282 research outputs found
Tamarisk biocontrol using Tamarisk Beetles: Potential consequences for riparian birds in the southwestern United Stains
The tamarisk beetle (Diorhabda spp.), a non-native biocontrol agent, has been introduced to eradicate
tamarisk (Tamarix spp.), a genus of non-native tree that has become a dominant component of riparian woodlands
in the southwestern United States. Tamarisk beetles have the potential to spread widely and defoliate large
expanses of tamarisk habitat, but the effects of such a widespread loss of riparian vegetation on birds remains unknown. We reviewed literature on the effects of other defoliating insects on birds to investigate the potential for tamarisk beetles to affect birds positively or negatively by changing food abundance and vegetation structure. We then combined data on the temporal patterns of tamarisk defoliation by beetles with nest productivity of a well studied riparian obligate, the Southwestern Willow Flycatcher (Empidonax traillii extimus), to simulate the potential demographic consequences of beetle defoliation on breeding riparian birds in both the short and long term.
Our results highlight that the effects of tamarisk biocontrol on birds will likely vary by species and population, depending upon its sensitivity to seasonal defoliation by beetles and net loss of riparian habitat due to tamarisk mortality. Species with restricted distributions that include areas dominated by tamarisk may be negatively affected both in the short and long term. The rate of regeneration and/or restoration of native cottonwoods (Populus spp.)and willows (Salix spp.) relative to the rate of tamarisk loss will be critical in determining the long-term effect of this large-scale ecological experiment
The State of Internet Access to North Carolina African-American Archival Collections
This study examines the state of online access to African-American archival collections in North Carolina. To measure the relative progress made in providing online access to African-American materials in recent years, as online access to archival materials in general has increased, a survey was conducted that compared current data collected from North Carolina institutions against the information for those same institutions that appears in the Guide to African-American Documentary Resources in North Carolin
Grape seed proanthocyanidins inhibit the invasive potential of head and neck cutaneous squamous cell carcinoma cells by targeting EGFR expression and epithelial-to-mesenchymal transition
<p>Abstract</p> <p>Background</p> <p>Head and neck squamous cell carcinoma (HNSCC) is responsible for over 20,000 deaths every year in United States. Most of the deaths are due, in large part, to its propensity to metastasize. We have examined the effect of bioactive component grape seed proanthocyanidins (GSPs) on human cutaneous HNSCC cell invasion and the molecular mechanisms underlying these effects using SCC13 cell line as an <it>in vitro </it>model.</p> <p>Methods</p> <p>The therapeutic effects of GSPs on cancer cell invasion were studied using Boyden chamber and wound healing assays. The effects of GSPs on the levels of various proteins related with cancer cell invasion were determined using western blot analysis.</p> <p>Results</p> <p>Using <it>in vitro </it>cell invasion assays, we observed that treatment of SCC13 cells with GSPs resulted in a concentration-dependent inhibition of cell invasion of these cells, which was associated with a reduction in the levels of epidermal growth factor receptor (EGFR). Treatment of cells with gefitinib and erlotinib, inhibitors of EGFR, or transient transfection of SCC13 cells with EGFR small interfering RNA, also inhibited invasion of these cells. The inhibition of cell invasion by GSPs was associated with the inhibition of the phosphorylation of ERK1/2, a member of mitogen-activated protein kinase family. Treatment of cells with UO126, an inhibitor of MEK, also inhibited the invasion potential of SCC13 cells. Additionally, inhibition of human cutaneous HNSCC cell invasion by GSPs was associated with reversal of epithelial-to-mesenchymal transition (EMT) process, which resulted in an increase in the levels of epithelial biomarker (E-cadherin) while loss of mesenchymal biomarkers (vimentin, fibronectin and N-cadherin) in cells. Similar effect on EMT biomarkers was also observed when cells were treated with erlotinib.</p> <p>Conclusion</p> <p>The results obtained from this study indicate that grape seed proanthocyanidins have the ability to inhibit the invasion of human cutaneous HNSCC cells by targeting the EGFR expression and reversing the process of epithelial-to-mesenchymal transition. These data suggest that GSPs can be developed as a complementary and alternative medicine for the prevention of invasion/metastasis of HNSCC cells.</p
Variation in Flight Morphology in a Damselfly with Female-Limited Polymorphism
Background: Female-limited colour polymorphisms occur in many species of dragonflies and damselflies. Often one female morph appears male-like in coloration (androchromes) whereas one or more others are distinct from males (gynochromes). These androchromes are hypothesized to be male-mimics, thereby avoiding the harassment of excessive male mating attempts.
Organism: The damselfly Ischnura ramburii, Rambur’s forktail, is a widespread New World species with androchrome and gynochrome females. It was introduced to the Hawaiian Islands in the mid-1970s and females were thought to be exclusively gynochromatic there.
Questions: How do males and females differ in their flight apparatus? Do females with different colour morphologies also differ in flight morphology? Hypothesis: Because male-like coloration is sometimes associated with male-like flight behaviours, androchrome females should have more male-like wings than gynochrome females.
