Shifts in the Holstein dairy cow milk fat globule membrane proteome that occur during the first week of lactation are affected by parity

Background:The milk fat globule membrane(MFGM)proteomes of colostrum and transition milk are rich sources of proteins that are likely important for neonatal calf health.In addition,characterization of these proteomes could also yield valuable information regarding mammary gland physiology of the early postpartum lactating cow.The objectives of this research were to characterize the MFGM proteomes of colostrum and transition milk through sample collections at four timepoints postpartum,including the first milking(M1,colostrum),second milking(M2,transition milk),fourth milking(M4,transition milk),and fourteenth milking(M14,mature milk),and compare these proteomes between multiparous(MP;n=10)and primiparous(PP;n=10)Holstein dairy cows.Isolated MFGM proteins were labeled using Tandem Mass tagging and analyzed using liquid chromatography-tandem mass spectrometry(LC-MS/MS).Protein identification was completed using MASCOT and Sequest in Proteome Discoverer 2.2.The scaled abundance values were analyzed using PROC MIXED in SAS to determine the effects of milking(MIL),parity(PAR),and MIL×PAR.The adaptive false-discovery rate(FDR)-adjusted P values were determined using PROC MULTTEST.Protein characterization and bioinformatic analysis were completed using a combination of PANTHER,Blast,and Uniprot.Results:A total of 104 common proteins were identified in each of the MFGM samples.Statistical analysis revealed that 70.2%of identified proteins were affected by MIL.Of these,78.1%were lower in M14 compared with M1,including immune-related proteins lactotransferrin,lactadherin and hemopexin.Parity affected 44.2%of proteins.Of the proteins affected by PAR,84.8%were higher in MP cows compared with PP cows,including apolipoprotein E and histones 2A,2B,3,and 4 b.Butyrophilin subfamily 1 member 1A and annexin 5 were higher in samples from PP cows.Milking×parity affected 32.7%of identified proteins,including lactotransferrin,gelsolin,vitamin D binding protein,and S100 proteins.Conclusions:This research supports previous findings that the Holstein MFGM proteome changes rapidly during the first week of lactation.In addition,this research identifies the impact of parity on the colostrum and transition milk MFGM proteomes,which may be important for milk-fed calf health or for the identification of protein biomarkers for mammary functionality.

Scatterhoarding rodents favor higher predation risks for cache sites:The potential for predators to influence the seed dispersal process

Scatterhoarding rodents often place caches in the open where pilferage rates are reduced,suggesting that they tradeoff higher risks of predation for more secure cache sites.We tested this hypothesis in two study systems by measuring predation risks inferred from measures of giving-up densities(GUDs)at known cache sites and other sites for comparison.Rodent GUDs were measured with small trays containing 3 L of fine sand mixed with sunflower seeds.In the first experiment,we relied on a 2-year seed dispersal study in a natural forest to identify caches of eastern gray squirrels(Sciurus carolinensis)and then measured GUDs at:(i)these caches;(ii)comparable points along logs and rocks where rodent activity was assumed highest;and(iii)a set of random points.We found that GUDs and,presumably,predation risks,were higher at both cache and random points than those with cover.At the second site,we measured GUDs of eastern gray squirrels in an open park system and found that GUDs were consistently lowest at the base of the tree compared to more open sites,where previous studies show caching by squirrels to be highest and pilferage rates by naïve competitors to be lowest.These results confirm that predation risks can influence scatterhoarding decisions but that they are also highly context dependent,and that the landscape of fear,now so well documented in the literature,could potentially shape the temporal and spatial patterns of seedling establishment and forest regeneration in systems where scatterhoarding is common.

