Zebrafish Health & Husbandry: ILAR Journal 2012 Flashcards Preview

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Flashcards in Zebrafish Health & Husbandry: ILAR Journal 2012 Deck (134)
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1
Q

Which of the following fields of research was the first one to expand when using zebrafish models as part of an integrative approach to improve human health:

     a. Toxicology
     b. Aging
     c. Oncology
     d. Developmental genetics
A

d. Developmental genetics

2
Q

Which of the following agents is the most common cause of Microsporidiosis in laboratory zebrafish:

     a. Pseudoloma neurophilia
     b. Pseudocapillaria tomentosa
     c. Schistocephalus solidus
     d. Pleistophora hyphessobryconis
A

a. Pseudoloma neurophilia

3
Q

Which of the following Mycobacteria has been found to cause severe outbreaks of Mycobacteriosis in laboratory zebrafish:

     a. M. fortuitum
     b. M. chelonae
     c. M. haemophilium
     d. M. ulcerans
A

c. M. haemophilium

4
Q

Which of the following wild-type strains was the one used for the sequencing and mapping of the zebrafish genome:

     a. AB
     b. SAT
     c. TL
     d. SJA
A

b. SAT

5
Q

Name the two most common infections found in zebrafish submitted to the ZIRC diagnostic laboratory

A

Pseudoloma neurophilia (74%)

Mycobacterium spp. (43%)

6
Q

Which species of mycobacteria is of particular concern because it infects humans?

a. M. fortuitum
b. M. haemophilum
c. M. chelonae
d. M. marinum

A

d. M. marinum

7
Q

True or False: Acid fast staining is the primary technique recommended by the Zebrafish International Resource Center for routine surveillance.

A

True

8
Q

True or False: The ability of piscine mycobacteria to persist in surface biofilms is not one of the challenges in eliminating infection.

A

False

Mycobacterium are facultative pathogens that can survive outside the host on biofilms. Screening animals & eggs alone may be ineffective at elimnating the infection.

9
Q

Which of the following is the currently recommended treatment for elimination of mycobacteria from a facility once it has been established?

a. Vaccination with extracellular mycobacterial products
b. Depopulation
c. Vaccination with attenuated mycobacteria
d. Rifampicin

A

b.Depopulation

10
Q

T/F: Mycobacteriosis in fishes is attributable to 3 species of mycobacteria: M. chelonae, M. fortuitum, & M. marinum

A

False: using more refined diagnostic methods, at least 16 mycobacterium species have been in fish

In zebrafish, at least 6 have been described

11
Q

Which of the following are clinical signs of mycobacteriosis in zebrafish?

  1. Non-specific dermal lesions
  2. Raised scales
  3. Swollen abdomen
  4. Emaciation
  5. No clinical signs
  6. Erratic swimming
A

Clinical signs of mycobacteriosis are broad ranging, so any of the listed clinical signs are possible

12
Q

ID male and female zebrafish

A

The male is smaller & more stream-liined

The female is larger with a distented abdomen

13
Q

T/F: Mycobacteria have been observed in the ovaries of zebrafish, suggesting the potential for contamination of off-spring, if not vertical transmission

A

True

14
Q

What is considered to be the primary route of transmission of mycobacteria in fish?

A

Ingestion: the intestine is likely the primary route of invasion

This highlights the importance of removing dead and moribund fish as soon as possible

15
Q

Which of the following species of mycobacterium is of particular concern regarding zoonotic disease.

  1. M. chelonae
  2. M. fortuitum
  3. M. marinum
  4. M. haemophilum
A

M. marinum

It is known to infect humans

Direct transmission from fish has not been confirmed, but is strongly suspected

16
Q

What is thought to limit the establishment and spread of fish-associated mycobacterial infections in humans?

A

Human core body temperature

Fish-associated mycobacteria do not grow well at 37ºC

17
Q

Name two acid fast stains that can be used to ID mycobacteria in histologic sections.

A

Ziehl-Neelsen

Fite’s

18
Q

Describe culture conditions used for mycobacteria

A

Middlebrook 7H10 agar supplemented with oleic acid, albumin, dextrose & catalase

Or growth on Lowenstein-Jensen Slants

Cultures are incubated at 28-30ºC and monitored for 6-8 weeks

19
Q

Which of the following is considered the gold-standard for a thorough investigation and subsequent storage and cataloguing of mycobacterial species and strains?

