Unraveling the Intricacies of the Seminal Microbiome and Its Impact on Human Fertility.

Although the microbial communities from seminal fluid were an unexplored field some decades ago, their characteristics and potential roles are gradually coming to light. Therefore, a complex and specific microbiome population with commensal niches and fluctuating species has started to be revealed. In fact, certain clusters of bacteria have been associated with fertility and health, while the outgrowth of several species is potentially correlated with infertility indicators.

The courtship choreography of homologous chromosomes: timing and mechanisms of DSB-independent pairing.

Meiosis involves deep changes in the spatial organisation and interactions of chromosomes enabling the two primary functions of this process: increasing genetic diversity and reducing ploidy level. These two functions are ensured by crucial events such as homologous chromosomal pairing, synapsis, recombination and segregation. In most sexually reproducing eukaryotes, homologous chromosome pairing depends on a set of mechanisms, some of them associated with the repair of DNA double-strand breaks (DSBs) induced at the onset of prophase I, and others that operate before DSBs formation.

A transcriptomic insight into the human sperm microbiome through next-generation sequencing.

The purpose of this study is to provide novel information through Next Generation Sequencing (NGS) for the characterization of viral and bacterial RNA cargo of human sperm cells from healthy fertile donors. For this, RNA-seq raw data of poly(A) RNA from 12 sperm samples from fertile donors were aligned to microbiome databases using the GAIA software. Species of viruses and bacteria were quantified in Operational Taxonomic Units (OTU) and filtered by minimal expression level (>1% OTU in at least one sample).

The impact of chromosomal fusions on 3D genome folding and recombination in the germ line.

The spatial folding of chromosomes inside the nucleus has regulatory effects on gene expression, yet the impact of genome reshuffling on this organization remains unclear. Here, we take advantage of chromosome conformation capture in combination with single-nucleotide polymorphism (SNP) genotyping and analysis of crossover events to study how the higher-order chromatin organization and recombination landscapes are affected by chromosomal fusions in the mammalian germ line. We demonstrate that chromosomal fusions alter the nuclear architecture during meiosis, including an increased rate of heterologous interactions in primary spermatocytes, and alterations in both chromosome synapsis and axis length.

Sperm microRNA pairs: new perspectives in the search for male fertility biomarkers.

Objective: To identify candidates of fertility biomarkers among pairs of human sperm microRNAs.

Design: Expression data of 736 sperm microRNAs from fertile and infertile individuals characterized in previous published studies by means of TaqMan quantitative polymerase chain reaction (PCR) were reexamined. A set of microRNA pairs with the best biomarker potential were selected and validated by means of quantitative real-time (qRT) PCR in an independent cohort.

The use of fluorescence in situ hybridization analysis on sperm: indications to perform and assisted reproduction technology outcomes.

Purpose: To determine the consequences of an altered sperm fluorescence in situ hybridization (FISH) result for ART outcomes and the indications for a sperm FISH analysis.

Methods: Data from 439 infertile men were collected. Bivariate analyses were performed to determine the association of men's age, seminal alterations, and sperm FISH indication, with the incidence of X, Y, 13, 18, and 21 sperm chromosomal abnormalities.

Chromosome positioning and male infertility: it comes with the territory.

The production of functional spermatozoa through spermatogenesis requires a spatially and temporally highly regulated gene expression pattern, which in case of alterations, leads to male infertility. Changes of gene expression by chromosome anomalies, gene variants, and epigenetic alterations have been described as the main genetic causes of male infertility. Recent molecular and cytogenetic approaches have revealed that higher order chromosome positioning is essential for basic genome functions, including gene expression.

Altered bivalent positioning in metaphase I human spermatocytes from Robertsonian translocation carriers.

Purpose: The study aims to determine whether there is an altered bivalent positioning in metaphase I human spermatocytes from Robertsonian translocation carriers.

Methods: Metaphase I human spermatocytes from three 45,XY,der(13;14)(q10;q10) individuals and a 45,XY,der(14;15)(q10;q10) individual were analyzed. Proximity relationships of bivalents were established by analyzing meiotic preparations combining Leishman staining and multiplex-FISH procedures.