Effects of insect infestation on rodent-mediated dispersal of Quercus aliena:results from field and enclosure experiments

Rodents influence plant establishment and regeneration by functioning as both seed predators and dispersers.However,these rodent-plant interactions can vary significantly due to various environmental conditions and the activity of other insect seed predators.Here,we use a combination of both field and enclosure(i.e.individual cage and semi-natural enclosure)experiments,to determine whether rodents can distinguish sound seeds from those infested with insects.We also demonstrate how such responses to insects are influenced by food abun-dance and other environmental factors.We presented rodents with 2 kinds of Quercus aliena seeds(sound and insect-infested seeds)in a subtropical forest in the Qinling Mountains,central China,from September to No-vember of 2011 to 2013.The results showed that rodents preferred to hoard and eat sound seeds than infested seeds in the field and semi-natural enclosure,while they preferred to eat infested seeds over sound seeds in the individual cages.In addition,both hoarding and eating decisions were influenced by food abundance.Rodents hoarded more sound seeds in years of high food abundance while they consumed more acorns in years of food shortage.Compared with field results,rodents reduced scatter-hoarding behavior in semi-natural enclosures and ate more insect-infested seeds in smaller individual cages.These results further confirm that rodents distinguish infested seeds from non-infested seeds but demonstrate that this behavior varies with conditions(i.e.environ-ment and food abundance).We suggest that such interactions will influence the dispersal and natural regenera-tion of seeds as well as predation rates on insect larvae.

Invasive oaks escape pre-dispersal insect seed predation and trap enemies in their seeds

Species introduced to habitats outside their native range often escape control by their natural enemies.Besides competing with native species,an alien species might also affect the native herbivores by introducing a new source of different quality food.Here,we describe the case of northern red oak(Quercus rubra)invasion in Europe.We collected data on insect(moth Cydia spp.and weevil Curculio spp.)seed predation of northern red oak in its native(USA,North America)and invasive(Poland,Europe)range,as well as for sessile oaks(Quercus petrea)in Europe.We also evaluated the quality of acorns as hosts for weevil larvae by collecting infested acorns and measuring weevil developmental success,and quantifying acorn traits such as seed mass,tannins,lipids and protein concentration.We used DNA barcoding to identify insects to the species level.The predation by moths was similar and very low in both species and in both ranges.However,red oaks escape pre-dispersal seed predation by weevils in Europe.Weevil infestation rates of northern red oak acorns in their invasive range were 10 times lower than that of sessile oaks,and also 10 times lower than that of red oaks in North America.Furthermore,even when weevils oviposited into northern red oaks,the larvae failed to develop,suggesting that the exotic host created a trap for the insect.This phenomenon might gradually decrease the local abundance of the seed predator,and further aid the invasion.

Plant-animal interactions: patterns and mechanisms in terrestrial ecosystems

From the early work of Darwin,then Ehrlich and Raven(1964),to the recent novel contribution of mutualistic networks developed by Jordano and colleagues(Bascompte and Jordano 2007,Nuismer et al.2013,Guimarães et al.2017),it is clear that plant-animal interactions—especially those involving herbivory,seed dispersal,seed predation and pollination—are significant drivers of ecological processes and the evolution and maintenance of biodiversity.The vast majority of plant species,for example,are influenced by animal-mediated seed dispersal and pollination.

Seed traits and rodent community interact to determine seed fate:evidence from both enclosure and field experiments

Animal-mediated seed dispersal is an important ecological process in which a strong mutualism between animals and plants can arise.However,few studies have examined how a community of potential seed dispersers interacts with sympatric seed trees.We employed a series of experiments in the Qinling Mountains in both semi-natural enclosure and the field to assess the interactions among 3 sympatric rodent species and 3 Fagaceae tree seeds.Seed traits all showed similar tannin levels but markedly different physical traits and nutritional contents.We found that seeds with heavy weight,thick coat,and high nutritional contents were less likely to be eaten in situ but more often to be eaten after dispersal or hoarded by rodents.These results support both the handling time hypothesis and the high nutrition hypothesis.Surprisingly,we also found that rodents,maybe,preferred to consume seeds with low levels of crude fiber in situ,and to harvest and hoard those with high levels of crude fiber for later consumption.The sympatric rodent species,Cansumys canus,the largest rodent in our study,harvested and hoarded more Quercus variabilis seeds with high physical and nutritional traits,while Apodemus draco,the smallest rodent,harvested more Q.serrata seeds with low physical and nutritional traits,and Niviventer confucianus harvested and hoarded more Q.aliena seeds with medium physical and nutritional traits.Our study demonstrates that different seed traits play different roles in influencing the seed fate and the shaping of mutualism and predation interactions within a community of rodent species.

