Signatures of Divergence, Invasiveness, and Terrestrialization Revealed by Four Apple Snail Genomes.

The family Ampullariidae includes both aquatic and amphibious apple snails. They are an emerging model for evolutionary studies due to the high diversity, ancient history, and wide geographical distribution. Insight into drivers of ampullariid evolution is hampered, however, by the lack of genomic resources. Here, we report the genomes of four ampullariids spanning the Old World (Lanistes nyassanus) and New World (Pomacea canaliculata, P. maculata, and Marisa cornuarietis) clades. The ampullariid genomes have conserved ancient bilaterial karyotype features and a novel Hox gene cluster rearrangement, making them valuable in comparative genomic studies. They have expanded gene families related to environmental sensing and cellulose digestion, which may have facilitated some ampullarids to become notorious invasive pests. In the amphibious Pomacea, novel acquisition of an egg neurotoxin and a protein for making the calcareous eggshell may have been key adaptations enabling their transition from underwater to terrestrial egg deposition.

Twenty years of the 'Preparation for Oxidative Stress' (POS) theory: Ecophysiological advantages and molecular strategies.

Freezing, dehydration, salinity variations, hypoxia or anoxia are some of the environmental constraints that many organisms must frequently endure. Organisms adapted to these stressors often reduce their metabolic rates to maximize their chances of survival. However, upon recovery of environmental conditions and basal metabolic rates, cells are affected by an oxidative burst that, if uncontrolled, leads to (oxidative) cell damage and eventually death. Thus, a number of adapted organisms are able to increase their antioxidant defenses during an environmental/functional hypoxic transgression; a strategy that was interpreted in the 1990s as a "preparation for oxidative stress" (POS). Since that time, POS mechanisms have been identified in at least 83 animal species representing different phyla including Cnidaria, Nematoda, Annelida, Tardigrada, Echinodermata, Arthropoda, Mollusca and Chordata. Coinciding with the 20th anniversary of the postulation of the POS hypothesis, we compiled this review where we analyze a selection of examples of species showing POS-mechanisms and review the most recent advances in understanding the underlying molecular mechanisms behind those strategies that allow animals to survive in harsh environments.

Aging and retinoid X receptor agonists on masculinization of female Pomacea canaliculata, with a critical appraisal of imposex evaluation in the Ampullariidae.

Ampullariidae are unique among gastropods in that females normally show a primordium of the copulatory apparatus (CApp). The aims of this study were (a) to quantitatively evaluate the development and growth of the female CApp with age; (b) to compare the effects of RXR and PPARγ agonists in adult females of known age and (c) to explore the effect of masculinizing RXR agonists on the expression of RXR in the CApp. It was found that the CApp grows and develops with age. A significant increase in penile sheath length (PsL) and also in a developmental index (DI) was observed in 7-8 months old females, as compared with 4-5 months old ones. A reported endogenous agonist of RXR, 9-cis retinoic acid (9cis-RA), as well as two organotin compounds, tributyltin (TBT) and triphenyltin (TPT) which have been also reported to bind to RXR, were injected and its masculinizing effects were measured. Also, the effect of a PPARγ agonist, rosiglitazone, was studied. All studied RXR agonists, but not the PPARγ agonist, were effective in increasing PsL, penile length (PL) and DI. Finally, the expression of the RXR in the CApp was studied (Western blot) in control, TBT, TPT, and 9cis-RA treated females. A significantly increased expression of RXR was only observed after 9cis-RA treatment. It is concluded that (a) development and growth of the CApp is significantly affected by female age; (b) reported RXR agonists, but not a PPARγ agonist, cause female masculinization of young females. An appraisal of previous studies of female masculinization in the Ampullariidae has also been made and it is emphasized that the masculinizing effect of aging should be considered, particularly when interpreting field data.

An efficient microwave-assisted synthesis of cotinine and iso-cotinine analogs from an Ugi-4CR approach.

A convenient base-mediated two-step synthesis of cotinine analogs and a one-pot base-free synthesis of iso-cotinine derivatives featuring an Ugi-4CR/cyclization protocol are reported. These approaches exploit the reactivity of the peptidyl position present in the Ugi adducts, allowing the facile construction of the γ-lactam core, as well as the introduction of a N-substituted methyl group into the analogs in a straightforward manner. A plausible mechanism for the cyclization step is discussed.

Laparoscopic Approach for Fibroid Removal at 18 Weeks of Pregnancy.

