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Study maps bed bugs’ genomes in unprecedented detail to find out why they just won’t die
Scientists mapped near-gap-free and near-error-free genomes of a susceptible bed bug strain and a superstrain around 20,000 times more insecticide-resistant, offering the broadest look yet at the full scope of their resistance mutations.
Their findings were published in the journal Insects.
Although there is no evidence that bed bugs transmit diseases to humans, their bites can cause itchy rashes and secondary skin infections. Widespread use of insecticides, including the now-banned DDT, nearly wiped out populations of these blood-sucking insects by the 1960s, making infestations rare. But over the past 20 years, the world has witnessed their resurgence, partly due to resistance mutations they developed against these insecticides.
Resistance can occur through different mechanisms, such as by producing enzymes that detoxify the insecticides (metabolic resistance) or developing thicker outer layers to block the chemicals (penetration resistance). Past studies have identified some of the mutations and gene expressions linked to insecticide resistance. However, the full extent of mutations driving resistance remains unknown as no research has sequenced the whole genome of insecticide-resistant strains.
A research team led by Hidemasa Bono, professor at Hiroshima University’s (HU) Graduate School of Integrated Sciences for Life, mapped genomes of susceptible and resistant bed bug strains from Japan to address this gap. They obtained susceptible strains descended from wild bed bugs (Cimex lectularius) collected 68 years ago in fields at Isahaya City, Nagasaki.
Meanwhile, the resistant strains were bred from specimens collected from a Hiroshima City hotel in 2010. Their tests revealed that the resistant samples had 19,859-fold stronger resistance to pyrethroids—the most commonly used insecticide for bed bug control—exceeding levels seen in many previously identified superstrains. All the specimens were provided by Fumakilla Limited, a Japan-based chemical manufacturing company.
Piecing together the genome puzzle
Sequencing a genome is like assembling a massive jigsaw puzzle, spanning anywhere from about 160,000 to 160 billion pieces. To map the most complete bed bug genomes to date, researchers used the breakthrough method of long-read sequencing, which captures longer stretches of DNA—akin to having entire sections of puzzle pieces put together. Traditional short-read sequencing, by contrast, only covers tiny snippets, often leading to frustrating gaps.
The researchers assembled a near-total picture of the two genomes with just about every piece precisely where it belonged, achieving 97.8% completeness and quality value (QV) of 57.0 for the susceptible strain and 94.9% completeness and QV of 56.9 for the resistant strain. A QV above 30 indicates high-quality sequences with less than a 0.1% error rate. Both also surpassed the N50 value of the existing C. lectularius reference genome, Clec2.1, from a previous sequencing effort, meaning there were fewer gaps and more complete sections of the genome puzzle.
Known, new resistance mutations uncovered
After fully sequencing the genomes, the team identified protein-coding genes, determined their functions, and assessed if they were active through transcriptional analysis. They uncovered 3,938 transcripts with amino acid mismatches. Of these, 729 mutated transcripts were linked to insecticide resistance.
“We determined the genome sequence of insecticide-resistant bed bugs, which exhibited 20,000-fold greater resistance compared to susceptible bed bugs. By comparing the amino acid sequences between the susceptible and resistant bed bugs, we identified 729 transcripts with resistance-specific mutations,” said study first author Kouhei Toga, postdoctoral researcher at the Laboratory of Genome Informatics of HU’s Graduate School of Integrated Sciences for Life.
“These transcripts included genes related to DNA damage response, cell cycle regulation, insulin metabolism, and lysosome functions. This suggests that these molecular pathways may play a role in the development of pyrethroid resistance in bed bugs.”
By drawing on previous insect studies, the researchers confirmed known resistance mutations and discovered new ones that could inform more targeted and effective pest control strategies.
“We identified a large number of genes likely involved in insecticide resistance, many of which have not been previously reported as being associated with resistance in bedbugs. Genome editing of these genes could provide valuable insights into the evolution and mechanisms of insecticide resistance,” Toga said.
“Additionally, this study expands the pool of target genes for monitoring allele distribution and frequency changes, which could contribute significantly to assessing resistance levels in wild populations. This work highlights the potential of genome-wide approaches in understanding insecticide resistance in bed bugs.”
Other research team members include Fumiko Kimoto and Hiroki Fujii.
More information:
Kouhei Toga et al, Genome-Wide Search for Gene Mutations Likely Conferring Insecticide Resistance in the Common Bed Bug, Cimex lectularius, Insects (2024). DOI: 10.3390/insects15100737
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Hiroshima University
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Study maps bed bugs’ genomes in unprecedented detail to find out why they just won’t die (2024, December 17)
retrieved 22 December 2024
from https://phys.org/news/2024-12-bed-bugs-genomes-unprecedented-wont.html
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Arctic Siberia summers were up to 10°C warmer than today during the Last Interglacial, study finds
Interglacials are, as the name suggests, warm periods between planetary glaciations when the expanse of ice on Earth shrinks. Currently, we are in an 11,000 year-long interglacial period known as the Holocene. Prior to this, the Last Interglacial occurred between 115,000 and 130,000 years ago.
