Adaptation of sea turtles to climate warming: Will phenological responses be sufficient to counteract changes in reproductive output?

Sea turtles are vulnerable to climate change since their reproductive output is influenced by incubating temperatures, with warmer temperatures causing lower hatching success and increased feminization of embryos. Their ability to cope with projected increases in ambient temperatures will depend on their capacity to adapt to shifts in climatic regimes. Here, we assessed the extent to which phenological shifts could mitigate impacts from increases in ambient temperatures (from 1.5 to 3°C in air temperatures and from 1.4 to 2.3°C in sea surface temperatures by 2100 at our sites) on four species of sea turtles, under a "middle of the road" scenario (SSP2-4.5). Sand temperatures at sea turtle nesting sites are projected to increase from 0.58 to 4.17°C by 2100 and expected shifts in nesting of 26-43 days earlier will not be sufficient to maintain current incubation temperatures at 7 (29%) of our sites, hatching success rates at 10 (42%) of our sites, with current trends in hatchling sex ratio being able to be maintained at half of the sites. We also calculated the phenological shifts that would be required (both backward for an earlier shift in nesting and forward for a later shift) to keep up with present-day incubation temperatures, hatching success rates, and sex ratios. The required shifts backward in nesting for incubation temperatures ranged from -20 to -191 days, whereas the required shifts forward ranged from +54 to +180 days. However, for half of the sites, no matter the shift the median incubation temperature will always be warmer than the 75th percentile of current ranges. Given that phenological shifts will not be able to ameliorate predicted changes in temperature, hatching success and sex ratio at most sites, turtles may need to use other adaptive responses and/or there is the need to enhance sea turtle resilience to climate warming.

The carboxyl-terminal domain of type VII collagen is present at the basement membrane in recessive dystrophic epidermolysis bullosa.

Recent studies showing that type VII collagen is a component of anchoring fibrils suggests that the absence of anchoring fibrils in recessive dystrophic epidermolysis bullosa may be due to a defect in the synthesis, secretion, and deposition of type VII collagen. That hypothesis is further supported by recent studies suggesting that monoclonal antibodies to type VII collagen do not react with the basement membrane in most patients. To investigate further, we examined skin from 12 patients by electron microscopy and by immunohistology and immunoelectron microscopy using a concentrated and purified monoclonal antibody to the carboxy-terminal domain of Type VII collagen. Although anchoring fibrils were not detected by electron microscopy, the results of immunohistology showed definite, but reduced, binding of the monoclonal antibody to type VII collagen at the basement membrane in a linear pattern in 11 of 12 patients. By immunoelectron microscopy, reduced deposition of anti-type VII collagen antibody was detected beneath the lamina densa. The results of this study show that the carboxyl-terminal domain of type VII collagen is synthesized, secreted, and deposited at the basement membrane zone in 11 of 12 patients with recessive dystrophic epidermolysis bullosa and suggest that the absence of anchoring fibrils may be due either to deposition of abnormal type VII collagen, reduced levels of normal type VII collagen, defective assembly of type VII collagen into anchoring fibrils, or destruction of the collagenous domain of type VII collagen.

Covalent attachment of 125I-beta nerve growth factor to its receptors on sympathetic neurons.

When 125I-beta nerve growth factor binds to sympathetic and sensory neurons, some labeled ligand is sequestered (becomes inaccessible to the external milieu) in a time- and energy-dependent manner. It would appear that the higher affinity receptor (type I) participates in this process to a greater extent than does the lower affinity receptor (type II) [ Olender and Stach , 1980; Olender et al., 1981]. A small portion of the sequestered 125I-beta nerve growth factor is found as part of a high molecular weight complex. When cells, which have been incubated with 125I-beta nerve growth factor, are solubilized with Triton X-100 and subjected to sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis, a complex with an apparent molecular weight of approximately 240,000 is obtained. The formation of the covalent complex can be prevented by the prior addition of excess unlabeled beta nerve growth factor or sodium fluoride and dinitrophenol. The covalent 125I-beta nerve growth factor-receptor complex is dissociated in 50 mM dithiothreitol indicating that disulfide linkages are involved. At concentrations of beta nerve growth factor (3.8 X 10(-11) -3.8 X 10(-10) M) where maximal fiber outgrowth occurs in vitro, approximately 50-266 attomoles (0.3-1.6% of the type I receptors) of the covalent complex are formed per 10(7) nerve cells. These data suggest that a small portion of the 125I-beta nerve growth sequestered by sympathetic neurons becomes covalently attached to its receptor subsequent to its sequestration in a manner which appears to involve type I receptors.

Serum-free culture of chicken embryonic sensory ganglia in a balanced salt solution with nerve growth factor for periods up to two weeks.

Culture of embryonic chicken dorsal root ganglia for periods exceeding a week generally require serum supplementation and a trophic factor such as nerve growth factor. In this communication we describe the culture of chicken E-9 dorsal root ganglia for periods up to 2 weeks in a system that is composed only of a simple basic salts solution and 10 ng/ml (3.8 X 10(-10)M) beta nerve growth factor. Commercially available tissue culture dishes are used which have a hydrophilic, gas-diffusable membrane on the bottom to which the ganglia directly attach, eliminating the need for added substratum. Sparse fiber outgrowth appears after 24 hours and growth of the fibers continues for 120 hours of incubation. At this time, the fibers are extremely dense and reach approximately 3.5-4.0 diameters from the body of the ganglion. Continued survival of these fibers appears to depend on the concentration of nonneuronal cells present in the dish. No fiber outgrowth occurs at any time in the absence of beta nerve growth factor. The simplicity and purity of this culture system makes it an attractive tool in the study of primary cell-cell interactions, the production of trophic factors by nonneuronal cells, and biochemical and physiological analyses of growing neurons.

Interaction of [125I] beta nerve growth factor with acidic proteins.

We have demonstrated that the beta nerve growth factor will interact with various acidic proteins apparently nonspecifically. When 125I-labeled beta nerve growth factor at a concentration of 3.8 X 10(-10) M is incubated with an acidic protein at 2 mg/ml (4.5 X 10(-6)-4.4 X 10(-5) M), a complex is formed. This complex changes the isoelectric point of the 125I-labeled beta nerve growth factor sufficiently so that the 125I-labeled beta nerve growth factor migrates anomalously in polyacrylamide gel electrophoresis. The interaction between beta nerve growth factor and bovine serum albumin, which appears to be complex, may be the cause of the previously reported activation of the beta nerve growth factor when bovine serum albumin is present in a typical bioassay.