Leiomyomas are the most frequently solid tumors found in pregnancy. This kind of tumor has a wide incidence depending on the age, race, and type of population studied. Most of the cases have an asymptomatic course; however, they could develop different kinds of complications during the pregnancy such as severe abdominal pain, often due to degeneration or torsion with ischemia. In these cases, a surgical approach is required because these tumors do not respond to the conventional treatment. Very few of these cases are reported in the literature. We report the case of a 36-year-old woman pregnant 18 weeks, who experienced acute abdominal pain without initial reponse to regular analgesics. She was taken to the operating room, and under laparoscopic exploration, torsion of a subserosal myoma was observed. The fibroid was resected laparoscopically, and she was released from the hospital without complications. Unfortunately, she was readmitted 45 days later with signs of preterm labor because of a motorcycle accident. An emergency cerclage was performed, but the pregnancy was compromised with amnionitis and early fetal demise. We concluded that the laparoscopic approach could be a successful alternative treatment in selected cases.

Combinatorial synthesis of nicotine analogs using an Ugi 4-CR/cyclization-reduction strategy.

A practical one-pot synthesis of nicotine analogs from Ugi 4-CR/propargyl adducts is reported. This methodology allows the rapid construction of the pyrrolidine moiety present in nicotine through an intramolecular base-promoted 5-endo cycloisomerization process, followed by a reduction of the resulting mixture of 2- and 3-pyrrolines to afford nicotine analogs in good overall yields.

In vitro determination of the short-chain synthetic peptide RP13 antimicrobial activity.

BACKGROUND: The proliferation of antibiotic-resistant microorganisms, along with the lack of new drugs against them, has elicited the interest of the scientific community on the study and development of endogenous synthetic compounds with bacteriostatic or bactericidal activity. In recent years, several short-chain, low molecular weight peptides isolated from natural sources such as plants and animals have demonstrated an array of antimicrobial activities. Despite having structural characteristics similar to microbicidal peptides isolated from human platelets, peptide RP11 does not exhibit antimicrobial activity. OBJECTIVE: In vitro determination of the antimicrobial activity of the synthetic peptide RP13. MATERIAL AND METHODS: Peptide RP13 was prepared modifying the original amino acids sequence of peptide RP11, reversing the position of the amino acids lysine and tyrosine in order to modify the conformation of the original peptide. These amino acids are localized close to the N-terminus of the peptidic chain. Peptide RP13 was prepared in solution using conventional methods for peptide synthesis. The antimicrobial activity of RP13 was assessed against the microorganisms S. aureus, E. faecalis and E. coli in a test solution and later evaluated by cultivation of plates during the first 2 h after inoculation of bacteria. RP13 activity antimicrobial was compared against tetracycline, a broad-spectrum antibiotic. RESULTS: The new peptide RP13, resulting form the structural modification of the amino acid sequence of peptide RP11, displayed antimicrobial activity. RP13 demonstrated to be more efficient inhibiting the growth of gram-positive than gramnegative bacteria. CONCLUSIONS: The structural modification of peptide RP11, obtained from human platelets, resulted in a new peptide with improved antimicrobial activity. These results clearly demonstrate that peptides of natural origin, as well as their synthetic analogs, represent an attractive alternative against pathogenic agents.

Progesterone levels on hCG day and oocyte maturation in a Mexican IVF program.

OBJECTIVE: Does progesterone levels on hCG day influence maturation rates and number of mature oocytes during ovarian stimulation for IVF/ICSI cycles?. METHODS: A retrospective, observational, analytic, cross-sectional and cohort study was performed at the Reproductive Endocrinology Department of the Centro Médico Nacional 20 de Noviembre in Mexico City between 2015 to 2020. All female patients underwent an ovarian stimulation cycle for IVF/ICSI, either with a mild or conventional stimulation protocol. Patients were classified according to their progesterone levels, Group 1 <1.5ng/ml and Group 2 >1.5mg/ml. A Spearman Rho test, a simple linear regression model, a Principal Component Analysis and a Student's T-test, were performed. RESULTS: A total of 600 patients were included. The overall results showed that there is a positive correlation between the number of retrieved, mature oocytes and progesterone levels on HCG day. After the Principal Component Analysis we observed that poor ovarian responders had the lowest maturation rate and number of mature oocytes. While the Student's t test showed that progesterone levels beyond 1.5ng/ml are associated to a higher number of mature oocytes but not a better maturation rate. CONCLUSIONS: Higher serum progesterone levels are associated with increased retrieved and mature oocytes in high responders. At the same time, higher progesterone levels in lower responders are not associated with optimal ovarian response.

