Three of the more pressing issues in bird-feeding research are the link between bird-feeding activities and transmission of diseases among birds (e.g. Bradley and Altizer, 2006), the degree to which anthropogenic food serves as a dietary supplement to a diverse array of food items consumed by birds and the degree to which feeders create dependency among bird populations (Brittingham and Temple, 1992; Jones and Reynolds, 2008). Each of these issues, disease transmission in particular, has been considered in existing studies of the impacts of anthropogenic food on wildlife. A recent meta-analysis by Becker et al. (2015) includes excellent evidence-based discussion of the importance of fully evaluating the costs and potential negative impacts of human alteration of the foraging ecology of wildlife and its link with increased disease transmission. Given that some studies show positive impacts of bird-feeding activities, whereas other studies show costs or negative impacts, combined with the knowledge that most bird populations are in decline, it is absolutely crucial that all investigations of the impacts of anthropogenic food on bird health consider benefits and costs alike.
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Several fundamental questions about wild bird feeding remain. In particular, few studies have examined the impact of supplemental food on wild bird populations, including how bird feeding influences the health and energy demands of individual birds and may change the overall bird community (although see Brittingham and Temple, 1988; Geis and Pomeroy, 1993; Pravosudov et al., 2001; Schoech et al., 2004). From spring 2011 to spring 2014, we examined how bird feeding impacts wild birds by evaluating the health of individual birds with a broad range of metrics, including body condition, stress, antioxidant levels, nutritional condition, immune function and disease, by comparing forested sites with and without feeders.
Defining avian health and choosing relevant metrics can be challenging. In many cases, physiological responses are context dependent, and in general, it is unlikely that any single measure is truly representative of the health of a free-living bird. For this reason, we used multiple metrics that measure a diverse array of physiological functions. Body condition has been defined in a very broad sense to indicate the physical make-up of a bird that confers the ability of an individual to cope with present and future physiological stress, and therefore, the ability to enhance fitness (Carrascal et al., 1998). Mass alone is unlikely to serve as a reliable indicator of condition, as an animal can be heavy because it is structurally large or because it is carrying abundant fat or protein (Dobson, 1992); therefore, using measures that consider the structural size and mass, as well as storage of macronutrients such as fat, are important. In general, wild songbirds have very little fat because they need to remain light. However, fat reserves can be important in buffering an animal against fluctuations in food supply or serving as fuel for energetically demanding flight, as in migrating birds (Blem, 1990).
Each bird completes at least one moult per year, dropping each of its feathers and growing a new one in its place. During the regrowth process, a visible growth bar is developed with each day of growth until the feather is fully developed. The assessment of feather growth bar length, or ptilochronology, has been validated in captive and wild birds as a reliable indicator of nutritional condition (Grubb, 1989). Therefore, is likely to serve as a good measure of the impacts of anthropogenic food on bird nutritional condition.
The singing of this song threw the animals into the wildest excitement. Almost before Major had reached the end, they had begun singing it for themselves. Even the stupidest of them had already picked up the tune and a few of the words, and as for the clever ones, such as the pigs and dogs, they had the entire song by heart within a few minutes. And then, after a few preliminary tries, the whole farm burst out into Beasts of England in tremendous unison. The cows lowed it, the dogs whined it, the sheep bleated it, the horses whinnied it, the ducks quacked it. They were so delighted with the song that they sang it right through five times in succession, and might have continued singing it all night if they had not been interrupted.
The ZIP (Zn-regulated, iron-regulated transporter-like protein) transporter plays an important role in regulating the uptake, transport, and accumulation of microelements in plants. Although some studies have identified ZIP genes in wheat, the significance of this family is not well understood, particularly its involvement under Fe and Zn stresses. In this study, we comprehensively characterized the wheat ZIP family at the genomic level and performed functional verification of three TaZIP genes by yeast complementary analysis and of TaZIP13-B by transgenic Arabidopsis. Totally, 58 TaZIP genes were identified based on the genome-wide search against the latest wheat reference (IWGSC_V1.1). They were then classified into three groups, based on phylogenetic analysis, and the members within the same group shared the similar exon-intron structures and conserved motif compositions. Expression pattern analysis revealed that the most of TaZIP genes were highly expressed in the roots, and nine TaZIP genes displayed high expression at grain filling stage. When exposed to ZnSO4 and FeCl3 solutions, the TaZIP genes showed differential expression patterns. Additionally, six ZIP genes responded to zinc-iron deficiency. A total of 57 miRNA-TaZIP interactions were constructed based on the target relationship, and three miRNAs were downregulated when exposed to the ZnSO4 and FeCl3 stresses. Yeast complementation analysis proved that TaZIP14-B, TaZIP13-B, and TaIRT2-A could transport Zn and Fe. Finally, overexpression of TaZIP13-B in Arabidopsis showed that the transgenic plants displayed better tolerance to Fe/Zn stresses and could enrich more metallic elements in their seeds than wild-type Arabidopsis. This study systematically analyzed the genomic organization, gene structure, expression profiles, regulatory network, and the biological function of the ZIP family in wheat, providing better understanding of the regulatory roles of TaZIPs and contributing to improve nutrient quality in wheat crops.
Figure 8. Comparison of the phenotypic performance of three TaZIP13-B overexpression Arabidopsis lines and wild type. (A) The expression level of TaZIP13-B in T3 transgenic Arabidopsis lines. Bars indicate standard deviations of three biological replicates; (B,C) seed germination rate with different treatment; (D,E) root length of WT and three transgenic lines (bar=1cm); (F,G) phenotypic identification of Arabidopsis treated with ZnSO4 and FeCl3 solution, respectively (concentration: 200, 300, 400μmol/L); (H) chlorophyll content; (I) phenotype of stomata; (J,K) seed width and length (bar=1mm, n>30); (L) the content of Zn and Fe in roots, shoots and seeds. Statistically significant differences are indicated: *p 2ff7e9595c
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