Háskóli Íslands
https://hdl.handle.net/20.500.11815/56
University of Iceland2024-03-29T13:27:51ZEpigenetic insights into the mammalian mild hypothermia response
https://hdl.handle.net/20.500.11815/4774
Epigenetic insights into the mammalian mild hypothermia response
Rafnsdóttir, Salvör
Þekkt er að kæling frumna (32-36°C) eykur tjáningu fáeinna þekktra gena. Margt
er á huldu um þá innanfrumu- og millifrumuferla sem kæling snertir við og
kallaðir hafa verið kælisvarið. Kæling er notuð í læknisfræðilegum tilgangi til að
fá fram taugaverndandi áhrif hjá sjúklingum sem hafa orðið fyrir miklum
taugaskaða, svo sem eftir hjartastopp eða vegna súrefnisþurrðar í fæðingu.
Kælivísar (mild hypothermia indicators (MHI)) voru búnir til en þeir segja til um
tjáningu þriggja gena (SP1, CIRBP, RBM3) sem þegar eru þekkt að því að gegna
hlutverki í kælisvarinu. Kælivísarnir voru nýttir við framkvæmd skimana fyrir
áhrifaþáttum kælisvarsins. Kælivísarnir sýna mestu svörunina við 32°C í
mismunandi frumulínum, og þeir hafa takmarkaða virkni við hátt hitastig (40°C)
og lágt hitastig (˂30°C), en þetta bendir til sértækni kælivísanna. Framkvæmdar
voru þrenns konar skimanir fyrir þáttum sem hafa áhrif á kælisvarið; lyfjaskimun,
CRISPR-Cas9-stökkbreytiskimun og ENU-stökkbreytiskimun. Auk þess var RNA-mengi
kældra og ókældra frumna úr músum raðgreint, bæði frá frumum úr heilum
lífverum og ræktuðum músafrumum.
Við framkvæmd skimana var SP1+MCRE-MHI kælivísirinn notaður í leit að virkjun
kælisvarsins meðal 1953 lyfja. Tvö lyf (Poziotinib og Entacapone) fundust sem
bæði virðast geta virkjað kælisvarið. Næst voru kælivísarnir, SP1-MHI og LentiRBM3-MHI, notaðir með framsýnni CRISPR-Cas9-stökkbreytiskimun til þess að
finna gen sem virkja eða bæla kælisvarið. Við fundum mörg gen sem virðast
geta virkjað eða bælt kælisvarið en eitt þeirra gena sem bælir kælisvarið,
SMYD5 skoðuðum við frekar. SMYD5 færir metýlhópa á histón sem gegnir
hlutverki í stjórnun genatjáningar. Utangenaerfðamerki eru þekktir miðlar
hitastigsáhrifa á erfðamengi í öðrum lífverum. Í óháðu gangasetti sést að við
37°C er SMYD5 bundið við stjórnraðir SP1 og CIRBP en ekki við stjórnröð RBM3.
Á sama stað og SMYD5 bindst við erfðamengið kemur H3K36me3
utangenaerfðamerkið fram. Ef SMYD5 er slegið út má sjá aukningu SP1 og
CIRBP við 37°C með próteinmagnmælingu og einnig sjáum við aukningu á
virkjun SP1-MHI kælivísins við 37°C og 32°C. SMYD5 minnkar við 32°C í
mannafrumum og heila músa ásamt SMYD5 bindingu við erfðamengið í
mannafrumum. Við framkvæmdum framsýna ENU stökkbreytiskimun á músum, til
þess að finna gen sem valda afbrigðilegri hitastigsstjórnun við kæliáreiti. Fyrstu
niðurstöður þeirrar skimunar lofar góðu og hafa listar verið birtir yfir þau gen
sem hugsanlega valda afbrigðilegri hitastigsstjórnun í lífverum.
v
Einnig var RNA raðgreining framkvæmd á taugastofnfrumum úr músum í rækt
við 37°C og 32°C, og frumum úr dreka ásamt heilaberki músa sem annars vegar
höfðu innra hitastig 37°C og hins vegar innra hitastig við 32°C. Í ljós kom að
mörg gen breyta tjáningu sinni við kælingu. Þrjátíu og sjö önnur gen fundust
sem SMYD5 virðist bæla við 37°C og haga sér því á svipaðan máta og SP1.