Meiotic abnormalities in metaphase I human spermatocytes from infertile males: frequencies, chromosomes involved, and the relationships with polymorphic karyotype and seminal parameters.

The aim of this study was to look in depth at the relationship between meiotic anomalies and male infertility, such as the determination of the chromosomes involved or the correlation with patient features. For this purpose, a total of 31 testicular tissue samples from individuals consulting for fertility problems were analyzed. Metaphase I cells were evaluated using a sequential methodology combining Leishman stained procedures and multiplex fluorescence in situ hybridization protocols.

Chromosome size, morphology, and gene density determine bivalent positioning in metaphase I human spermatocytes.

Objective: To determine whether there is a preferential bivalent distribution pattern in metaphase I human spermatocytes and to analyze whether this positioning is influenced by chiasmata count, chromosome size, gene density, acrocentric morphology, and heterochromatic blocks.

Design: Proximity frequencies of bivalents were evaluated with the analysis of meiotic preparations combining sequentially standard techniques and multiplex fluorescence in situ hybridization.

Setting: University.

A sequential methodology that allows apoptotic cell sorting and FISH analysis in human testicular cells.

The objective of this study was to develop a methodology that permits the detection and separation of apoptotic cells in human testicular tissue and their subsequent cytogenetic analysis by fluorescence in situ hybridization (FISH). The sequential methodology consisted of five steps: 1) enzymatic disaggregation of testicular tissue, 2) specific staining of apoptotic cells, 3) cell sorting by flow cytometry, 4) cell fixation, and 5) FISH. Enzymatic disaggregation yielded cell counts that ranged from 1.

Acrocentric bivalents positioned preferentially nearby to the XY pair in metaphase I human spermatocytes.

Objective: To analyze whether the preferential proximity between acrocentric bivalents and the XY pair described at pachytene was maintained in metaphase I human spermatocytes.

Design: Proximity frequencies of autosomic bivalents to the sex bivalent were evaluated with the analysis of meiotic preparations combining sequentially standard techniques and multiplex fluorescence in situ hybridization.

Setting: Assisted reproduction centers.

Fluorescence in situ hybridization (FISH) protocol in human sperm.

Aneuploidies are the most frequent chromosomal abnormalities in humans. Most of these abnormalities result from meiotic errors during the gametogenic process in the parents. In human males, these errors can lead to the production of spermatozoa with numerical chromosome abnormalities which represent an increased risk of transmitting these anomalies to the offspring.

Role of sperm fluorescent in situ hybridization studies in infertile patients: indications, study approach, and clinical relevance.

Objective: To determine the group of infertile patients that would benefit from sperm fluorescent in situ hybridization (FISH) analysis, the number of chromosomes to be analyzed, and the diagnostic interpretation of the results obtained.

Design: A retrospective study of sperm FISH analyses.

Setting: Universitat Autònoma de Barcelona.

FISH on sperm: spot-counting to stop counting? Not yet.

Objective: To evaluate the reliability and applicability of the spot-counting system (Cytovision Spot AX workstation) which offers an alternative to the tedious manual analysis of sperm fluorescence in situ hybridization (FISH).

Design: Manual and automatic analyses were performed and compared.

Setting: Universitat Autònoma de Barcelona.

FISH studies of chromosome abnormalities in germ cells and its relevance in reproductive counseling.

Chromosome abnormalities are one of the major causes of human infertility. In infertile males, abnormal karyotypes are more frequent than in the general population. Furthermore, meiotic disorders affecting the germ cell-line have been observed in men with normal somatic karyotypes consulting for infertility.

Identification of meiotic anomalies with multiplex fluorescence in situ hybridization: Preliminary results.

Objective: To characterize meiotic anomalies in infertile men by multiplex fluorescence in situ hybridization (M-FISH) and to determine whether synaptic problems affect specific bivalents or whether anomalies are random.

Design: Analysis of meiotic preparations with standard techniques and M-FISH.

Setting: Assisted reproduction centers and Universitat Autònoma de Barcelona.