Three heat shock proteins are essential for rotifer thermotolerance

Heat shock proteins (HSPs) are important molecules in the stress response of organisms from prokaryotes to mammals, and thus may be useful biomarkers for environmental stress. Here we characterize the functional roles of genes belonging to four distinct families of HSPs (hsp40, hsp60, hsp70, and hsp90) in the monogonont rotifer Brachionus manjavacas. Because B. manjavacas inhabits ponds of varying thermal regimes, including ephemeral ponds that may experience temperature fluctuations, HSP-mediated thermotolerance likely is important to its survival and adaptation. Using interference RNA (RNAi), we provide the first conclusive evidence that HSPs are required for rotifer survival following heat stress. Effective RNAi-mediated suppression of all hsp genes except hsp90 was verified via quantitative PCR. Hsp40, hsp60, and hsp70 are required for rotifer thermotolerance (P < 0.05); however, our data do not indicate hsp90 is essential. Quantitative PCR further revealed immediate up-regulation of hsp40 mRNA following heat stress. Additionally, we demonstrated expression of hsp40 mRNA in multiple tissues using fluorescent in situ hybridization. Our characterization of mRNA expression and functional roles for four distinct hsp genes provides a baseline for molecular-level comparisons of the stress response of rotifers with other taxonomic groups, and the technique for in-depth studies of the role of specific genes in rotifer stress responses. Considering the potential for ambient temperatures to impact species survival, competitive interactions, and body size of individuals, thermotolerance may be an important influence on zooplankton community structure.     

IGF and myostatin pathways are respectively induced during the earlier and the later stages of skeletal muscle hypertrophy induced by clenbuterol,a β2‐adrenergic agonist

Clenbuterol, a β₂‐adrenergic agonist, increases the hypertrophy of skeletal muscle. Insulin‐like growth factor (IGF) is reported to work as a potent positive regulator in the clenbuterol‐induced hypertrophy of skeletal muscles. However, the precise regulatory mechanism for the hypertrophy of skeletal muscle induced by clenbuterol is unknown. Myostatin, a member of the TGFβ super family, is a negative regulator of muscle growth. The aim of the present study is to elucidate the function of myostatin and IGF in the hypertrophy of rat masseter muscle induced by clenbuterol. To investigate the function of myostatin and IGF in regulatory mechanism for the clenbuterol‐induced hypertrophy of skeletal muscles, we analysed the expression of myostatin and phosphorylation levels of myostatin and IGF signaling components in the masseter muscle of rat to which clenbuterol was orally administered for 21 days. Hypertrophy of the rat masseter muscle was induced between 3 and 14 days of oral administration of clenbuterol and was terminated at 21 days. The expression of myostatin and the phosphorylation of smad2/3 were elevated at 21 days. The phosphorylation of IGF receptor 1 (IGFR1) and akt1 was elevated at 3 and 7 days. These results suggest that myostatin functions as a negative regulator in the later stages in the hypertrophy of rat masseter muscle induced by clenbuterol, whereas IGF works as a positive regulator in the earlier stages. Copyright © 2012 John Wiley & Sons, Ltd.     

Folivory by a tropical tanager: species of plants used and the relationship between leaf consumption and fruit abundance

ABSTRACT Folivory, or eating leaves, is unusual for small passerines. Puerto Rican Spindalises (Spindalis portoricensis, Thraupidae), tanagers endemic to the island of Puerto Rico, are known to feed on leaves, but little is known about the possible importance of leaves in their diet. Our objectives were to determine the different species of leaves eaten, the percentage of their diet consisting of leaves, and the relationship between leaf consumption and fruit abundance. We used data from previous studies where the foraging activity of Puerto Rican Spindalises was systematically sampled, and from additional observations made throughout the island. We documented 160 records of folivory, with spindalises feeding on 44 plant species in 25 plant families, including monocots, dicots, gymnosperms, and pteridophytes. Spindalises fed on young leaves of 26 plant species, and mature leaves of 19 plant species. Spindalises were primarly frugivorous (83.9% of diet), but leaves were the second most frequent food item in their diets (8.9% of diet). We also found that leaf consumption was negatively correlated with the abundance of ripe fruit, suggesting that leaves were particularly important food items when less fruit was available. The frequency of folivory by spindalises in our study was less than reported for other folivorous passerines such as plantcutters (Phytotoma spp.) and saltators (Saltator spp.). Nonetheless, folivory may help spindalises cope with human‐dominated landscapes and other environmental changes on small islands.     

Numbered neck collars for long‐distance identification of parakeets

ABSTRACT Most parakeets, parrots, and cockatoos are difficult to mark because of their strong beaks and ability to manipulate items with their feet. We developed a marking method that consists of a numbered tag hung on a neck collar. We used this method to successfully monitor Monk Parakeets (Myiopsitta monachus) and Ring‐necked Parakeets (Psittacula krameri) in Barcelona, Spain, from 2003 to 2009. We marked 881 Monk Parakeets and 88 Ring‐necked Parakeets with collars. Fifteen tags placed on adult Monk Parakeets in 2003 (N= 57) lasted until 2008 and nine until 2009. Three of 12 Ring‐necked Parakeets marked in 2003 were resighted in 2008. We estimated that 4.5% of Monk Parakeets and 5.8% of Ring‐necked Parakeets lost their tags, with median intervals between attachment and tag loss of 347 and 370 d, respectively. Behavioral observations revealed no differences in the time budgets of marked and unmarked Monk Parakeets. In addition, the mass of marked Monk Parakeets did not change between successive recaptures. These results suggest that neck collars had no adverse effects on the birds. Neck collars may also be a suitable marking method for other psittacines, with stronger, more durable components likely needed for larger species.     

Islands within islands: a molecular phylogenetic study of the Leucocroton alliance (Euphorbiaceae) across the Caribbean Islands and within the serpentinite archipelago of Cuba

Aim Our aim was to investigate the historical biogeography of the three genera of the Leucocroton alliance (i.e. Garciadelia Jestrow & Jiménez Rodr., Lasiocroton Griseb., and Leucocroton Griseb., Euphorbiaceae). Location  The alliance is restricted to the Bahamas, Cuba, Hispaniola and Jamaica. Methods Members of the Leucocroton alliance, along with representatives from tribe Adelieae (Adelia L. and Philyra Klotzsch.), were included in a molecular phylogenetic analysis based upon nucleotide sequences of the internal transcribed spacer region of the nuclear ribosomal DNA and the non‐coding chloroplast regions psbM–trnD and ycf6–pcbM. The program s‐diva was used to calculate ancestral areas based on the phylogenetic trees and present species distributions. Results Phylogenetic analyses support the monophyly of the three genera. The ancestral area of the Leucocroton alliance is eastern Cuba and Hispaniola. Ancestral forms of Leucocroton arose on eastern Cuba and underwent two migrations across the island. The ancestor of Lasiocroton also originated on eastern Cuba followed by later dispersal to and speciation events on the other islands. Our study also suggests that ancestral forms of the Leucocroton alliance probably occurred on limestone soils. Main conclusions Our study concurs with previous hypotheses suggesting that the flora of serpentinite regions of the Caribbean derives from other types of soils. The serpentine endemics of the Leucocroton alliance have a single origin and represent one of the most extraordinary examples of speciation in this unique environment of the New World. The high colonization success achieved by the members of Leucocroton on serpentine soils was not attained by the other genera of the alliance, which occur on limestone areas.