Hasil untuk "Biology"

V. Schultz, N. T. J. Bailey

D. Bliss

B. Lindenbach, Charles M. Rice

H. Väänänen, Haibo Zhao, M. Mulari et al.

C. Ryall

P. Mundel, S. Shankland

R. Yehuda

R. Iozzo

Jin Zhang, R. Campbell, A. Ting et al.

R. Touyz, E. Schiffrin

C. Fattman, L. Schaefer, T. Oury

J. Blondel, J. Aronson

M. Robertson

Natural killer (NK) cells participate in innate and adaptive immuneresponses to obligate intracellular pathogens and malignant tumors. Twomajor NK cell subsets have been identified in humans:CD56dim CD16+ and CD56bright CD16−. RestingCD56dim CD16+ NK cells express CXCR1, CXCR2, CXCR3, CXCR4,and CX3CR1 but no detectable levels of CC chemokine receptors on thecell surface. They migrate vigorously in response to CXCL12 and CXC3L1.In contrast, resting CD56bright CD16− NK cells expresslittle CXCR1, CXCR2, and CXC3R1 but high levels of CCR5 and CCR7. Chemotaxis of CD56bright CD16− NK cells is stimulated mostpotently by CCL19, CCL21, CXCL10, CXCL11, and CXCL12. Followingactivation, NK cells can migrate in response to additional CC and CXCchemokines. Cytolytic activity of NK cells is augmented by CCL2, CCL3,CCL4, CCL5, CCL10, and CXC3L1. Moreover, proliferation of CD56dim CD16+ NK cells is costimulated by CCL19 and CCL21. Activated NK cells produce XCL1, CCL1, CCL3, CCL4, CCL5, CCL22, andCXCL8. Chemokines secreted by NK cells may recruit other effector cellsduring immune responses. Furthermore, CCL3, CCL4, and CCL5 produced byNK cells can inhibit in vitro replication of HIV. CCL3 and CXL10expression appear to be required for protective NK cell responses invivo to murine cytomegalovirus or Leishmania major,respectively. Moreover, NK cells participate in the in vivo rejectionof transduced tumor cells that produce CCL19 or CCL21. Thus, chemokinesappear to play an important role in afferent and efferent NK cellresponses to infected and neoplastic cells.

Ermelinda Gjeta, Diellëza Lajçi, Avni Hajdari et al.

Populations of Anthyllis vulneraria ssp. vulneraria and A. vulneraria ssp. vallesiaca are found in close vicinity in Val Piora, where the geological situation changes abruptly between basic and acidic substrates. At three sites with populations of A. vulneraria s. lato, one in basic soil, one in acidic soil, and one in a mixed area, three samples of a total of sixty plants were collected, and flower morphology and physiological activity was determined. Of each population, the number of plants using Braun-Blanquet squares was determined. The frequency and indication values showed that the two subspecies are adapted to different pH values. A. v. ssp. vallesiaca and A. v. ssp. vulneraria are clearly well separated by the red striped keel, the flag dimension, and flower size. In areas where the two species overlap, introgression occurs. The hybrid population consisted of yellow hybrid plants with red keel, yellow plants, and white plants with a red keel. The hybrids are present at a pH value between the ones of the two subspecies. The rapid increase in chlorophyll fluorescence also clearly showed that the two subspecies differed in their kinetics. The values of the hybrid plants (yellow with red keel) were between those of the populations of the two subspecies.

Jennifer E. Helm, Elizabeth G. Simpson, Lorelle I. Berkeley et al.

Abstract Understanding how vegetation management affects animals' habitat selection patterns is critical for comprehensive conservation planning. As part of a decade‐long study (2011–2019) of 486 adult female sage‐grouse in central Montana, we investigated how a conservation‐based grazing program (CGP) affected greater sage‐grouse (Centrocercus urophasianus) habitat selection at two temporal scales: (a) the seasonal scale (four biologically relevant seasons) and (b) the annual scale. We used resource selection functions to assess sage‐grouse selection for pastures enrolled in a CGP as well as plant functional type and topography. We found that sage‐grouse strongly selected shrub cover, flatter slopes, and less tree cover. They selected CGP‐enrolled pastures (Pre‐, During‐, and Post‐grazing system implementation) over Non‐CGP pastures during all seasons except the summer–fall. During the summer–fall, they selected pastures where CGP implementation was complete. Future research is needed to determine whether selection for CGP‐enrolled pastures was due to unmeasured, underlying differences between CGP and non‐CGP pastures or CGP enrollment patterns rather than effects of different grazing systems, as well as whether these habitat selection differences are linked to demographic rates or population dynamics.

T. Young

Jong Bin Kim

Yongheng Xie, Jianwen Su, Mankai Yang et al.

Abstract Prenatal dexamethasone exposure (PDE) has long-term consequences in bone development, though the underlying mechanisms remain unclear. Our results show that PDE offspring exhibit reduced bone mass, fewer osteoblasts and diminished osteoprogenitors proliferation. Further analyses show that PDE increases MKP-1 expression, while decreasing H3 lysine 9 dimethylation (H3K9me2) and H3 lysine 27 trimethylation (H3K27me3) at the Mkp-1 gene locus. Mechanistically, dexamethasone suppresses osteoprogenitors proliferation by upregulating MKP-1 expression, notably through the inhibition of H3K9me2 and H3K27me3 modifications, which promote demethylation and transcriptional activation of the Mkp-1 gene. Importantly, restoring histone methylation balance with PFI-90 or GSK-J4 treatment blocks the inhibitory effects of PDE on MAPK signaling in osteoprogenitors, and mitigates the detrimental impact of PDE on osteoprogenitor proliferation and bone development in the offspring. This study provides new insights into the epigenetic mechanism by which PDE disrupts long-term programming of fetal osteoprogenitor proliferation, ultimately impairing long bone growth in offspring.

W. Kühlbrandt

G. A. Carvalho, P. A. M. Lima, M. A. Carvalho et al.

Abstract Ateleia glazioveana Baill. is a pioneer, rustic and can be used for forest recovery. This work aimed to study the process of physiological maturation of this species. The research was carried out in the city of Alegre - ES, the trees were identified in the floral anthesis and accompanied during the filling of the fruits and development of the seeds until the complete maturation. The fruits were harvested at the following stages 7, 14, 21, 28, 35 and 42 days after anthesis, and characterized according to: morphometry, moisture, fresh and dry mass of fruits and seeds, germination, germination speed index, shoot and root length and dry mass of seedlings. The regression equations were adjusted for the main characteristics analyzed as a function of the harvest period. The point of physiological maturity of timbó occurred at 42 days after anthesis.