Methods: We caught individuals of I. ramburii in the field from seven populations on three of the Hawaiian Islands and three populations in Texas (part of its native range). Using digitized wing and body images, we compared body size, wing size, and wing shape between sexes, between female morphs, and among geographic regions.
Results: Male I. ramburii are smaller than females and have smaller, more slender wings. Although androchromes are absent from the Big Island of Hawaii, both androchrome and gynochrome females are common on Oahu and Kauai. Androchrome females are indistinguishable from gynochrome females in all aspects of their flight apparatus except for forewing size, which is smaller than that of gynochromes and thus more-male like. Wing shape and size vary geographically. Body- and wing-size differences between males and females are consistent across regions, although the degree and direction of sexual dimorphism in wing shape are not
Age, habitat, and yearly variation in the diet of a generalist insectivore, the Southwestern Willow Flycatcher
The article presents a study which examines the age, habitat, and yearly variation in the diet of a generalist insectivore, the southwestern Willow Flycatcher at Roosevelt Lake in central Arizona. It focuses on the five prey categories which were accounted for 70% of the proportional abundance in flycatcher diet, including Hymenoptera, Diptera, Cicadellidae, Coleoptera, and Formicide. It states that there were no detected differences in diet between sexes of adults, but adults and nestling samples differed, with higher proportions of Hymenoptera in adult samples and more Diptera in nestling samples. It discusses the comparison between flycatcher diet in habitat patches dominated by native cottonwood and willow, exotic salt cedar, or a mix of the three species
Winter distribution of willow flycatcher subspecies
The article presents a study which examines the migratory connectivity in the Willow Flycatcher subspecies throughout the winter range using mitochondrial DNA sequences as well as the morphological characteristics of 68 museum specimens obtained in the winter range in Costa Rica. It notes that the findings reveal that the overlapping and distinct regions of the winter range were occupied by the four subspecies. The specific breeding of these species is connected to the winter grounds
Genetic variation in the endangered Southwestern Willow Flycatcher
The Southwestern Willow Flycatcher (Empidonax traillii extimus) is an endangered Neotropical migrant that breeds in isolated remnants of dense riparian habitat in the southwestern United States. We estimated genetic variation at 20 breeding sites of the Southwestern Willow Flycatcher (290 individuals) using 38 amplified fragment length polymorphisms (AFLPs). Our results suggest that considerable genetic diversity exists within the subspecies and within local breeding sites. Statistical analyses of genetic variation revealed only slight, although significant, differentiation among breeding sites (Mantel's r = 0.0705, P < 0.0005; theta = 0.0816, 95% CI = 0.0608 to 0.1034; Phi sub(ST) = 0.0458, P < 0.001). UPGMA cluster analysis of the AFLP markers indicates that extensive gene flow has occurred among breeding sites. No one site stood out as being genetically unique or isolated. Therefore, the small level of genetic structure that we detected may not be biologically significant. Ongoing field studies are consistent with this conclusion. Of the banded birds that were resighted or recaptured in Arizona during the 1996 to 1998 breeding seasons, one-third moved between breeding sites and two-thirds were philopatric. Low differentiation may be the result of historically high rangewide diversity followed by recent geographic isolation of breeding sites, although observational data indicate that gene flow is a current phenomenon. Our data suggest that breeding groups of E. t. extimus act as a metapopulation
Analisis Penyuluhan dan Keberdayaan Petani Karet Pola Swadaya di Kabupaten Rokan Hilir, Provinsi Riau
Penelitian ini bertujuan : (1) mendeskripsikan peran penyuluhan terhadap petani karet pola swadaya; (2) mendeskripsikan tingkat keberdayaan petani; (3) mendeskripsikan tingkat ketercapaian tujuan penyuluhan; (4) menganalisis pengaruh peran penyuluhan terhadap keberdayaan; (5) menganalisis pengaruh keberdayaan terhadap ketercapaian tujuan penyuluhan. Penelitian ini dilaksanakan di Kecamatan Pujud dan Kecamatan Tanah Putih Kabupaten Rokan Hilir. Responden penelitian ditentukan menggunakan metode key informan sampling dengan jumlah responden sebanyak 118. Untuk menjawab tujuan pertama, kedua, dan ketiga dari penelitian ini menggunakan likert's scale summated rating (SLR). Untuk menjawab tujuan keempat dan kelima menggunakan structural equation modeling (SEM) dengan program AMOS. Hasil penelitian menunjukkan bahwa (1) peran penyuluhan cukup berperan terhadap USAha tani petani karet pola swadaya; (2) tingkat keberdayaan petani di kategorikan berdaya; (3) tujuan penyuluhan telah tercapai yang dilihat dari better farming, better business, dan better living; (4) peran penyuluhan terbukti berpengaruh secara signifikan terhadap tingkat keberdayaan petani; (5) tingkat keberdayaan petani terbukti berpengaruh signifikan terhadap tercapainya tujuan penyuluhan
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