmic sperm injection outcome.

OBJECTIVE: To evaluate DNA fragmentation in morphologically normal sperm recovered from the same sample used for intracytoplasmic sperm injection (ICSI) and to correlate DNA damage with embryo quality and pregnancy outcome. DESIGN: Prospective study. SETTING: Academic center. PATIENT(S): 36 infertile men participating in the ICSI program. INTERVENTION(S): Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-fluorescein nick end labeling (TUNEL) assay and morphologic assessment by phase contrast. MAIN OUTCOME MEASURE(S): Simultaneous assessment of sperm morphology and DNA fragmentation by TUNEL assay was performed in the same cell, then the percentage of normal sperm with fragmented DNA (normal SFD) was correlated with embryo quality and pregnancy outcomes. RESULT(S): A highly statistically significant negative correlation was found between the percentage of normal SFD and embryo quality. This association was confirmed for the transferred embryos and for the total embryo cohort. The receiver operating characteristics curve analysis demonstrated that the percentage of normal SFD and embryo quality were statistically significant predictors of pregnancy. When the percentage of normal SFD was

Pregnancy-specific {beta}-1-glycoprotein 1 and human leukocyte antigen-E mRNA in human sperm: differential expression in fertile and infertile men and evidence of a possible functional role during early development.

BACKGROUND: Mature spermatozoa contain thousands of mRNA transcripts. It has been recently shown that human sperm can deliver RNA into the oocyte, suggesting that mRNAs might have a role before or after fertilization. Human embryos express PSG1 (pregnancy-specific beta-1-glycoprotein 1) and HLA-E (human leukocyte antigen-E), molecules playing a role in implantation and early development. We compared PSG1 and HLA-E sperm mRNA levels in fertile and infertile men and we tested the hypothesis that these transcripts are selectively retained in the newly formed zygote. METHODS: Real-time RT-PCR was used to analyze sperm mRNA levels (n = 11 fertile, n = 31 infertile patients) of PSG1, HLA-E and PRM2 (protamine 2). The presence of PSG1 and HLA-E proteins was evaluated by western blot in sperm protein extracts (n = 3). Using ICSI of human sperm into hamster oocytes we evaluated the permanence of these mRNAs at different time points (n = 10 for each time) after fertilization. RESULTS: PSG1, HLA-E and PRM2 transcripts were demonstrated in ejaculated sperm. The fertile group showed significantly higher levels of PSG1 and HLA-E mRNA (both P < 0.05) than the infertile group, whereas PRM2 levels were not significantly different. However, PSG1 and HLA-E proteins were not found in ejaculated sperm. Following ICSI, PRM2 was undetectable after fertilization; conversely, PSG1 and HLA-E transcripts remained detectable for at least 24 h of zygotic development. CONCLUSIONS: We provide new evidence that indicates that human sperm deliver transcripts that may have a role in early embryo development and decreased levels of these transcripts may be associated with infertility.

Fragmentation of DNA in morphologically normal human spermatozoa.

OBJECTIVE: To evaluate DNA fragmentation in spermatozoa with normal morphological appearance. DESIGN: Prospective study. SETTING: Academic tertiary center. PATIENT(S): Fertile, subfertile, and infertile men were studied. INTERVENTION(S): Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-fluorescein nick-end labeling assay and morphology assessment by phase contrast in the swim-up fractions. MAIN OUTCOME MEASURE(S): Simultaneous assessment of the percentage of normally shaped sperm and DNA fragmentation. RESULT(S): No DNA fragmentation was found in spermatozoa with normal morphology in any of the samples from the fertile group. In only one sample from the subfertile group did we observed normally shaped sperm cells exhibiting DNA fragmentation. However, in all the samples from the infertile group, we observed normal spermatozoa with DNA fragmentation. Spermatozoa from this late group exhibited a high proportion of DNA damage. CONCLUSION(S): In infertile men with moderate and severe teratozoospermia, the spermatozoa with apparently normal morphology present in the motile fractions after swim-up may have DNA fragmentation.

Expression of immunomodulatory genes, their protein products and specific ligands/receptors during the window of implantation in the human endometrium.

We have demonstrated up-regulation of the immunomodulatory genes decay accelerating factor (DAF), interleukin 15 (IL-15) and osteopontin (OPN) during the window of implantation (WOI). Here, we characterized gene expression and determined the localization of their protein products and respective ligands at the opening and closure of the WOI. In addition, we used laser capture microdissection (LCM) to analyze the cell type-specific gene expression. Human endometrial biopsies from cycle Days 16, 21 and 24 were evaluated by real-time RT-PCR. Purified epithelial and stromal cells were obtained by LCM. Localization of the proteins and their ligands was assessed by immunohistochemistry. mRNA expression of DAF, IL-15 and OPN was significantly increased throughout the WOI. DAF, OPN and alpha(v)beta(3) integrin were strongly immunolocalized to the glandular compartment by Days 21 and 24, whereas C3, IL-15 and IL-15Ralpha were highly stained in both glandular and stromal compartments. After LCM, gene expression of DAF was 4.8-fold increased in epithelium versus stroma, whereas for OPN there was a 2-fold increase. For IL-15, the expression in stroma was 8.7-fold higher than in epithelial cells. The progressive increase of the expression of these immunomodulatory genes, proteins and ligands during the WOI, support a critical role at the time of endometrial receptiveness.