Management of X. laevis Flashcards
What family does the African clawed frog belong to? How many species are there?
Family Pipidae, 18 species.
Where are research Xenopus exported from?
Cape, South Africa
What environment does Xenopus prefer? What niche does it fill?
Still, opaque, vegetation-filled water. In lakes devoid of fish, Xenopus has evolved to fill the fish niche.
What temperatures are Xenopus acclimated to? What occurs with temperature stress? How do Xenopus cope with temp extremes?
Tolerates wide temp range. Adults stressed at prolonged temps less than 14C (57C) and greater then 26C (81F). Decrease in oocyte quality observed. If temps are too hot (30C, 86F), will evacuate pits in cool mud. In drought, estivates.
What pH and salinity can Xenopus handle in the wild?
Will breed in acidic and alkaline water, but tadpole survival drops in water with a pH <5. Will tolerate elevated salinity (40% seawater) for short time.
What is unique about the fifth toe of Xenopus?
Much longer than the tibia.
How do female and male Xenopus compare?
Females larger. Have a large cloacal papillae. Males develop dark inner surface of their forearms (nuptial pads).
What do the skin secretions of Xenopus include?
Thyrotropin releasing hormone, caerulein, and xenopsin. Magainins - antimicrobial compounds.
How does Xenopus feed?
Lacks a tongue. Lowers buccopharyngeal pressure and opens mouth, suctioning prey in. Shreds prey with hind claws and uses front feet so sweep food into mouth.
Describe Xenopus eyes.
Dorsally-located, lidless, and adapted for vision in air, not water.
Describe scent detection in Xenopus.
Two olfactory cavities - One for scent in water, other for airborne odors.
Describe the lateral line in Xenopus.
Located dorsally and ventrally, retained in adult animals.
What is the vocal apparatus of Xenopus designed for? How do animals vocalize.
Underwater sound production. Vocalize by clicking.
Describe the social structure of Xenopus.
Territorial, form dominant/subordinate hierarchies.
Describe respiration in Xenopus.
Large lungs and heart. Must come to water’s surface to gulp air, as cutaneous resp is not well developed. Tadpoles develop and utilize lungs as well as gills for breathing.
How does Xenopus adapt physiologically during drought?
Produce urea instead of ammonia. When water available, reverts to production of more toxic ammonia, which rapidly dissipates in water.
What is the life span of Xenopus?
Greater than 10 years in wild, 20 years in captivity.
How can cannibalism and bite wounds be decreased in group housed Xenopus?
Provision of hide structures.
When should static systems be changed?
After animals have been fed. Do not disturb frogs for at least an hour, or they may regurgitate
How deep should water be in Xenopus enclosures?
5-20cm. Up to 30-50cm for some authors. Water that is too shallow will increase stress and escape response.
Generally, at what density are Xenopus housed?
1 frog/3L to 4 frogs/5-10L (1L/frog to 2.25 L/frog)
What temperature are most Xenopus housed at?
21-22C
What light cycle are Xenopus housed at? What should be avoided?
12h light-12h dark cycle. Avoid housing directly under very bright light.
What is Xenopus primary means of locating food? What can occur in group feeding?
Olfaction instead of vision, so they will scavenge carcasses. Aggressive during feeding, resulting in bite wounds.
What are common commercial diets for Xenopus? What volume of frog brittle is recommended?
Salmon chow, trout chow, or frog brittle. 1g frog brittle/frog.
What is a disadvantage of feeding excessive chitin-containing animals (crickets, mealworms)?
Intestinal obstruction
Under ideal conditions, when do Xenopus undergo metamorphosis and reach sexual maturity? What can affect this?
2 months and 8 months within hatching. Cool temps will slow development.
In the wild, what does the breeding season correspond to?
Onset of rainy season and prey abundance.
When do females reach optimum egg production?
2-3 years, and continue producing for several years.
How can egg laying be induced in females? How long should ovulated females be rested?
Primed with HCG. Rest for a minimum of 1-3 months.
What do Xenopus eggs possess that reduces the risk of clumping? When do larvae hatch?
Jelly capsule. Hatch 3 days after spawning.
Describe respiration in Xenopus tadpoles.
Have functional lungs and gills, will periodically surface breathe.
How do Xenopus tadpoles feed?
Orient themselves parallel to one another and hover in a head-down fashion, using undulating tails to direct food particles to their mouths. Efficient filter feeders
When do Xenopus tadpoles start feeding?
From hatching through Day 4 they absorb their yolk sac. Begin feeding day 5.
In the wild, what do Xenopus tadpoles eat?
Plankton.
How often are Xenopus tadpoles fed in captivity?
Twice weekly.
At what stocking density are Xenopus tadpoles maintained at?
50/L initially, decreasing to 5/L at onset of metamorphosis.
Approximately how long should oocyte harvest take in Xenopus?
30 minutes or less
What is a concern during anesthetic induction and recovery?
Drowning
What surgical prep is used on Xenopus skin? Why?
Sterile saline. Xenopus skin contains antimicrobial agents. Alternatively can use dilute benzalkonium chloride or chlorhexidine solutions sparingly. No soaps and scrubs.
Describe the oocyte harvest process.
Incision made paramedian in lower abdominal quadrant on either side. Sides can be alternated with sequential surgeries to maximize healing time. Desired number of oocytes excised, remainder replaced. Monofilament nylon the least reactive, silk and chromic gut cause strong reaction and gut dehisces.
What analgesics are used in Xenopus?
Buprenorphine, butorphanol, and meloxicam.
When should sutures be removed following oocyte harvest?
6 weeks, if they have not already sloughed out with shed skin.