High ovarian responders have the highest risk of premature progesterone rise.

OBJECTIVE: Late follicular phase progesterone elevation is a complication that affects approximately 38% of IVF cycles. There is a lack of consensus on the appropriate cut-off levels for progesterone on hCG day. Although premature progesterone rise occurs in all kinds of ovarian responses, there is a knowledge gap regarding the ovarian response with the highest risk of this phenomenon. Our study aims to assess the relative risk of each kind of ovarian response for premature progesterone rise and evaluate the prevalence of premature progesterone rise in each ovarian response. METHODS: A retrospective, cross-sectional, comparative and analytic study was performed at the Reproductive Endocrinology Department in Centro Médico Nacional 20 de Noviembre in Mexico City. All conventional-antagonist cycles were grouped according to their ovarian response and were evaluated from 2015 to 2020. Pearson's Squared-chi, Cramer's V, cross-table and the relative risk were calculated. RESULTS: The prevalence of premature progesterone rise oscillated from 20.8 to 67.9% for low and high ovarian responders, respectively. After calculating the relative risk, high ovarian responders had a 1.38 higher risk for premature progesterone rise than other groups. CONCLUSIONS: High ovarian responders have the highest risk for premature progesterone rise compared to normal and low ovarian responders. High ovarian responders have a 67.9% prevalence of premature progesterone rise.

Low ovarian responders produce more progesterone per follicle than normal and high responders.

OBJECTIVE: Late follicular premature progesterone rise is a complex phenomenon encountered during assisted reproductive technology (ART) treatments; different etiologies can occur in the same patient. Low ovarian responders may be the best example, since higher FSH doses and ovarian aging-related changes may interact and generate a premature progesterone rise. This study aims to explore the correlation between progesterone levels on hCG day and the progesterone-to-follicle index and compare the progesterone-to-follicle index according to ovarian response. METHODS: We performed a retrospective, observational, analytic, cross-sectional, and cohort study at the Reproductive Endocrinology Department at Centro Médico Nacional 20 de November between January 2015 to January 2020. After verifying for normalcy, a Spearman Rho, Principal Component Analysis, and a simple linear regression model were performed. Treatment cycles were classified according to their ovarian response. Low-ovarian responders were classified according to the Bologna Criteria. Then an ANOVA test was performed to compare each group. RESULTS: Our results show that the progesterone-to-follicle index correlates best with progesterone levels on hCG day. Comparing all the ovarian responses, low ovarian responders have the highest progesterone-to-follicle index of the four groups. CONCLUSIONS: Low ovarian responders produce more progesterone per follicle than regular and high responders.

Efficacy between Conventional Laparoscopy and Robotic Surgery in Mexican Patients with Endometriosis: A Comparative Study.

Background. Surgical management of endometriosis is essential, and deep endometriosis involves the invasion of endometrial tissue into other organs such as the bladder, ureters, and rectum. In Latin American countries, significant expertise has been achieved in conventional laparoscopy (CL); however, there is less experience in robot-assisted laparoscopy (RAL) because of the high cost of this technique. For this reason, studies comparing CL and RAL for the treatment of deep endometriosis in patients are scarce, making this study the first to share the experience of Mexican patients. Aim. The efficacy of CL vs. RAL in the management of deep endometriosis in Mexican patients was compared. Materials and Methods. We performed a retrospective and comparative study. We considered all patients treated with minimally invasive surgery for deep endometriosis between 2015 and 2023. Results. A total of 93 patients were included; 56 patients were treated with CL, and 37 patients were treated with RAL. A significant difference (p < 0.05) was observed in the postoperative length of stay, which was longer in patients treated with CL compared with those treated with RAL. Additionally, postoperative pain was less frequent in patients treated with RAL than in those treated with CL (p < 0.05). We did not observe a significant difference in operative time, blood loss, or perioperative complications between the two surgical techniques (p < 0.05). Conclusions. CL and RAL are effective methods for managing endometriosis in Mexican patients; however, RAL is beneficial for the treatment of deep endometriosis because patients experience postoperative pain less frequently than CL patients and have a shorter postoperative length of stay.

