PRESS-NEWS.org - Press Release Distribution
PRESS RELEASES DISTRIBUTION

Reproductive biologists move in vitro fertilization knowledge forward

2 new papers from reproductive biologists at UMass Amherst report advances in understanding the basic processes of sperm capacitation that may one day improve IVF success by bypassing early problems, and may lead to a male contraceptive

2013-10-28
(Press-News.org) Contact information: Janet Lathrop
jlathrop@admin.umass.edu
413-545-0444
University of Massachusetts at Amherst
Reproductive biologists move in vitro fertilization knowledge forward 2 new papers from reproductive biologists at UMass Amherst report advances in understanding the basic processes of sperm capacitation that may one day improve IVF success by bypassing early problems, and may lead to a male contraceptive

AMHERST, Mass. – Two new papers from reproductive biologists at the University of Massachusetts Amherst, with international partners, report advances in understanding the basic processes of sperm capacitation that may one day improve success rates of in vitro fertilization (IVF) by providing a shortcut to bypass problems, and may eventually lead to a male contraceptive.

A "pill for men" may be a long way down the road, says Pablo Visconti, lead UMass Amherst author, but this new fundamental knowledge of how sperm acquire the ability to fertilize an egg, letting scientists either block or enhance the process, is at the heart of being able to control it. Findings by the international research teams appear in early online editions this month of Proceedings of the National Academy of Sciences (PNAS) and the Journal of Biological Chemistry (JBC), which named one study a finalist for "Paper of the Week."

As Visconti recalls, it was the discovery in the 1950s of sperm capacitation that made IVF possible. Sperm are not fertile until they spend time in the specialized environment of the female reproductive tract, moving through a series of biochemically delicate stages known as capacitation. In the past 50 years it has become clear not only that this signal transduction cascade for capacitation involves many stages, but that each mammalian species has its own different and specific requirements for success.

That is, IVF requirements are not universal, and species-specific requirements need to be established on a case-by-case approach. Visconti says there is great interest in using IVF in horses, for example, but despite years of research this is prohibitively difficult because too little is known about requirements for sperm capacitation in horses. Many biologists are also interested now in using IVF to help preserve endangered species, but the hurdles are immense because each requires very specific procedures, the biochemist adds.

Any better understanding of the cascade of events, where mistakes in IVF often occur, would be useful, Visconti says. Conducting experiments with mouse sperm in vitro, he and colleagues at UMass Amherst, with others at Weill Cornell Medical College, University of Hawaii Medical School, Asahikawa Medical University Japan, Universidad Nacional de Rosario and Facultad de Medicina Argentina and Universidad Nacional Autónoma de México made two discoveries that should help.

In the PNAS study, the researchers experimented with increasing intracellular calcium using the calcium ionophore, A23187. Calcium is known to play a role late in the sperm capacitation process, after many earlier steps in pathways that depend on soluble adenylyl cyclase, cyclic adenosine monophosphate (cAMP), protein kinase A (PKA) and other enzyme cascades have taken place.

A major drawback of adding calcium ionophore, however, is that it overwhelms the sperm with too much and quickly immobilizes them, Visconti notes. But he and colleagues found that they could get around this by simply washing the excess away. Thus they basically bypass early capacitation stages by applying the calcium ionophore, wash it away, and the sperm proceed with capacitation.

Under these conditions, the authors report, ionophore-treated sperm fertilized 80 percent of eggs, which developed into normal offspring. Their data indicate that ionophore-treated mouse sperm can fertilize ova even when the cAMP/PKA signaling pathway is inhibited.

Visconti credits his co-authors Hiroyuki Tateno in Japan and Ryuzo Yanagimachi in Hawaii with the idea of washing ionophore away after use. He points out, "Until they conceived it, no one had thought of this trick. They did the first experiments," Visconti explains. "Later, our experiments demonstrated that by treating the sperm with calcium ionophore, we were activating these cells far downstream of the normal biological process. And when the ionophore is washed away, the sperm retain just the calcium they need. They self-regulate the optimal calcium concentration and are ready to go on."

He adds, "Our laboratory is mainly interested in the basic science of how sperm acquire fertilizing capacity, but one interesting idea here is that this shortcut offers some translational possibilities for calcium ionophore use in IVF. This shortcut may address many of the difficult situations we encounter in IVF, in many species."

In the JBC finalist for "Paper of the Week," Visconti and colleagues including Ana Maria Salicioni address a long-standing question about the presence or not of transmembrane adenylyl cyclases in the highly compartmentalized sperm head and tail and their functional pathways.

Salicioni says, "We show that the rules for producing cAMP in head and tail are different and the targets are different. The main target in the tail is PKA. In the head the target is not clear yet, but it certainly is not PKA. So the cAMP pathways in head and tail are completely different, which is entirely new."

Using biochemical analysis methods in knockout mice, Visconti and colleagues show that while the soluble adenylyl cyclase (sAC) is present in the tail, transmembrane adenylyl cyclases (tmAC) are present in the head sperm compartment. These enzymes are involved in the synthesis of cAMP and, unexpectedly, the signaling pathways using this second messenger are different in the head and tail.