  1. Acid fast staining of histo sections
  2. PCR detection & sequencing
  3. Culture
A

Culture

PCR detection & sequencing are useful to ID mycobacterial species, but not strains

20
Q

T/F: Different strains of a given species of mycobacterium will develop their own unique properties & challenges.

A

True

21
Q

Which of the following mycobacteria are associated with low-level chronic disease? Which are associated with higher virulence, disseminated infections, & higher levels of mortality?

  1. M. marinum
  2. M. chelonae
  3. M. abscessus
  4. M. fortuitum
  5. M. haemophilum
  6. M. peregrinum
A

M. marinum & M. haemophilum are associated with a higher level of virulence, disseminated infections & higher mortality rates

The others are associated with low-level chronic disease

22
Q

T/F: Environmental conditions & the nutritional and immunological state of zebrafish are probably the most important variables affecting the pathogenesis of mycobacteriosis.

A

True

While different species & strains of mycobacterium have different effects, the overall health of the zebrafish affects the course of disease the most

23
Q

T/F: All lines of zebrafish appear equally susceptible to mycobacterial infection

A

False

Different lines of zebrafish appear to be more or less susceptible to infection based on a cross-sectional study at a single facility (2 references listed)

24
Q

Name the three tissues most likely to harbor mycobacterial granulomas in zebrafish.

A

Liver, kidney, spleen

25
Q

T/F: In the aquatic environment, biofilms are found on all surfaces, and this biofilm and the detritus at the bottom of the tank are thought to be the source of mycobacterial infection.

A

True

26
Q

T/F: The efficacy of the standard practice of bleaching eggs for 10 minutes at 50ppm is well established.

A

False

Various studies have evaluated the efficacy of bleach solutions on mycobacterial cultures exist, but no evidence regarding the efficacy of bleach myocbacteria in biofilms or on eggs exists.

Bacteria harbored within eggs are protected from disinfectants & present a risk to other eggs

27
Q

T/F: The life cycle of Microsporidia consists of two general developmental stages: merogony and sporogony

A

True

Meronts multiply within the infected host cell, eventually forming sporonts and then spores, which are ultimately released from the host cell and transmit the infection.

28
Q

T/F: Microsporidia are generally susceptible to many standard forms of surface decontamination used for fish eggs, such as chlorine and iodophores.

A

False.

The infectious spore stage has a thick, chitinous endospore making it extremely resistant to environmental stress and lysis.

29
Q

T/F: Spores of P. neurophilia relesed from aggregates in myocytes or peripheral nerves in the somatic muscle typically elicit a severe inflammatory reaction.

A

True

30
Q

T/F: Spores of P. hyphessobryconis can also be observed in the kidney, spleen, intestine and ovaries in heavier infections.

A

True

31
Q

T/F: PCR-based assays are recommended for the specific detection of P. hyphessobryconis.

A

False.

No PCR-based assays currently exist for the specific detection of this parasite

32
Q

T/F: the cryopreservation of zebrafish sperm prevents the spread of microsporidians.

A

False.

Microsporidians have the ability to survive during cryopreservation.

33
Q

T/F: Pseudoloma neurophilia is the most common pathogen detected in zebrafish

A

True

Detected in 74% of the facilities examined by the ZIRC diagnostic service in 2010

34
Q

What does ZIRC stand for?

  1. Zebrafish International Research Consortium
  2. Zebrafish Institute Research Center
  3. Zebrafish International Resource Center
  4. Zebrafish International Research Consortium
A

Zebrafish International Resource Center

35
Q

Which of the following are clinical signs of Pseudoloma neurophila infection in zebrafish?

  1. Emaciation
  2. Lordosis
  3. Scoliosis
  4. No clinical signs
  5. Reduced fecundity
A

Infection produces a wide range of clinical signs & any of the listed signs are possible

36
Q

Which of the following is a muscle-infecting microsporidium that has been described in laboratory populations of zebrafish?

  1. Paracheirodon innesi
  2. Pleistophora hyphessobryconis
  3. Danio nigrofasciatus
  4. Encephalitozoon cuniculi
A

Pleistophora hyphessobryconis

37
Q

The following histology was obtained from a fish with emaciation and scoliosis…what is the diagnosis?

A

Pseudoloma neurophilia - microsporidiosis

A. Low magnification showing inflammation in skeletal muscle. Bar = 100 µm. Inset at upper left shows macrophage with 4 spores

B-D. Spores (arrows) in eggs. B) H&E. C) Acid fast, spores fill a degenerate egg, D) Gram, showing blue-staining spores.