Þetta verkefni hefur aukið skilning á kælisvari spendýrafrumna, en mörg gen
breyta tjáningu sinni við kælingu eða hafa áhrif á grunnlíkamshitastig lífvera eftir
kælingu. Í þessari doktorsritgerð kemur fram hvernig kæling fyrir tilstuðlan
utangenaerfða, getur haft áhrif á genatjáningu. Einnig fundust tvö lyf sem
mögulega geta haft áhrif á kælisvörun, en það býður upp á frekari möguleika til
rannsókna á lyfjameðferðum hjá sjúklingum sem þurfa á kælimeðferð að halda.; In humans, the expression of several genes is increased with mild hypothermia
(32-36°C), however, the precise nature of this mild hypothermia response (MHR)
is unknown. In clinical practice MHR is often utilized as a neuroprotective agent
in catastrophic events such as after neonatal hypoxic ischemia and cardiac arrest.
In this thesis there were several methods used to gain deeper understanding of
some of the characteristics of the MHR. To study these effects there were created
and validated arrays of fluorescent mild hypothermia indicators (MHI) which
measure regulatory activity of three genes (SP1, CIRBP, RBM3) which have
previously been shown to be part of the MHR. The MHIs show maximum
activation at 32°C in diverse cell systems with limited response in hyperthermia
or moderate hypothermia (˂30°C), which indicates specificity. Here, three different
types of screens were performed; a drug screen, CRISPR-Cas9 KO (knock out)
mutagenesis screen and an ENU mutagenesis screen. RNA-Sequencing of in vivo
and in vitro mouse cells that had been exposed to hypothermia was also
performed.
To gain further insight into the MHR the MHIs were utilized for two of three
different screening strategies. The SP1+MCRE-MHI was used to look for MHR
activation after medication exposure to 1953 FDA-approved compounds. This
yielded two agents (Poziotinib and Entacapone) that could activate the MHR.
Next, a forward CRISPR-Cas9 mutagenesis screen was combined with two MHIs,
SP1-MHI and Lenti-RBM3-MHI, to identify a list of potential activators/repressors
of SP1 and RBM3. Which led to the identification of numerous activators and
repressors, including the repressor SMYD5 which was studied further. SMYD5 is
a histone methyltransferase known to play a role in gene regulation. In other
species, histone modifications as well as epigenetic regulators are used to
integrate temperature cues into regulatory networks. Independent datasets show
temperature (37°C) dependent SMYD5 binding at promoters of both SP1 and
CIRBP but not RBM3. At the site of SMYD5 genomic binding there is an
overlapping H3K36me3 modification peak. SMYD5 expression and genomic
binding decreases at 32°C in vivo and in vitro, as quantified by Western blotting,
CUT&RUN and Immunofluorescence. Next, a dominant ENU mutagenesis screen
was performed to look for genes that cause abnormality in core temperature
under hypothermic stimulus. The first results are promising, and this thesis
vii
provides a list of candidate genes that could cause core temperature
abnormality, although the list needs further validation.
RNA-Sequencing was performed of in vitro mouse Neural Progenitor cells
(mNPCs) at 37°C and 32°C as well as RNA-sequencing of in vivo mouse
hippocampal and cortical cells that had their core temperature either kept at
37°C or lowered to 32°C. There are many genes that have altered expression
under hypothermic conditions. A list of additional 37 temperature responsive
genes were identified; these genes seem to be regulated in a similar
temperature dependent manner as SP1 and CIRBP by SMYD5.
This project expands the current knowledge of the mild hypothermia pathway in
mammalian cells and mammals. Here in this thesis, there is a mammalian
example provided of how the epigenetic machinery incorporates the influence of
environmental cues into the genome of mammalian cells. Also, potential novel
therapeutic avenues for targeted temperature management/therapeutic
hypothermia are identified.