Antioxidant and molecular chaperone defences during estivation and arousal in the South American apple snail Pomacea canaliculata.

The invasive Pomacea canaliculata estivates during periods of drought and should cope with harmful effects of reoxygenation during arousal. We studied thiobarbituric acid reactive substances (TBARS), enzymatic (superoxide dismutase, SOD and catalase, CAT) and non-enzymatic antioxidants (uric acid and reduced glutathione), and heat shock protein expression (Hsc70, Hsp70 and Hsp90) in (1) active control snails, (2) snails after 45 days of estivation, and (3) aroused snails 20 min and (4) 24 h after water exposure, in midgut gland, kidney and foot. Both kidney and foot (but not the midgut gland) showed a TBARS increase during estivation and a decrease after arousal. Tissue SOD and CAT did not change in any experimental groups. Uric acid increased during estivation in all tissues, and it decreased after arousal in the kidney. Allantoin, the oxidation product of uric acid, remained constant in the midgut gland but it decreased in the kidney until 20 min after arousal; however, allantoin levels rose in both kidney and foot 24 h after arousal. Reduced glutathione decreased during estivation and arousal, in both midgut gland and kidney, and it remained constant in the foot. Hsc70 and Hsp70 kidney levels were stable during the activity-estivation cycle and Hsp90 expression decreases during estivation and recovers in the early arousal. In foot, the expression of Hsp70 and Hsp90 was high during activity and estivation periods and disminished after arousal. Results indicate that a panoply of antioxidant and molecular chaperone defences may be involved during the activity-estivation cycle in this freshwater gastropod.

Multicellular spheroid formation and evolutionary conserved behaviors of apple snail hemocytes in culture.

A hemocyte primary culture system for Pomacea canaliculata in a medium mimicking hemolymphatic plasma composition was developed. Hemocytes adhered and spread onto culture dish in the first few hours after seeding but later began forming aggregates. Time-lapse video microscopy showed the dynamics of the early aggregation, with cells both entering and leaving the aggregates. During this period phagocytosis occurs and was quantified. Later (>4 h), hemocytes formed large spheroidal aggregates that increased in size and also merged with adjacent spheroids (24-96 h). Large single spheroids and spheroid aggregates detach from the bottom surface and float freely in the medium. Correlative confocal, transmission electron and phase contrast microscopy showed a peculiar organization of the spheroids, with a compact core, an intermediate zone with large extracellular lacunae and an outer zone of flattened cells; also, numerous round cells emitting cytoplasmic extensions were seen attaching to the spheroids' smooth surface. Dual DAPI/propidium iodide staining revealed the coexistence of viable and non-viable cells within aggregates, in varying proportions. DNA concentration increased during the first 24 h of culture and stabilized afterward. BrdU incorporation also indicated proliferation. Spontaneous spheroid formation in culture bears interesting parallels with spheroidal hemocyte aggregates found in vivo in P. canaliculata, and also with spheroids formed by tumoral or non-tumoral mammalian cells in vitro.

Proteomic analysis of digestive tract peptidases and lipases from the invasive gastropod Pomacea canaliculata.

BACKGROUND: The invasive gastropod Pomacea canaliculata has received great attention in the last decades as a result of its negative impact on crops agriculture, yet knowledge of their digestive physiology remains incomplete, particularly the enzymatic breakdown of macromolecules such as proteins and lipids. RESULTS: Discovery proteomics revealed aspartic peptidases, cysteine peptidases, serine peptidases, metallopeptidases and threonine peptidases, as well as acid and neutral lipases and phospholipases along the digestive tract of P. canaliculata. Peptides specific to peptidases (139) and lipases (14) were quantified by targeted mass spectrometry. Digestion begins in the mouth via diverse salivary peptidases (nine serine peptidases; seven cysteine peptidases, one aspartic peptidase and 22 metallopeptidases) and then continues in the oesophagus (crop) via three luminal metallopeptidases (Family M12) and six serine peptidases (Family S1). Downstream, the digestive gland provides a battery of enzymes composed of aspartic peptidase (one), cysteine peptidases (nine), serine peptidases (12) and metallopeptidases (24), including aminopeptidases, carboxypeptidases and dipeptidases). The coiled gut has M1 metallopeptidases that complete the digestion of small peptides. Lipid extracellular digestion is completed by triglyceride lipases. CONCLUSION: From an integrative physiological and anatomical perspective, P. canaliculata shows an unexpected abundance and diversity of peptidases, which participate mainly in extracellular digestion. Moreover, the previously unknown occurrence of luminal lipases from the digestive gland is reported for the first time. Salivary and digestive glands were the main tissues involved in the synthesis and secretion of these enzymes, but plausibly the few luminally exclusive peptidases are secreted by ventrolateral pouches or epithelial unicellular glands. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Pathogenesis of an experimental mycobacteriosis in an apple snail.