E. Spores in spinal cord stain blue with the tissue Gram stain.

38
Q

T/F: Microsporidian spores can often be seen in wet mounts from infected tissues and are discernible by their generally refractile appearance and characteristic posterior vacuole.

A

True

39
Q

This is a wet-mount and geimsa stained tissue prepared from the brain & spinal cord of a zebrafish at necropsy. What is the diagnosis?

A

Microsporidiosis - Pseudoloma neurophilia

Pseudoloma from brain.

A. Giemsa stain

B. Wet mount with Nomarski’s phase interference

Bar = 10 µm.

40
Q

What additional stain requiring fluorescence microscopy can be used to increase sensitivity of microsporidian spore detection by histology. An image below represents this stain.

A

Chitin-specific Fungi-Fluor stain

A. Low magnification showing numerous spores (stained blue with DAPI filter) in spinal cord xenomas (arrow).

B. High magnification of spores (S) in ovaries.

41
Q

In which of the following tissues may large aggregates of P. neurophilia spores be seen?

  1. Neural tissue of the posterior brain & spinal cord
  2. Kidney
  3. Skeletal muscle
  4. Gut epithelium
  5. Ovary
A

Large aggregates are typically found in neural tissue of the posterior brain & spnal cord

Smaller groups or individual spores can be seen in the other tissues listed

42
Q

What molecular diagnostic techiques are available for detecting P. neurophilia?

A

Convential & real-time PCR targeting the small subunit of the ribosomal DNA gene are available

43
Q

T/F: Microsporidia are spread through direct transmission through ingestion of spores and infected tissue in the water

A

True

44
Q

T/F: Zebrafish frequently spawn spontaneously in aquaria, and hence release of eggs, ovarian fluids, and tissues at spawning provides an important potential route of horizontal transmission.

A

True

45
Q

T/F: Maternal transmission has not been reported for microsporidans in fish

A

False

Vertical transmission of microsporidans have been documented in fish

Experimental & observational lines of evidence suggest that maternal transmission of P. neurophilia, either transovarial or transova, does occur

46
Q

Which of the following is considered the best method for routine health monitoring of zebrafish?

  1. Serologic testing
  2. PCR
  3. Culture
  4. Histopath
A

Histopathologic analysis is the best overall method for routine health monitoring of zebrafish because of the ability to assess all tissues and to detect novel pathogens, which would not be detected by PCR. Serologic testing is not available for zebrafish.

47
Q

T/F: Exposing a population of known uninfected fish to the untreated effluent from other tanks on the system allows facility managers to assess the infection status of fish in the system on a large scale

A

True

Also…exposing sentinels to treated effluent can be used to assess the decontamination efficacy of the system.

48
Q

What is the recommended quarantine procedure for introducing new fish into a facility?

A

Bring adults into quarantine, spawn them, and then move only the progeny of those adults that are screened and determined to be microsporidian-free into the main facility.

49
Q

Which of the following doses of UV sterilization has been shown to be effective in the inactivation of microsporidian parasites of human concern?

  1. 1 mJ/cm sq
  2. 6 mJ/cm sq
  3. 30 mJ/cm sq
  4. 100 mJ/cm sq
A

6 mJ/cm sq

50
Q

What is the generally recommended method of disinfecting zebrafish eggs with bleach?

Is this effective at killing P. neurophilia?

A

Bath treatment with 25-50 ppm bleach for 10 minutes

No, it is not effective at killing P. neurophilia & probably not mycobacterium

51
Q

T/F: Microsporidian spores are highly resistant to current methods of surface sterilization of eggs, and these methods cannot be relied upon to eliminate P. neurophilia or other microsporidia from a population

A

True

52
Q

T/F: Current molecular diagnostic methods can easily be applied to the testing of eggs, sperm, and larval fish. These methods have been used to establish P. neurophilia SPF colonies of zebrafish

A

True

53
Q

What level of chlorine is required to kill >95% of P. neurophilia spores?

  1. 5 ppm, pH 7
  2. 5 ppm, pH 8
  3. 100 ppm, pH 7
  4. 100 ppm, pH 8
A

100 ppm, pH 8

Efficacy of chlorine is pH dependent

This dose is lethal for embryos

54
Q

T/F: There are currently no known treatments for microsporidosis in zebrafish

A

True

Elimination by rederivation from uninfected adults is likely necessary for P. neurophilia

55
Q

List some reasons why zebrafish have emerged as leading model for mechanistic cancer research.