Environmental variation shifts the relationship between trees and scatterhoarders along the continuum from mutualism to antagonism

The conditional mutualism between scatterhoarders and trees varies on a continuum from mutualism to antagonism and can change across time and space,and among species.We examined 4 tree species(red oak[Quercus rubra],white oak[Quercus alba],American chestnut[Castanea dentata]and hybrid chestnut[C.dentata×Castanea] mollissima)across 5 sites and 3 years to quantify the variability in this conditional mutualism.We used a published model to compare the rates of seed emergence with and without burial to the probability that seeds will be cached and left uneaten by scatterhoarders to quantify variation in the conditional mutualism that can be explained by environmental variation among sites,years,species,and seed provenance within species.All species tested had increased emergence when buried.However,comparing benefits of burial to the probability of caching by scatterhoarders indicated a mutualism in red oak,while white oak was nearly always antagonistic.Chestnut was variable around the boundary between mutualism and antagonism,indicating a high degree of context dependence in the relationship with scatterhoarders.We found that different seed provenances did not vary in their potential for mutualism.Temperature did not explain microsite differences in seed emergence in any of the species tested.In hybrid chestnut only,emergence on the surface declined with soil moisture in the fall.By quantifying the variation in the conditional mutualism that was not caused by changes in scatterhoarder behavior,we show that environmental conditions and seed traits are an important and underappreciated component of the variation in the relationship between trees and scatterhoarders.

Does multiple seed loading in Blue Jays result in selective dispersal of smaller acorns?

Studies from both tropical and temperate systems show that scatter-hoarding rodents selectively disperse larger seeds farther from their source than smaller seeds,potentially increasing seedling establishment in larger-seeded plants.Size-biased dispersal is evident in many oaks(Quercus)and is true both across and within species.Here,we predict that intraspecifc variation in seed size also influences acorn dispersal by the Blue Jay(Cyanocitta cristata Linnaeus),but in an opposite manner.Blue Jays are gape-limited and selectively disperse smaller acorn species(e.g.pin oaks[Quercus palustris Münchh]),but often carry several acorns in their crop during a single dispersal event.We predict that jays foraging on smaller acorns will load more seeds per trip and disperse seeds to greater distances than when single acorns are carried in the bill.To test this,we presented free-ranging Blue Jays with pin oak acorns of different sizes over a 2-year period.In each of 16 experimental trials,we monitored the birds at a feeding station with remote cameras and determined the number of acorns removed and the distance acorns were dispersed when cached.Jays were significantly more likely to engage in multiple seed loading with smaller seeds in both years of the study.During the second year,these smaller acorns were dispersed farther than larger acorns,and during the first year,larger acorns were dispersed farther,revealing an inconsistent response to seed size during our study.We suggest that in some circumstances,multiple seed loading by Blue Jays may favor dispersal in some plant species.

Frugivory and seed dispersal:integrating patterns, mechanisms and consequences of a key animal-plant interaction

The study of frugivory and seed dispersal is both excit-ing and challenging because it integrates research from multiple biological disciplines,including zoology,botany,physiology,behavioral ecology,evolution,conservation,and population and community ecology.At the center of these investigations is one of the most important mutual-istic relationships hypothesized to organize and maintain diversity in terrestrial ecosystems:the movement of plant seeds by fruit and seed-eating animals(Bascompte&Jordano 2007).Although recent studies on the seed dis-persal process have advanced the breadth and depth of our understanding of this keystone interaction,many ques-tions are still unanswered.A clear synthesis and theoreti-cal framework for integrating what we do know also re-mains elusive.Moreover,the imperative to better under-stand the movement of organisms in the face of human-induced global changes has sparked an additional need for seed dispersal studies(Wang&Smith 2002;Bullock&Nathan 2008;Nathan et al.2008).

An Integrative Look at Frugivory and Seed Dispersal Studies

The declaration of 2010 as the International Year of Biodiversity by the United Nations’General Assembly was a recognition of the reality and gravity of the current biodiversity crisis,an episode in earth’s history that many now consider the 6th Mass Extinction(Wake&Vredenburg 2008).Human-driven loss of biodiversity refers not only to the loss of species,populations,and genetic diversity,but also to the loss of ecological interactions that are central to ecosystem function(Tylianakis et al.2008).