In this work, we aimed at investigating cell and tissue responses of the apple snail Pomacea canaliculata, following the inoculation of the zoonotic pathogen Mycobacterium marinum. Different doses were tested (10, 20, 65, and 100 M CFU) and the mortality rate was negligible. The histopathogenesis was followed at 4, 9, and 28 days after inoculation. Overt histopathological lesions were consistently observed after the two largest doses only. In the lung, marked hemocyte aggregations, including intravascular nodule formation, were observed within the large blood veins that run along the floor and roof of this organ. Hemocyte aggregations were found occluding many of the radial sinuses supplying the respiratory lamina. Acid-fast bacilli were contained in the different hemocyte aggregations. In addition, hemocytes were observed infiltrating the storage tissue, which makes up most of the lung wall, and the connective tissue of the mantle edge. Additionally, signs of degradation in the storage tissue were observed in the lung wall on day 28. In the kidney, nodules were formed associated with the constitutive hemocyte islets and with the subpallial hemocoelic space, in whose hemocytes the acid-fast structures were found. Electron microscopy analysis revealed the presence of bacteria-containing phagosomes within hemocytes located in the surface zone of the islets. Additionally, electron-dense spheroidal structures, which are likely remnants of digested mycobacteria, were observed in close proximity to the hemocytes' nuclei. The size attained by the hemocyte nodules varied during the observation period, but there was no clear dependence on dose or time after inoculation. Nodules were also formed subpallially. Some of these nodules showed 2-3 layers with different cellular composition, suggesting they may also form through successive waves of circulating cells reaching them. Nodular cores, including those formed intravascularly in the lung, would exhibit signs of hemocyte dedifferentiation, possibly proliferation, and death. Hemocyte congestion was observed in the hemocoelic spaces surrounding the pallial ends of the renal crypts, and the renal crypts themselves showed de-epithelization, particularly on day 28. The diverse cellular responses of P. canaliculata to M. marinum inoculation and the high resilience of this snail to the pathogen make it a suitable species for studying mycobacterial infections and their effects on cellular and physiological processes.

Daily Oxygenation Support for Patients Hospitalized With SARS-CoV-2 in an Integrated Health System.

BACKGROUND: Many COVID-19 studies are constructed to report hospitalization outcomes, with few large multi-center population-based reports on the time course of intra-hospitalization characteristics, including daily oxygenation support requirements. Comprehensive epidemiologic profiles of oxygenation methods used by day and by week during hospitalization across all severities are important to illustrate the clinical and economic burden of COVID-19 hospitalizations. METHODS: This was a retrospective, multi-center observational cohort study of 15,361 consecutive hospitalizations of patients with COVID-19 at 25 adult acute care hospitals in Texas participating in the Society of Critical Care Medicine Discovery Viral Respiratory Illness Universal Study COVID-19 registry. RESULTS: At initial hospitalization, the majority required nasal cannula (44.0%), with an increasing proportion of invasive mechanical ventilation in the first week and particularly the weeks to follow. After 4 weeks of acute illness, 69.9% of adults hospitalized with COVID-19 required intermediate (eg, high-flow nasal cannula, noninvasive ventilation) or advanced respiratory support (ie, invasive mechanical ventilation), with similar proportions that extended to hospitalizations that lasted ≥ 6 weeks. CONCLUSIONS: Data representation of intra-hospital processes of care drawn from hospitals with varied size, teaching and trauma designations is important to presenting a balanced perspective of care delivery mechanisms employed, such as daily oxygen method utilization.

A study of chlorophyll-like and phycobilin pigments in the C endosymbiont of the apple-snail pomacea canaliculata.