A

Sophisticated genetic and genomic resources

Tractability for tissue-specific transgene expression

Cost effectiveness for enhancer and suppressor screens once a cancer model is established

56
Q

T/F: Unlike other species, dietary and husbandry practices do not have a significant impact on the incidence of tumor development in zebrafish

A

False - diet and husbandry do affect the incidence and histologic spectrum of neoplasia in zebrafish

57
Q

T/F: When compared to zebrafish raised in flow-through systems, zebrafish fed commercial diets containing fish meal and reared in certain recirculating water systems showed far higher tumor incidences and a much wider variety of histological types of neoplasia.

A

True

Recirculating systems & fish-meal diets are associated with a signifcantly higher incidence of neoplasia

58
Q

What is the most commonly found mycobacterial species of fish?

A

M. chelonae

59
Q

Where are Myxidium species found in infected fish?

A

Mesonephric ducts - invariably confined to the lumen or attached to the surface of epithelial cells & not associated with significant histopathologic changes

60
Q

Name the capillarid nematode that is found in the proximal intestinal tract of zebrafish

A

Pseudocapillaria tomentosa

61
Q

T/F: Fish affected with Pseudocapillaria are often clinically symptomatic & emaciated due to profound wasting.

A

True

62
Q

This is a gut section from a zebrafish with severe wasting. What is the diagnosis?

A

Pseudocapillaria tomentosa

Histological sections of zebrafish with Pseudocapillaria tomentosa infections. Diffuse, severe chronic inflammation, extending from lamina propria (LP) into to visceral cavity.

Pa = inflammation in pancreas.

Arrow = nematode. Hematoxylin and eosin.

Bar = 100 µm

63
Q

Name the condition in zebrafish that may be caused by egg retention in fish that have not had the opportunity to spawn frequently

A

Egg-Associated Inflammation & Fibroplasia (EAIF)

The condition is often subclinical, but affected females may have a swollen abdomen

64
Q

How might EAIF confound toxicology studies?

A

Interpretation of endocrine disrupting compound studies might be confounded by spontaneous occurrence of chronic oophoritis, the hallmark of EAIF

65
Q

What is the significance of hepatic megalocytosis in zebrafish?

A

Megalocytosis is characterized by hepatocytes that have both enlarged nuclei and excessive amounts of cytoplasm.

Hepatic megalocytosis can be caused by both natural toxins (cyanobacteria, alkaloids from plants) or a variety of anthropogeneic agents (recirculating systems with fluidized sand sanitizers, carcinogens)

66
Q

T/F: Bile duct proliferation in the liver is often noted in normal appearing fish and seems to be particularly common in some lines of TL zebrafish.

A

True

Can confound studies looking at hepatic carcinogens b/c the appearance may be similar to neoplasia

67
Q

Which of the following two neoplasms are commonly observed in histological examinations of apparently healthy sentinel fish?

  1. Hemangiosarcoma
  2. Ultimobrachial gland tumors
  3. Spindle cell sarcomas
  4. Intestinal carcinoma
A

Ultimobrachial gland tumors & Intestinal carcinoma

The others are not reported in zebrafish

Other spontaneous tumors in zebrafish include:

seminomas

malignant peripheral nerve sheath tumors

hepatocellular carcinomas

68
Q

T/F: Zebrafish are not capable of contracting viral infections

A

False.

Zebrafish have been repeatedly infected experimentally with a variety of viruses.

69
Q

What viral family is infectious spleen and kidney necrosis virus found in? Is this a DNA or RNA virus?

  1. Herpesviridae
  2. Paramyxoviridae
  3. Iridoviridae
  4. Reoviridae
  5. Birnaviridae
A

Iridoviridae

DNA

70
Q

What is the genus and species of the Atlantic salmon?

A

Salmo salar

71
Q

How many immunoglobulin classes does the zebrafish exhibit?

A

Three: IgD, IgM, and IgZ

72
Q

T/F: The zebrafish genome is devoid of retroviral elements and transposons.

A

False

The zebrafish genome contains multiple endogenous retroviruses, retrotransposons, and other retroid agents.

73
Q

What do we care if zebrafish have underlying viral infections?

