Research in the Hood lab focuses on understanding the interactions between nutrition and energetics, physiology, and individual differences in age at first reproduction, reproductive performance, and longevity. Within this context, most of our project fall into 3 categories: 1) reproductive performance and life history tradeoffs, 2) maternal effects and offspring performance, and 3) milk composition and the impact of lactation on human health.
The Hood lab is currently funded by an NSF CAREER grant to Hood, an NSF EPSCoR grant with Kiaris at USC, and an NIH R03 to Hood and Kavazis, Click here to read abstracts of these projects.
What is Nutritional Ecology?
We often describe our research as fitting within the context of nutritional ecology. Sometimes when we describe ourselves as nutritional ecologists, folks respond with a puzzled look. The following [link here] explains our definition of this growing and exciting avenue of research.
Reproductive performance and life history tradeoffs
We are currently evaluating the role that mitochondria plays in the tradeoff between reproduction and longevity in house mice. This work is done in collaboration with Dr. Andreas Kavazis, School of Kinesiology, Auburn University.
In prior studies:
We have shown that the availability of calcium to mammalian mothers can impact bone loss in mothers, mineral transfer to young, and offspring sex ratio in white-footed mice and big brown bats.
And, we have shown that cannibalism reduces bone loss during lactation in lab mice.
Maternal effects and offspring performance
We use a unique model for examining the impacts of maternal effects on the physiology and fitness of wild animals based on maintaining house mice in semi-natural populations. We are currently examining the effect of maternal protein intake on offspring physiology and reproductive fitness in these mice. The physiological variables we are evaluating include RMR, IGF-1, corticosterone, and cort receptor expresssion.
We have also examined the impact of calcium, vitamin D, and stress on development in bluebirds – these analyses are current in progress.
Milk composition and the impact of lactation on human health
We are currently describing the impact of a mothers diet on her milk microbiota in house mice and lab rats in collaboration with Dr Mark Liles.
We are evaluting the impact of lactation on cellular metabolism and mitochondrial function. In humans, women who do not nurse their babies have a higher statistical probability of obesity, diabetes, and cancer than women who forgo nursing. In collaboration with Dr. Kavazis, we are initiating a study that will test the 'lactation reset hypothesis', or the theory that lactation undoes the changes in metabolism that occur during pregnancy, bringing cellular function back to a pre-pregnancy state. This work will be completed in rats.
In prior studies:
We have described milk composition for several species including naked-mole rats, Columbian ground squirrels, and several species of bats.
We have shown that the composition of a mothers milk composition impacts offspring survival in Columbian ground squirrels.
We completed the first phylogenetically corrected statistical analysis of milk composition across vertebrates, allowing to us describe factors that contribute to the evolution of milk composition.
The house mouse in the mouse house
We study wild-derived house mice kept in enclosures that mimic the ambient conditions, home range and group sizes that house mice experience living in the wild. This is a great model for evaluting the long-term and transgenerational impacts of environmental variables, such as diet, on physiology and reproductive performance. This model also allows us to build on the wealth of biomedical studies that have been conducted on physiology of lab mice and it allows us collect data in a setting that will help us to understand processses in wild populations. We set up our facility in collaboration with Dr. Wayne Potts, University of Utah.
Mitochondrial function and oxidative damage
Oxidative phosphoryation (OXPHOS) with the inner mitochondrial membrane is responsible for producing ATP and reactive oxygen species (ROS), products that support life (ATP) and may ultimately contribute to its demise (via ROS damage and/or mtDNA mutation). Although there is little debate that OXPHOS plays a role in indivudal variation in rate of growth, reproductive performance, and senscence, exactly how the mitochondria contribute this variation and their interactions is remains poorly understood and is a current focus of our research. Our work on mitochondria function is done in collaboration with Dr. Kavazis.
Milk provides offspring with a nutritionally complete diet that has evolved to meet each mammalian species unique requirements for growth and development. In addition, milk includes a rich community of microbiota that contribute to the microbial colonization of the offspring gut and variety of hormones and other bioactive factors that provide offspring with information about the environment that experience at independence.
We are adept a collecting milk, quantifying milk compostion, and measuring milk production and have a nack for completing these measurements in small species. We are currently learning techniques for evaluating microbial diversity in milk.
Bone mineral composition and strength
During late pregnancy and lactation, mammalian mothers must supply their young with enough mineral (notably Ca and P) to support the ossification of their offsprings' sketetons. In many cases, females do so by mobilizing mineral from their own bone, a process that reduces their bone strength. We are interested what dictates this tradeoff between investment in self and the next generation. Bone provides a tractable system for evaluating this tradeoff because 99% of the body's calcium occurs in bone and the negative impact of bone loss (bone strength testing) are easilly quantifiable.