Pigments present in the brown-greenish C morph of an intracellular endosymbiont of Pomacea canaliculata were investigated. Acetone extracts of the endosymbiotic corpuscles showed an absorption spectrum similar to that of chlorophylls. Three fractions obtained from silica gel column chromatography of the acetone extracts (C(I), C(II), and C(III)), were studied by positive ion fast atom bombardment-mass spectrometry (FAB-MS) and hydrogen-nuclear magnetic resonance (H-NMR). Results indicated the presence of (1) a sterol in the yellow colored C(I) fraction; (2) a mixture ofpheophorbides a and b in the major green fraction, C(II); and (3) a modified pheophorbide a in the smaller green fraction, C(III). Aqueous extracts of the C endosymbiont did not show evidence of the occurrence of C-phycocyanin, allophycocyanin or phycoerithrin (light absorption, fluorescence emission, and electrophoresis of the protein moieties) while cyanobacterial cells (Nostoc sp.) showed evidence of C-phycocyanin and allophycocyanin. The possible phylogenetic and functional significance of the pigments present in the C endosymbiont is discussed.

A Dissenters' View on AppleSnail Immunobiology.

We stand as dissenters against the acceptance of scientific knowledge that has not been built on empirical data. With this in mind, this review synthesizes selected aspects of the immunobiology of gastropods and of apple snails (Ampullariidae) in particular, from morphological to molecular and "omics" studies. Our trip went through more than two centuries of history and was guided by an evo-devo hypothesis: that the gastropod immune system originally developed in the mesenchymal connective tissue of the reno-pericardial complex, and that in that tissue some cells differentiated into hematopoietically committed progenitor cells that integrate constitutive hemocyte aggregations in the reno-pericardial territory, whether concentrated in the pericardium or the kidney in a species-specific manner. However, some of them may be freed from those aggregations, circulate in the blood, and form distant contingent aggregations anywhere in the body, but always in response to intruders (i.e., pathogens or any other immune challenge). After that, we reviewed the incipient immunology of the Ampullariidae by critically revising the findings in Pomacea canaliculata and Marisa cornuarietis, the only ampullariid species that have been studied in this respect, and we attempted to identify the effectors and the processes in which they are involved. Particularly for P. canaliculata, which is by far the most studied species, we ask which hemocytes are involved, in which tissues or organs are integrated, and what cellular reactions to intruders this species has in common with other animals. Furthermore, we wondered what humoral factors could also integrate its internal defense system. Among the cellular defenses, we give an outstanding position to the generation of hemocyte nodules, which seems to be an important process for these snails, serving the isolation and elimination of intruders. Finally, we discuss hematopoiesis in apple snails. There have been contrasting views about some of these aspects, but we envision a hematopoietic system centered in the constitutive hemocyte islets in the ampullariid kidney.

Enzymatic poly(gallic acid)-grafted α-l-lysine inhibits Staphylococcus aureus and Escherichia coli strains with no cytotoxicity for human cells.

The α-l-Lysine (LL) grafting onto the enzymatic poly(gallic acid) (PGAL) produces a helicoidal brush-like antimicrobial polymer containing outer positive-charged moieties. Best results are found with ca. 16 mol% α-LL-grafting for the inhibition of gram-positive Staphylococcus aureus and gram-negative Escherichia coli strains. Membrane permeability, confocal and scanning electron microscopy studies suggest a pore-formation and translocation mechanisms by initial electrostatic interaction of positive charged polymer at the negatively charged bacterial membranes. The attained polymer displays high concentration of hemolysis (Hc) in erythrocytes, and no lymphocyte mitochondrial activity. Interestingly, PGAL-LL is not cytotoxic on human dermal fibroblast. The antioxidant activity after the LL hybridization is also demonstrated by DPPH, ORAC, FRAP and hydroxyl radical scavenging, which enhances the preservation of human cells in addition to antimicrobial for this polymer.

Novel insights on premature progesterone elevation: a mini-review.

In vitro fertilization (IVF) success involves ovarian stimulation with conventional or mild stimulation protocols aimed to yield an adequate number of mature oocytes. These oocytes can be further fertilized and generate good quality embryos to be transferred, ideally in the same cycle. Since 2013, following the results of a meta-analysis including more than 60,000 IVF cycles, the negative effects of premature progesterone elevation on reproductive outcomes have been demonstrated. Nowadays, evidence is emerging on the limited regulation on serum progesterone values, demonstrating significantly lower live birth rates in patients with either low (<0.5ng/ml) late follicular phase progesterone or higher levels decreasing sharply. This review discusses and summarizes the different mechanisms of progesterone elevation and its impact on IVF treatments. Different approaches to diminish the impact of progesterone on fertility outcomes are also addressed.