2024-04-05T00:00:00ZPokot Masculinity: The Role of Rituals in Forming Men
https://hdl.handle.net/20.500.11815/4772
Pokot Masculinity: The Role of Rituals in Forming Men
Jónsson, Kjartan
ABSTRACT
This thesis is a contribution to masculinity studies, and is a case study about the world of Pokot men in Kenya. In it I try to answer the questions: How do the rituals Pokot men go through from birth to death, the age-set system, and the male institutions, war and the cattle exchange system, tïlya, shape their identity? Which values do they transmit? What are the specific values of Pokot men? How do they internalize them? At the beginning the Pokot people are put into a wider African context, as a part of the big Nilotic group of peoples and the Kalenjin sub-group. It is argued that this people group is young in the present form, probably from the second half of the 19th century, and further that it is a mixture of the primordial Okiek group, called Cherangany, and their neighbors. To better understand the rituals men go through, they are put into the context of the Pokot religion, which main elements are described, and of African traditional religion. As babies men go through the “plant the spirit” ritual in which an ancestral spirit in the family becomes a part of the baby as a guardian spirit. In order to become mature men and full members of the society boys are circumcised and initiated into the secrets of the elders. They stay for three and a half months in an initiation camp where they go through several stages and rituals and have to endure great hardship to become good soldiers. Unity and brotherhood is nurtured in the camp with the aim of it lasting the rest of their lives. All circumcised men belong to a circumcision age-set. The pastoralists who live on the plains go through an alternative initiation ritual, sapana, and many agriculturalists do it also in order to be blessed and to be allowed to knit a wedding ring, ptïrïm, on the forearm of their wives. These rituals and all other major rituals they go through reflect the importance of cattle in the life of Pokot men. Their lives revolve around acquiring as many of them as they can and to protect them from sicknesses and enemies. They are the chief form of wealth and ritual sacrifices. In some rituals young men are urged to go raiding to acquire wealth, and successful raiders and those who kill enemies are regarded as heroes. A man, who has many heads of cattle can afford to have many wives and children, who are an important labor force tending to his wealth. Such a man can establish many joined cattle ownerships, tïlya, across clan lines, through which he distributes his wealth and decreases the danger of losing all his animals in a raid or famine. He can become powerful and enjoys respect in his community, which is the most important male value. Apart from acquiring wealth it is important for a man to beget sons to prolong his life as a member of the family as a guardian spirit.; Þessi ritgerð, sem er rannsókn á heimi karlmanna Pókot-þjóðflokksins í Kenýa, er
framlag til karlmennskurannsókna. Reynt er að svara spurningunum: Hvernig móta
þau ritúöl sem menn fara í gegnum á lífsleiðinni frá vöggu til grafar, aldurshópakerfið
og stofnanir karlmanna, stríð og kúaskipti, tïlya, sjálfsmynd þeirra? Hvaða gildum
miðla þau? Hvaða gildi eru sértæk fyrir Pókot-menn? Hvernig tileinka þeir sér þau? Í
upphafi er Pókot-samfélagið sett í víðara afrískt samhengi sem hluti af Nílótum,
hinum stóra hópi þjóðflokka og undirflokknum Kalenjin. Því er haldið fram að þessi
þjóð sé ung í núverandi mynd, ef til vill frá seinni hluta 19. aldar, og að hún hafi orðið
til við blöndun Okiek-frumbyggjaþjóðflokksins Cherangany og nágranna þeirra. Til
að skilja betur ritúöl karlmanna eru þau sett inn í ramma trúarbragða Pókot-fólksins
sem þau eru hluti af og helstu þáttum þeirra lýst. Trúarbrögð Pókot-manna eru borin
saman við afrísk trúarbrögð almennt. Sem ungbörn fara drengir í gegnum ritúalið „að
gróðursetja andann” þar sem forfeðraandi úr fjölskyldunni verður hluti af lífi þeirra.
Drengir eru umskornir og innvígðir í leyndardóma karlmanna og verða þannig
fullveðja karlmenn í samfélaginu. Þeir dvelja í þrjá og hálfan mánuð í
umskurnarbúðum þar sem þeir þurfa að fara í gegnum ýmis stig og ritúöl og þola
mikið harðræði til verða góðir hermenn. Lögð er áhersla á að skapa einingu og
bræðralag í búðunum sem á að vara alla ævi. Allir umskornir karlmenn tilheyra
umskurnar-aldurshópi. Hirðingjarnir sem búa á sléttunum hafa annað innvígsluritúal,
sapana, en akuryrkjumenn fara einnig í gegnum það til að fá blessun og leyfi til að
hnýta giftingarhring, ptïrïm, á framhandlegg eiginkvenna sinna. Þessi og önnur
mikilvæg ritúöl á lífsleiðinni endurspegla mikilvægi nautgripa í lífi Pókotmanna en líf
þeirra snýst um að eignast eins marga og þeir geta og varðveita þá fyrir óvinum og
sjúkdómum. Nautgripir eru æðsta form auðs og fórna. Ungir menn eru hvattir til að
fara í kúaránsferðir í sumum ritúölum til að afla sér auðs og þeim sem verður vel
ágengt í slíkum ferðum eru virtir sem hetjur. Maður sem á margar kýr hefur ráð á að
eignast margar eiginkonur og börn sem eru mikilvægt vinnuafl til að hugsa um eignir
hans. Hann getur komið á mörgum kúaskiptasamböndum, tïlya, við aðra menn þvert á
ættflokkatengsl. Á þann hátt dreifir hann eignum sínum og minnkar hættuna á því að
missa öll dýrin í kúaráni eða óáran. Slíkur maður getur orðið valdamikill og nýtur
virðingar í samfélaginu en það er mikilvægasta gildi karlmanna. Auk nautgripa er
mikilvægt fyrir mann að geta sonu til að framlengja líf sitt í fjölskyldunni og verða
verndarandi afkomenda sinna.