During this time, Earth experienced summers that were almost completely ice-free and there was significant vegetation growth in polar regions, changing the ecosystems for life to flourish. Scientists can look to this Last Interglacial as a potential analog for future global warming.
Indeed, new research, currently under review for publication in the Climate of the Past journal, has turned to the geological record of the Arctic to understand how terrestrial environments responded to the warmer world. Here, warming was amplified compared to the rest of the northern hemisphere due to ice albedo feedbacks, whereby solar insolation melted ice sheets, reducing the amount of radiation reflected back out to space and causing further warming, creating a positive feedback loop.
Dr. Lutz Schirrmeister, of the Helmholtz Center for Polar and Marine Research in Germany, and colleagues have turned to particular landscapes generated in areas experiencing permafrost, where the ground has remained frozen for at least two years.
Thermokarst topography is unique to such regions, characterized by hollows and hummocks that form when ice-rich permafrost thaws and the surface slumps due to a lack of ice in the pore spaces between sediments. Nowadays, these depressions also fill with water, producing thermokarst lakes.
Dr. Schirrmeister and the team investigated coastal sections along the Dmitry Laptev Strait, Siberia, via sediment cores drilled during fieldwork between 1999 and 2014, which preserve alternating layers of peaty plant matter with clays and silts. These distinctive layers represent the changing landscape through time between shallower boggy terrain where plants could grow, to deeper lake deposits. Today, the study area is a mixture of drier tundra with substantial plant growth, grasses and wetlands underlain by 400–600m of permafrost.
From these cores, the scientists used a combination of sediment analysis with fossil remains of plants (pollen, leaves and stems), insects (beetles and midges), crustaceans (ostracods) and animals (water fleas and mollusks) to reconstruct the paleoenvironment.
Combined with modeling, this data highlights that steppe or tundra-steppe (grassland and low-growing shrubs) environments prevailed in the area at the beginning of the Last Interglacial, but that birch and larch forests proliferated during the middle of the event, with the treeline being 270km north of its current position during the peak.
The researchers ultimately identified up to 10°C more summer warming in northern Siberia during the Last Interglacial compared to summers today, with fossilized plant material suggesting that mean temperatures of the warmest month could have reached 15°C, while fossil beetles indicate the coldest temperature may have been -38°C. Today, the respective mean temperatures are approximately 3°C and -34°C.
Having said this, in June 2020, the town of Verkhoyansk in Russia measured the highest temperature ever recorded above the Arctic Circle at 38°C, while the lowest temperature recorded is -69°C in Greenland. While these were anomalous, the continued changing climate highlights the need to look to the past to inform the future, when such conditions could become more common.
Dr. Schirrmeister notes that while the Last Interglacial warming mostly impacted summer temperatures, future climate change is expected to more broadly impact winter months due to anthropogenic activity. Nevertheless, ice sheet retreat, loss of sea ice and melting permafrost are all observed in the Arctic today, highlighting the importance of continued research into the sensitivity of Earth to rising temperatures during the Last Interglacial.
More information:
Lutz Schirrmeister et al, Newly dated permafrost deposits and their paleo-ecological inventory reveal a much warmer-than-today Eemian in Arctic Siberia, Climate of the Past (2024). DOI: 10.5194/cp-2024-74
© 2024 Science X Network
Citation:
Arctic Siberia summers were up to 10°C warmer than today during the Last Interglacial, study finds (2024, December 19)
retrieved 22 December 2024
from https://phys.org/news/2024-12-arctic-siberia-summers-10c-warmer.html
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part may be reproduced without the written permission. The content is provided for information purposes only.
I wouldn’t change first five months as PM, says Keir Starmer
House of CommonsSir Keir Starmer has insisted he would not do anything differently, as he came under fire from MPs over decisions in his first five months in office.
The prime minister defended changes to farmers’ inheritance tax, hikes to business taxes and cuts to winter fuel payments in 90 minutes of questions.
Labour “had to do tough stuff” to stabilise the public finances after being left an “awful” inheritance from the Conservatives, he said.
He insisted he was still committed to achieving the highest “sustained” growth among G7 countries by the next election.
But he warned it could “take some time” for people to feel better off, as he asked for patience on his plans to boost the economy.
It comes as the Bank of England said the economy had performed worse than expected, with no growth at all between October and December.
Sir Keir set the G7 growth target in early 2023, more than a year before his party returned to power at July’s general election.