INFORMATION:



ELSE PRESS RELEASES FROM THIS DATE:

Bumps in the road to developing long-lasting, single-injection nerve blocks

2013-10-28
Bumps in the road to developing long-lasting, single-injection nerve blocks A study of liposomal bupivacaine gives encouraging -- but puzzling -- results San Francisco, CA. (October 28, 2013) – Can a new liposomal bupivacaine product provide long-lasting ...

Study of Brazilian Amazon shows 50,000 km of road was built in just 3 years

2013-10-28
Study of Brazilian Amazon shows 50,000 km of road was built in just 3 years Nearly 17,000 kilometres of road were built in the Brazilian Amazon rainforest every year between 2004 and 2007. Although road-building is a major contributor to deforestation ...

Climate change has silver lining for grizzlies

2013-10-28
Climate change has silver lining for grizzlies Global warming and forest disturbances may have a silver lining for threatened species of grizzly bears in Alberta, Canada. In a 10-year study that monitored 112 bears in Alberta's Rocky Mountain region, University ...

Untangling Alzheimer's disease

2013-10-28
Untangling Alzheimer's disease Tel Aviv University researchers identify specific molecules that could be targeted to treat the disorder Plaques and tangles made of proteins are believed to contribute to the debilitating progression of Alzheimer's disease. ...

First ever study of 'moral distress' among nurses in burn unit

2013-10-28
First ever study of 'moral distress' among nurses in burn unit MAYWOOD, Il. – Loyola University Medical Center researchers have published the first ever study of emotional and psychological anguish, known as "moral distress," experienced by nurses in an intensive ...

Quantum reality more complex than previously thought

2013-10-28
Quantum reality more complex than previously thought Imagine you order a delivery of several glass vases in different colors. Each vase is sent as a separate parcel. What would you think of the courier if the parcels arrive apparently undamaged, ...

Excess omega-3 fatty acids could lead to negative health effects

2013-10-28
Excess omega-3 fatty acids could lead to negative health effects CORVALLIS, Ore. – A new review suggests that omega-3 fatty acids taken in excess could have unintended health consequences in certain situations, and that dietary standards based on the best ...

Child brides at funerals

2013-10-28
Child brides at funerals Young maternal age and quick pregnancies linked to high infant mortality in South Asia Having children early and in rapid succession are major factors fueling high infant mortality rates in the South Asian countries of Bangladesh, ...

UC develops unique nano carrier to target drug delivery to cancer cells

2013-10-28
UC develops unique nano carrier to target drug delivery to cancer cells A unique nanostructure developed by a team of international researchers, including those at the University of Cincinnati, promises improved all-in-one detection, diagnoses and drug-delivery ...

Overlooked lymph nodes in rib cage have prognostic power for mesothelioma patients

2013-10-28
Overlooked lymph nodes in rib cage have prognostic power for mesothelioma patients SYDNEY, AUSTRALIA—For the first time, researchers from the Perelman School of Medicine at the University of Pennsylvania have shown the predictive power ...

LAST 30 PRESS RELEASES:

Small nuclear RNA base editing a safer alternative to CRISPR, UC San Diego researchers find

Can Hayabusa2 touchdown? New study reveals space mission’s target asteroid is tinier and faster than thought

Millisecond windows of time may be key to how we hear, study finds

Graz University of Technology opens up new avenues in lung cancer research with digital cell twin

Exoplanets are not water worlds

Study shows increasing ‘healthy competition’ between menu options nudges patients towards greener, lower-fat hospital food choices

New insights into melanoma plasticity uncover a critical role of iron metabolism

A graphene sandwich — deposited or transferred?

New light-powered motor fits inside a strand of hair

Oil rig study reveals vital role of tiny hoverflies

Children’s Hospital of Philadelphia researchers boost widespread use of dental varnish across pediatric network

iRECODE: A new computational method that brings clarity to single-cell analysis

New NUS-MOH study: Singapore’s healthcare sector carbon emissions 18% lower than expected, a milestone in the city-state’s net zero journey

QUT scientists create material to turn waste heat into clean power

Major new report sets out how to tackle the ‘profound and lasting impact’ of COVID-19 on cardiovascular health

Cosmic crime scene: White dwarf found devouring Pluto-like icy world

Major report tackles Covid’s cardiovascular crisis head-on

A third of licensed GPs in England not working in NHS general practice

ChatGPT “thought on the fly” when put through Ancient Greek maths puzzle

Engineers uncover why tiny particles form clusters in turbulent air

GLP-1RA drugs dramatically reduce death and cardiovascular risk in psoriasis patients

Psoriasis linked to increased risk of vision-threatening eye disease, study finds

Reprogramming obesity: New drug from Italian biotech aims to treat the underlying causes of obesity

Type 2 diabetes may accelerate development of multiple chronic diseases, particularly in the early stages, UK Biobank study suggests

Resistance training may improve nerve health, slow aging process, study shows

Common and inexpensive medicine halves the risk of recurrence in patients with colorectal cancer

SwRI-built instruments to monitor, provide advanced warning of space weather events

Breakthrough advances sodium-based battery design

New targeted radiation therapy shows near-complete response in rare sarcoma patients

Does physical frailty contribute to dementia?

[Press-News.org] Reproductive biologists move in vitro fertilization knowledge forward
2 new papers from reproductive biologists at UMass Amherst report advances in understanding the basic processes of sperm capacitation that may one day improve IVF success by bypassing early problems, and may lead to a male contraceptive