2006-06-01T00:00:00ZThe impact of low-carbon consumption options on carbon footprints in the Nordic region
https://hdl.handle.net/20.500.11815/4770
The impact of low-carbon consumption options on carbon footprints in the Nordic region
Olson, Sarah; Heinonen, Jukka; Ottelin, Juudit; Czepkiewicz, Michał; Árnadóttir, Áróra
Changes in personal consumption play an important role in the reduction of greenhouse gases (GHGs) to stay within the 1.5-degree warming carbon footprint budget. Affluent countries have high carbon footprints from a consumptive perspective and therefore have a high potential to reduce emissions from personal consumption. To study this potential, we look at the consumption-based carbon footprints of respondents from a carbon footprint calculator survey from the Nordic countries to compare the carbon footprints of those who participated in selected low-carbon consumption options to those that did not. The total sample size of the survey is 8,000 households. We analysed seven low-carbon consumption options within the domains of diet, transportation and housing energy. An input-output based hybrid assessment model was used to calculate the consumption-based carbon footprints. In addition to analysing these options separately, we also analysed them in combination. The lowest carbon footprints were associated with those respondents who did not own a car or had a vegan or vegetarian diet, and the largest difference in emissions was associated with not flying and not owning a car. Rebound effects for the consumption options were largely limited and were mostly not significant. Participation rates in the low-carbon consumption options were generally low. These results underscore the need for higher rates of adopting multiple low-carbon consumption options and can inform policy on which consumption options could be the most impactful.
2024-03-04T00:00:00ZTemporal and intra-thallus variation in arsenic species in the brown macroalga Laminaria digitata
https://hdl.handle.net/20.500.11815/4769
Temporal and intra-thallus variation in arsenic species in the brown macroalga Laminaria digitata
Sim, Rebecca; Feldmann, Joerg; Stengel, Dagmar B.; Pétursdóttir, Ásta H.
Environmental context. Arsenic contamination has a disproportionate effect on marine ecosystems. Organisms such as some marine macroalgae, which accumulate potentially toxic elements from the surrounding environment, have developed an internal conversion process that is not yet fully understood. Are arsenic-containing sugars a product of detoxification, or simply the result of phospholipid degradation?
Rationale. Arsenosugars (AsSugar) account for the majority of total arsenic in common seaweed species, yet it is unclear whether these are formed through some detoxification pathway for inorganic arsenic or are precursors/degradation products of arsenic-containing phospholipids in the cell wall.
Methodology. Temporal and intra-thallus variations in water-soluble arsenic were measured by HPLC-ICP-MS, as well as total non-polar and polar arsenic-containing lipids by ICP-MS in Laminaria digitata to offer potential insight into the origins of arsenosugars. Water-soluble speciation with and without freeze-drying were also compared to determine whether freeze-drying changes the water-soluble As speciation.
Results. In general, lower levels of total As were detected in the samples collected in May (39.2–74.5 mg kg−1) compared to those collected in February (72.6–151 mg kg−1). The concentration of arsenate was found to consistently increase along the thallus from the holdfast/stipe (0.78–1.82 mg kg−1) to the decaying fronds (44.4–61.0 mg kg−1) in both months, and AsSug-SO3 was the dominant AsSugar in the majority of samples. The extraction efficiency was lower in fresh samples (64–77%) than in freeze-dried (95–116%) from the same month. Water-soluble, polar AsLipids, and residual As concentrations, were generally highest in February, and the non-polar AsLipids accounted for <0.42% of totAs in all samples.
Discussion. Our results suggest that the arsenosugars are not a product of arsenic detoxification, but a by-product of normal biological activity. It is probable that the arsenosugars are bound to the cell membrane within the Laminaria digitata cells, and lyophilisation is required to release them quantitatively. Future research should focus on speciation of polar lipid-soluble As extracted from fresh samples to determine if the lower extraction efficiency observed in this study is due to the As being in an unextractable form, i.e. lipids, and thus is not removed from cells during water-based extractions.
2023-01-01T00:00:00Z