Earlier this month, he announced an additional target to improve living standards, leading to some accusations he was moving the goalposts on what he wanted his government to be judged by.
But in his first appearance before the liaison committee of senior MPs since entering office, Sir Keir insisted he was still committed to getting the UK growing faster other G7 members, such as the US, Germany and Japan, by 2029.
When it was pointed out to him that economic forecasts suggested this was not going to happen, he said they had not taken some future policy changes into account.
He cited a rise to the legal minimum wage, announced at October’s Budget, as an example of how ministers were boosting living standards.
He added that changes to the planning system, other “regulations” and new technology such as artificial intelligence (AI) would also help improve the UK’s economic growth rates.
‘Position of power’
But the prime minister faced sustained questioning from the select committee chairs over policies decisions that have not gone down well with the opposition and, in some cases, his own MPs.
These include cuts to the winter fuel payment for pensioners, changes to farmers’ inheritance tax status, and freezing the amount of housing benefit that private renters can claim next year.
Asked by the committee’s Labour chair Meg Hillier whether he would do anything differently in his first months in power if he knew what he does now, Sir Keir replied: “No.”
“We had to do tough stuff, we’re getting on with it,” he added.
On life as prime minister, he said he was “pleased to be delivering from a position of power” rather than losing votes in the House of Commons “every night” in opposition.
Elsewhere in the liaison committee session:
- Sir Keir warned the UK must not “make the mistake” of assuming a future Syrian government is “necessarily going to be different and better” than that of ousted leader Bashar al-Assad
- He added he was “alive to the danger” of Donald Trump imposing tariffs on the UK when he takes office, but insisted they could be avoided
- He insisted his plans to negotiate an agreement with the EU on food safety rules did not rule out a future trade deal with the United States
Asked when people would feel better off as a result of his government’s policies, the PM said: “It will take some time, of course it will”.
“The planning will take time. The change in regulation will take time, we’ve got a national wealth fund which is investing, getting record investment into the country, that will take time.
“But already some of the lowest paid are already feeling the benefits of a Labour government through what we did in the Budget.”
Labour has complained of the inheritance it was left by the Conservatives, including a disputed £22bn “black hole” in spending plans for this year.
At the Budget it announced plans to raise taxes, including the amount of National Insurance paid by employers from next April.
Ministers have insisted the move was necessary to put the country’s finances on a firmer footing – but they have faced opposition criticism that the move will stymie efforts to boost the UK’s economic fortunes.
Archbishop of York ‘regrets’ that abuse scandal priest David Tudor was reappointed twice
Getty ImagesA Church of England priest at the centre of a sexual abuse case was twice reappointed to a senior role during the Archbishop of York’s time as Bishop of Chelmsford, the BBC can reveal.
A BBC investigation previously revealed how David Tudor remained in post nine years after Stephen Cottrell was first told of concerns about him.
New information shows Tudor’s contract as area dean in Essex was renewed in 2013 and 2018, at which times Mr Cottrell knew he had paid compensation to a woman who says she was abused by him as a child.
The Archbishop of York said he regrets his handling of the case, with a spokesperson saying “he acknowledges this could have been handled differently”.
They added that “all the risks around David Tudor were regularly reviewed” and that was the “main focus”.
The pressure on Mr Cottrell comes at a time of turmoil in the Church of England following a damning report into how it covered up prolific abuse by the barrister John Smyth.
The report led to the resignation of the Church’s most senior figure, Archbishop of Canterbury Justin Welby. Mr Cottrell will take over his role temporarily for a few months in the New Year.
Rachel Ford, who told the investigation she was groomed by Tudor as a child, said the renewal of his contract as area dean was “an insult to all of his victims”.
Ms Ford added that if responsibility for that lay with Mr Cottrell, it strengthened her feeling that he should resign.
The BBC investigation showed Mr Cottrell was briefed in his first week as Bishop of Chelmsford about serious safeguarding issues surrounding Tudor.
These included that Tudor was convicted of indecently assaulting three underage girls and was jailed for six months in 1988, although the conviction was quashed on technical grounds. Mr Cottrell would also have known Tudor served a five-year ban from ministry.
By 2012, Mr Cottrell also knew Tudor had paid a £10,000 settlement to a woman who says she was sexually abused by him from the age of 11. In 2018, the Church of England issued an apology and a six-figure pay-out to another alleged victim.
Yet the priest was suspended only in 2019 when a police investigation was launched after another woman came forward alleging Tudor had abused her in the 1980s.
Facebook/Canvey CofEWhen first responding to the BBC’s investigation, the Archbishop of York said he was “deeply sorry that we were not able to take action earlier”, insisting he had acted at the first opportunity that was legally available to him.
