APS136 Papers Flashcards
The largest free-living animal to inhabit Antarctica all year-round is…
a flightless midge, Belgica antarctica
Larval midges survive the lengthy austral winter…
encased in ice - when the ice melts in summer the larvae complete their 2-year cycle
Larvae constitutively upregulate their … … …, which are… and maintain a high inherent tolerance to temperature stress
heat shock proteins,
- small hsp
- hsp70
- hsp90
In larvae, high or low temperature exposure does not further … these genes nor does it further enhance …
upregulate, thermotolerance
This “preemptive” synthesis of hsps is sufficient to prevent irreversible … … in response to a variety of common … …
protein aggregation, environmental stresses.
Conversely, adults exhibit no … upregulation of their hsps and have a … intrinsic tolerance to high temperatures, but their hsps can be … activated, resulting in enhanced …
constitutive, lower, thermally, thermotolerance
The midge feeds on…
dead plant material, algae and microorganisms
The midge can overwinter in any of the four…
larval instars
The larvae can tolerate freezing…
year round
Wingless adults, which are not …, emerge, mate in …, and lay eggs for a brief period of about … weeks during the summer.
freeze-tolerant, aggregations, 1-2
Summer air temperatures seldom exceed …, but temperatures in the rocks, vegetation and substrate in which the midges live may be … higher
5C, 20C
This study examines the … temperature responses of larvae and adults of the midge, B. antarctica, collected in antarctica during January, when the insect is exposed to the temperature extremes of the … …
high, austral summer
Larvae are frequently subjected to a variety of environmental stressors, including…
- freezing
- dessication
- osmotic stress
- anoxia
When transferred from 4C to 20C 1-2 days after field collection, adults were considerably…
less heat-tolerant than larvae, surviving <1 day at 20C and for even shorter periods at higher temperatures
The 2h conditioning of the larvae at 15,20 or 25C caused … and … survival at 30C.
thermosensitivity, reduced
Likewise, a 2h exposure to 20C failed to protect larvae from a 1d exposure to …
25C
In adults, 1h at 20C … … enhance survival at 30C, but 1h at 25C significantly … survival at 30C
did not, increased
- adults are capable of generating thermoprotection
All 3 hsp transcripts (smhsp, hsp70, hsp90) were expressed at … … in larvae maintained at 4C, whereas adults held at 4C exhibited … or … hsp expression.
high levels,
little, no
Neither high or low temperature exposure further … transcript abundance in the larvae, immediately after the stress nor after return to ambient temperature
increased
In adults, despite little or no hsp expression at 4C, all 3 genes were responsive to … …, suggesting … of the genes.
heat stress, upregulation
Exposure to a variety of environmental stresses that may result in cell injury and protein denaturation did not increase protein … in larvae
aggregation
hsp70 is also expressed constitutively in 2 antarctic marine organisms, a … and a …, and a terrestrial … found in penguin shit constitutively expresses both hsp70 and hsp90.
fish, ciliate, yeast
The chemical cues released by eggs are known to act at the … level (e.g. facilitating species recognition), but recent studies have suggested that they could have roles at the … level by moderating sperm …
interspecific, intraspecific, competition
They used fluorescently labeled … dye in mussels to track the real-time success of sperm as they compete to fertilize eggs, and provide the first direct evidence in any species that competitive fertilisation success is moderated by … … …
mitochondrial, differential sperm chemotaxis
The data is consistent with the idea that egg chemoattractants selectively attract ejaculates from … … males, based on relationships inferred from both … and … genetic markers.
genetically compatible, nuclear, mitochondrial
… … was the ancestral mode of sexual reproduction
broadcast spawning
Sexual selection almost certainly began…
in the sea - with externally fertilising organisms
Eggs of broadcast spawners can moderate the … and … of sperm at the gamete surface, or select sperm … when multiple sperm penetrate the egg
recognition, fusion, nuclei
Eggs can also influence sperm … (prior to the release of gametes) through the release of … …
remotely, chemical attractants
In mussels, it has previously been revealed that chemoattractants have differential effects on the swimming behaviour and physiology of sperm from different conspecific males:
swimming behaviour:
- chemotactic responses
- swimming trajectory
- swimming speed
physiology:
- acrosome reaction
In M. galloprovincialis and many other bivalves, embryos inherit both paternal and maternal mitochondria through a process termed … … …
doubly uniparental inheritance (DUI)
In DUI, maternal mitochondria are inherited in the … tissue of all offspring, while the paternal mitochondria are ultimately transmitted to the … … of male offspring. Initially, however, sperm mitochondria are transferred to all … …
somatic, germ line, fertilised eggs
Mussels were collected from…
Woodman point, cockburn, western australia
- during the spawning season (June-September)
Spawning was induced using a temperature increase from…
ambient to 28C
SR =
standard rival
There were two sources of significant variation in focal male competitive fertilisation success:
a) the male effect
b) the male-by-female interaction
the success of each focal male within a block depended on the specific identity of the focal female chemoattractant
The nuclear data indicated a … population
well-mixed
despite evidence of two historical phylogenetic lineages - northern and southern hemisphere lineages
Competitive fertilisation success was higher when focal male and focal female nuclear genotypes were…
less related, but also when focal males and focal females had the same mitochondrial lineage
The findings suggest that egg chemoattractants allow females to promote fertilisation by more…
compatible males when multiple ejaculates compete