A
  • Regardless of whether clinical signs are evident, underlying infection with an unknown viral agent may confound experimental infection studies with a different pathogen.
  • Viral infections may confound toxicologic studies or other studies that rely on histopathology by introducing unexplained histopathologic changes.
  • Underlying infections may alter immune function
  • Increased inflammation and altered cytokine production caused by underlying infections can affect cell proliferation rates, creating a confounding variable in tumorigenesis models.
  • Zebrafish may be hosts to unknown oncogenic viruses, which may be a confounding variable in cancer research.
74
Q

Why is biosecurity important for laboratory zebrafish?

A

Ornamental zebrafish are often raised together with other species that harbor numerous pathogens. A recent example of pathogen transmission from the pet trade to laboratory zebrafish is neon tetra disease, caused by the microsporidian Pleistrophora hyphessobryconis.

75
Q

T/F: Zebrafish exhibit both the innate and adaptive arms of the immune system

A

True

76
Q

With respect to the zebrafish immune system, which of the following is false?

  1. Leukocyte populations including B & T lymphocytes, monocytes, & phagocytic tissue macrophages
  2. Inflammatory mediators & signaling molecules
  3. Both Rag1 & Rag2 genes have been identified
  4. Both T-cell receptor genes & B-cell immunoglobulin genes exhibit V(D)J recombination
  5. 24 putative toll-like receptor variants have been identified in zebrafish
A

None - all of these describe the zebrafish immune system

77
Q

Define “nutrition”

A

process by which living organisms acquire and assimilate nutrients for survival, growth, reproduction, and replacement of tissues.

78
Q

What are two major limitations in the field of zebrafish nutrition?

A

A standard diet has not been established

The daily dietary nutrient requirements for any life stages are unknown.

79
Q

Zebrafishes are:

a) eurythermal or b) sternothermic

Prefer a) areas of hydrodynamic activity or b) still water

Tolerate a) low ionic content or b) high ionic content

A

a) eurythermal: able to tolerate a wide range of temps (6-38℃)
b) still water
a) low ionic content (but not RO or distilled water)

80
Q

What are the three general life support systems used to support zebrafish?

A
  1. Static renewal system
  2. Recirculating system
  3. Flow-through system
81
Q

T/F: The mechanism of sex determination in zebrafish is not known

A

True

Zebrafish have no apparent heteromorphic (sex) chromosomes

82
Q

T/F: It has been observed that sex ratios in propagated colonies are often variable, depending on rearing density, hypoxia, or food availability

A

True

Environmental factors, in addition to genetics, play a role in sex determination

83
Q

T/F: In zebrafish, gonad development for both females and males is preceeded by a juvenile ovary stage

A

True

The juvenile ovary undergoes apoptosis and is restructured into a testis in males

84
Q

T/F: Zebrafish are oviparous organisms with external fertilization and no parent care

A

True

85
Q

Olfactory cues or pheromones have been show to play a role in which of the following?

  1. Synchronize mating behavior
  2. Increased egg production in females exposed to male pheromones
  3. Inhibition of spawning in females
  4. Mediate kin recognition
A

All are correct

86
Q

T/F: As schooling fish, zebrafish do not form social hierarchies with dominant and subordinant individuals

A

False

Zebrafish do form social hierarchies which are important in breeding

87
Q

Describe the three general phases of zebrafish courtship behavior.

A
  1. Initiatory stage: males follow or swim alongside females and exhibit abrupt swimming movements
  2. Receptive/Appetive stage: males touch the female’s side or tail with their noses or heads; females may remain still during this courtship
  3. Spawning stage: male and female swim side by side in the same direction and position their genital pores close to one another; male performs rapid tail oscillations against the female’s side, triggering oviposition and release of sperm
88
Q

At what age to laboratory zebrafish attain sexual maturity?

A

3 months

89
Q

T/F: Zebrafish mating is initiated by the onset light and spawning typically takes place over a short period thereafter

A

True

90
Q

T/F: Because zebrafish are group spawners, group crosses/matings are used exclusively in the laboratory. Single-pair matings simply do not result in viable off-spring.

A

False

both single-pair matings and group crosses are used in the laboratory

91
Q

What is the purpose of the perforations in the bottom of this tank?

A

Allows the fertilized eggs protection after spawning…the eggs pass throught he perforations protecting them from predation

92
Q

What are some potential uses of single-pair matings in zebrafish?