Mr Cottrell also said he had been faced with a “horrible and intolerable” situation and that it was “awful to live with and to manage”.
When Mr Cottrell became bishop in 2010, Tudor was into the second year of a five-year term as an area dean, a role overseeing 12 parishes in Essex.
His appointment to that post, under a different bishop, happened despite him working under a safeguarding agreement that barred him from being alone with children and entering schools.
The title was renewed twice under Mr Cottrell – in 2013 and 2018 – and he lost the title only when the term of office expired in 2020. It was not taken from him.
A spokesperson for the Archbishop said he “accepts responsibility for David Tudor remaining as area dean”.
“No-one advised him that David Tudor should not continue as an area dean,” said the Archbishop’s office.
Bishop of Newcastle Helen-Ann Hartley posted on X that Mr Cottrell’s expressions of regret did not “square” with his actions.
“I don’t know how you can find a situation ‘horrible and intolerable’ and then square that with what is reported here.
“Answer is, you can’t and be expected to be a credible voice as the leadership of the Church of England.”
The Reverend Lucy Winkett, Rector of St James’s Piccadilly, told the BBC that the Church’s credibility is “in serious trouble”.
“The credibility of the church, yes it’s in… we’re in serious trouble in terms of our credibility, but the job of the leaders in the church like me is to keep reminding ourselves who we’re here for”, she told BBC Radio 4’s The World This Weekend on Sunday.
The programme also spoke to the Bishop of Gloucester, the Right Reverend Rachel Treweek, who said she felt “shock and dismay” upon hearing the latest findings about the Archbishop of York.
Pushed for a direct answer on whether she supports Mr Cottrell’s role in Church, she said: “I want the proper process to take place, in order that we shape ourselves as the right sort of Church going forward, and that for me is the big question”.
Another of Tudor’s victims, who does not want to be identified, said she was “shocked and disappointed” to hear his tenure as area dean was twice renewed during Mr Cottrell’s time as Bishop of Chelmsford.
“These are not the actions of a bishop dealing with a situation that was intolerable to him, in fact, quite the opposite. I call on him to do the honourable thing for the sake of the Church and resign,” she says.
In 2015, under Mr Cottrell, Tudor was also made honorary canon of Chelmsford Cathedral.
The Archbishop’s office insisted it happened because of a change in Church policy during Mr Cottrell’s time as Bishop of Chelmsford, meaning area deans were automatically made honorary canons.
It was “not a promotion and not a personal reward”.
However, a social media post from Tudor’s Canvey Island parish in July 2015 suggests it was seen there as a reward.
Tudor’s “hard work, determination and commitment to this place have been recognised by the diocese and this new position in the Church is very well-deserved,” it said.
The BBC has also seen evidence – in leaked minutes from internal Church meetings in 2018 and 2019 – that Tudor’s titles of area dean and honorary canon were discussed and there had been a suggestion Mr Cottrell could immediately have taken them away.
In October 2018, a meeting at Church House – the London headquarters of the Church of England – heard that Chelmsford diocese took the view that if Tudor “can be a parish priest, he can undertake the other roles”.
A bishop from another diocese said “the Bishop of Chelmsford could remove DT’s [David Tudor’s] canon and area dean titles straight away”.
But in a follow-up discussion in November 2018, Chelmsford diocese advised it would not be appropriate because of “the difficulty of removing those titles without explaining why.”
We asked Mr Cottrell’s office why he had not followed the suggestion to remove Tudor’s titles. We were told “it would not be appropriate to comment on any notes or decisions from a core group process which are confidential”.
The investigation also highlighted the significant role played by former Archbishop of Canterbury George Carey in the case.
We revealed Lord Carey had agreed to Tudor’s return to priesthood after being suspended in 1989, and had also agreed to have Tudor’s name removed from the list of clergy that had faced disciplinary action. He had also advocated for the priest.
After the BBC put this information to the former Archbishop of Canterbury, he wrote to give up his “permission to officiate”, ending more than 65 years of ministry in the Church of England. Lord Carey made the announcement on Tuesday.
In October 2024, Tudor admitted sexual misconduct and was sacked by the Church. At no point has he responded to the BBC’s attempts to speak with him.
Leon Ruan: Hull KR sign former Leeds Rhinos forward on two-year deal
Hull KR have signed former Leeds Rhinos forward Leon Ruan on a two-year deal after a successful trial.
The 21-year-old spent time on loan with the Robins’ cross-city rivals Hull FC last season and was released by the Rhinos in October.
“I’m over the moon to be signing. The opportunity to come here was something I knew I had to grab with both hands and throw myself into,” he told the club website., external
“The trajectory of the club is something I’d love to be part of and I think this club is the best place to get the best out of me on the pitch.”