Practical Approaches for Studying Sea Turtle Health and Disease
407
each species. Serologic tests that detect antibody responses to particular
antigens require species-specific reagents. Furthermore, interpretation of
many available biomedical assays relies upon mammalian pathophysiology. We cannot be as certain in reptiles or in each species of sea turtle
that these tests have the same biological and clinical relevance. There is
a tremendous need for basic biomedical research to improve turtle-specific
testing. Sustained investment is required to encourage the development
and improvement of assays for sea turtles and maintain their availability
for comparative studies.
5. Are the investigational materials (biologic samples, carcasses, etc.) of
adequate quality to yield useful results? One must evaluate the cost of
analysis versus the information to be gained when dealing with poorquality or inappropriately handled specimens. Many diagnostic assays and
tests are sensitive to the conditions under which the sample was preserved,
handled, and processed, and may yield spurious results. For example,
plasma that obviously contains hemolyzed red cells will not be very useful
for many biochemical and hematological analyses because the out-of-range
values will reflect hemolysis rather than any disease process (Meyer et al.
1992). Carcasses that are autolyzed (rotting) may be necropsied and tissues
examined grossly, but histological evaluation may not be informative
enough to justify the cost. Similarly, submission of samples for microbial
culture would likely provide spurious results. Plasma and tissue samples
that are collected for certain biochemical assays such as enzyme activity
(e.g., cholinesterase) must be frozen or analyzed quickly, or activity levels
will change. Similarly, samples for RNA analysis must be immediately
frozen at ultracold temperatures or otherwise protected against degradation
with specialized preservatives. Turtles that were dead when found are poor
sources of RNA. Tissues that have been frozen are difficult to evaluate
histologically, and whole blood that has been frozen prior to separation
will have no intact blood cells and will yield a hemolyzed plasma sample.
Tissue specimens that have been frozen at –20∞C will be less likely to
produce successful virus isolation than samples stored at 5 or –70∞C.
Other miscellaneous practical issues must be taken into consideration as well.
These include permits, preparedness, and long-term maintenance of sample archives,
records, and data management. In the U.S., state and federal permits are required
to capture, handle, or sample any sea turtle species (which are protected), and to
possess sea turtle tissues or parts. Any activity that results in a “take,” the death or
removal from the free-ranging population, also requires special permits. This
includes euthanasia of moribund and catastrophically injured animals, which could
provide valuable tissues. In many instances, the best material for analysis is obtained
from a freshly euthanized sick animal. Therefore, even though an interesting disease
case may be found, it would be illegal to collect blood or a skin lesion biopsy unless
specifically permitted to do so. Thus, permit issues should be settled before undertaking health studies. In addition, supplies and materials needed to support health
studies and sample collection must be kept in stock and in date for use when required.
1123 book.book Page 407 Monday, November 11, 2002 11:11 AM
407
each species. Serologic tests that detect antibody responses to particular
antigens require species-specific reagents. Furthermore, interpretation of
many available biomedical assays relies upon mammalian pathophysiology. We cannot be as certain in reptiles or in each species of sea turtle
that these tests have the same biological and clinical relevance. There is
a tremendous need for basic biomedical research to improve turtle-specific
testing. Sustained investment is required to encourage the development
and improvement of assays for sea turtles and maintain their availability
for comparative studies.
5. Are the investigational materials (biologic samples, carcasses, etc.) of
adequate quality to yield useful results? One must evaluate the cost of
analysis versus the information to be gained when dealing with poorquality or inappropriately handled specimens. Many diagnostic assays and
tests are sensitive to the conditions under which the sample was preserved,
handled, and processed, and may yield spurious results. For example,
plasma that obviously contains hemolyzed red cells will not be very useful
for many biochemical and hematological analyses because the out-of-range
values will reflect hemolysis rather than any disease process (Meyer et al.
1992). Carcasses that are autolyzed (rotting) may be necropsied and tissues
examined grossly, but histological evaluation may not be informative
enough to justify the cost. Similarly, submission of samples for microbial
culture would likely provide spurious results. Plasma and tissue samples
that are collected for certain biochemical assays such as enzyme activity
(e.g., cholinesterase) must be frozen or analyzed quickly, or activity levels
will change. Similarly, samples for RNA analysis must be immediately
frozen at ultracold temperatures or otherwise protected against degradation
with specialized preservatives. Turtles that were dead when found are poor
sources of RNA. Tissues that have been frozen are difficult to evaluate
histologically, and whole blood that has been frozen prior to separation
will have no intact blood cells and will yield a hemolyzed plasma sample.
Tissue specimens that have been frozen at –20∞C will be less likely to
produce successful virus isolation than samples stored at 5 or –70∞C.
Other miscellaneous practical issues must be taken into consideration as well.
These include permits, preparedness, and long-term maintenance of sample archives,
records, and data management. In the U.S., state and federal permits are required
to capture, handle, or sample any sea turtle species (which are protected), and to
possess sea turtle tissues or parts. Any activity that results in a “take,” the death or
removal from the free-ranging population, also requires special permits. This
includes euthanasia of moribund and catastrophically injured animals, which could
provide valuable tissues. In many instances, the best material for analysis is obtained
from a freshly euthanized sick animal. Therefore, even though an interesting disease
case may be found, it would be illegal to collect blood or a skin lesion biopsy unless
specifically permitted to do so. Thus, permit issues should be settled before undertaking health studies. In addition, supplies and materials needed to support health
studies and sample collection must be kept in stock and in date for use when required.
1123 book.book Page 407 Monday, November 11, 2002 11:11 AM