A

ID carriers of recessive mutations

ID carriers of dominant traits visualized only during development - carriers must be ID by examining the progeny

93
Q

TU, AB, WIK, and Tupfel ling fin are examples of what type of zebrafish line?

  1. Inbred
  2. Transgenic
  3. Wild-type
  4. Knock-out
A

Wild-type

94
Q

What type of line is TAB?

A

Hybrid line between TU and AB

95
Q

T/F: There are currently no zebrafish inbred lines in which all individuals are identical and homozygous

A

True

Inbreeding significantly reduces fertility and survivability in zebrafish

96
Q

Describe 2 different types of tank designs for mating cross setups?

A

Mating crosses can be set up:

  1. In a static water tank over marbles
  2. In a container with a perforated bottom holding the fish. This container is located inside another container thereby protecting the eggs.
97
Q

At what day post fertilization is the yolk completely absorbed which leaves the zebrafish larvae dependent on exogenous feeding?

a. 3
b. 7
c. 10
d. 15

A

b. 7

98
Q

What is the preferred pH range of housing water for zebrafish?

a. 6.4-6.8
b. 6.8-7.2
c. 7.2-7.6
d. None of the above

A

b. 6.8-7.2

99
Q

What is the standard rearing temperature for zebrafish?

What effect does temperature have on development?

A

28.5℃

Lower rearing temperature slows development while higher temperature accelerates it.

100
Q

T/F: Feeding zebrafish Paramecium alone during the early larval stages can result in smaller larvae and lower survival rates, suggesting that Paramecium alone may be insufficient for nutrition

A

True

Paramecium-only diets are not adequate for proper growth and good survival rates. Although brine shrimp (Artemia) are not natural food items for zebrafish, they appear to fulfill needs for proper development.

101
Q

At what age do zebrafish show decreased fertility, fecundity, and health.

A

Zebrafish older than 18 months show decreased fertility, fecundity, and health.

102
Q

Which of the items listed below is not a common type of filtration in aquatic systems:

a. Biological Filtration
b. Chemical Filtration
c. Mechanical Filtration
d. Parasitic Filtration

A

d. Parasitic Filtration

103
Q

T/F: The key advantage to UV sterilization is that there is very little maintenance needed once the system is established.

A

False

UV sterilizers need regular maintenance to perform adequately.

104
Q

T/F: Most supplies of water from municipal sources contain chemicals toxic to fishes and must be pre-treated before addition to the system.

A

True

Most water supplies contain chlorine, chloramines, and possible leached heavy metals.

105
Q

T/F: It is critical to keep all bacteria to a minimum in recirculating aquatic systems and regular addition of antibiotics is helpful.

A

False

Recirculating systems are critically dependent on bacteria in the biofilter to breakdown nitrogenous wastes.

106
Q

Which modality of water quality testing and monitoring is preferred?

a. Automated monitoring
b. Manual monitoring
c. A combination of automated and manual testing

A

c. A combination of automated and manual testing

107
Q

Name important factors with regard to water quality for the maintenance of zebrafish.

A

Temperature

pH

Salinity

Alkalinity

Hardness

Dissolved Oxygen

Nitrogenous Wastes

108
Q

What is the target range for total ammonia nitrogen (mg/L) in zebrafish water?

  1. Zero
  2. 10
  3. 100
  4. Up to 200
A

Zero

109
Q

What is the target range for nitrite (mg/L) in zebrafish water?

  1. Zero
  2. 10
  3. 100
  4. Up to 200
A

Zero

110
Q

What is the target range for nitrate (mg/L) in zebrafish water?

  1. Zero
  2. 10
  3. 100
  4. Up to 200
A

Up to 200

111
Q

Describe how reverse osmosis water filters work

A
  1. RO water filters are actually several individual water filters placed in series - each filter is referred to as a “stage”
  2. 1st stage removes sediment - particulate filter
  3. 2nd stage removes chlorine - activated carbon filter
  4. The water is then pushed through the RO membrane against its natural osmotic flow
  5. The water can then be de-ionized if needed
112
Q

T/F: RO/deionized water must be conditioned with sea salts before being delivered to a life support system

A

True

This adds critical minerals

113
Q

Describe how a flow-though life support system works

  1. What is the general water flow?
  2. What is the direction of water flow?
  3. Continuous or periodic?
  4. Water source consideration…..
A
  1. Clean water is pumped into tanks, fish excrete wastes, and the effluent is flushed out
  2. Flow is unidirectional - clean water in, effluent water out
  3. May be continuous or periodic
  4. Requires a large source of conditioned water
114
Q

Describe how a recirculating life support system works.

  1. Describe the basic water flow
  2. How are wastes removed?
  3. Comment on water consumption
A
  1. Clean water is pumped into tanks, fish excrete wastes, effluent is pumped into “treatment zone” where wastes are removed before water is returned to the system
  2. Water recirculates in the system after filtration to remove wastes
  3. Greatly REDUCES water consumption
115
Q

Why is it critical that solid wastes be removed from a life support system?

A

Solid wastes are produced by the accumulation of uneaten food and fish feces and have a detrimental effect on the efficiency of biological filtration

  1. Reduces available oxygen for biological filter
  2. Increases production of ammonia nitrogen
  3. Favors growth of heterotrophic bacteria that compete with bacteria of biological filter
116
Q

Which is the function of Nitrosomas spp. in the biological filter?

A

Oxidize ammonia in the water to nitrite

117
Q

Which is the function of Nitrobacter & Nitrospira spp. in the biological filter?

A

Oxidize nitrites to nitrates

118
Q

What are the three factors all biological filters must maximize to function appropriately?

A
  1. Surface area of the media
  2. Water contact
  3. Oxygenation
119
Q

Trickling media, moving bed bioreactors, and fluidized bed are all types of what kind of filter?

  1. Solids filter
  2. Biological filter
  3. Chemical filter
A

Biological filters

120
Q

What is the function of chemical filtration in a zebrafish life support system?

Give some examples of chemical filters…

A

Removal of organic compounds, such as ammonia, not removed in solid and biological filtration that contribute to color and odors in effluent water. Will also remove chlorine which can come from municipal water supplies.

Activated carbon filter, ion exchange resins, ammonia binders

121
Q

What is the recommended level of dissolved oxygen (mg/L) in aquaculture systems?

  1. 1
  2. 2
  3. 3
  4. >4
A

>4 or as close to saturation as possible

122
Q

What is the recommended level of dissolved carbon dioxide (mg/L) in aquaculture systems?

  1. <20
  2. 20-40
  3. 40-60
  4. >60
A

<20 mg/L

123
Q

What is the most frequently applied water disinfection method in zebrafish housing systems?

A

Ultraviolet disinfection

124
Q

Name an advantage of using UV disinfection in aquaculture systems.

A

Relatively safe to operate

Not harmful to the cultured species

125
Q

Why must bases be added to the water of life support systems?

A

Nitrifying bacteria of the biofilter continually produce acids, which if left unbuffered would eventually acidify the water to the point where nitrification would not occur. This can lead to ammonia spikes that can stress, injure or kill the fish

126
Q

What is the purpose of a fluidized argonite reactor in a life support system?

A

It is an alternative to the standard sodium bicarbonate dosing method of maintaining pH

Aragonite is a form of calcium carbonate that, when in contact with water with pH <8, dissolves into calcium (adds to hardness of water) and carbonate (helps maintain pH)

127
Q

T/F: Low levels of dissolved oxygen are responsible for more mortalities than any other parameter in aquaculture.

A

True - although this is rarely a limiting factor in zebrafish systems.

128
Q

Leaching of what compound from older polycarbonate and polysulfone tanks can lead to serious reproductive problems in vertebrates, including fish?

A

Bisphenol-A (BPA): an estrogen mimic

129
Q

What is an considered an acceptable stocking density for adult zebrafish?

  1. 1-5/L
  2. 5-10/L
  3. 10-15/L
  4. 15-20/L
A

5-10/L

130
Q

The stress response in fish can be generally categorized into how many physiological stages? Name the stages.

A

Three – primary, secondary, and tertiary

131
Q

What is the only anesthetic approved for some aquatic species by the US Food and Drug Administration?

A

MS-222 (tricaine methanesulfonate)

132
Q

True or False: Under normal conditions, zebrafish are obligatory gill breathers.

A

True

133
Q

How many levels of anesthesia are there in zebrafish?

A

Six (6) – levels 1-5 and stage 6

134
Q

What organ is the most common target organ for nearly all carcinogens studied in WT & mutant lines of zebrafish?

A

Liver

Compared to mammals, zebrafish and trout more often show mixed hepatic neoplasms with biliary and hepatic components