Reliable and Efficient Multi-rate Aware Routing Protocols for IEEE 802.11 Based MANETs

Khalid, Ahmed POSTECH Graduate School 2015 국내석사

Most existing mobile ad hoc network (MANET) routing protocols use the minimum number of hops as a routing metric. These paths tend to contain long range links that may lower both throughput and reliability. Higher throughput can be achieved by using short but effective links. A few protocols have been proposed to address this issue. The main problem with these protocols is that they use receiver signal strength indicator (RSSI) value to assess the link states. In realistic networks, RSSI value is not always accurate and hence using it can result in inaccurate decisions which will degrade the reliability of paths. Some other unaddressed issues in these protocols include: overhead of periodic hello messages, overhead of relaying data, neglecting paths with same throughput but lesser hops and neglecting changes in link states other than link breakage. We propose two reliable and efficient multi-rate aware routing protocols for MANETs: reliable and efficient multi rate aware proactive (REMAP) routing protocol and reliable and efficient multi rate aware reactive (REMAR) routing protocol. REMAP is a proactive protocol which provides a solution to the other proactive protocols. REMAR is a reactive routing protocol and it solves the problems in other traditional and multi rate aware reactive routing protocols. Both the proposed protocols do not make routing decisions based on RSSI value and hence provide more reliable paths. They also decrease the overhead caused by periodic hello messages in discovering link states of the neighbors and the overhead caused by relaying data. REMAP and REMAR ensure that the path chosen by a node is the fastest path and they update the path whenever a change in link state results in another path being faster than the current one. Simulation results show that our proposed protocols can significantly increase the path reliability and throughput and decrease the network delay and overhead.

Development of enabling technologies, production of carbonic anhydrase in plants and its immobilization to cellulose, for biocatalyst-based CO2 reduction from industrial flue gas

Razzak, Md Abdur Graduate School of POSTECH 2020 국내박사

Carbonic anhydrases (CA, EC 4.2.2.1) are Zn-containing metalloenzymes that catalyze the reversible hydration of CO2. Red alga, Gracilariopsis chorda, contain seven carbonic anhydrases (CA) that grouped into 3 main classes of CA; α-, β- and γ. These enzymes are present in all living organisms including algae and plants and play roles in various cellular processes, like photosynthesis. In this study, we characterized seven CA genes (GcCAs) from the genome sequence of the red alga Gracilariopsis chorda and analyzed them at the molecular, cellular and biochemical levels. Based on sequence data analysis, these seven isoforms categorized into four α-class, one β-class, and two γ-class isoforms. RNA sequencing data revealed that of the seven CAs isoforms, six genes well expressed in G. chorda under light at room temperature. In silico analysis also revealed that, these seven isoforms localized to multiple subcellular localizations such as the ER, mitochondria and cytoplasm. GFP fused CAs isoforms expressed in protoplasts of Arabidopsis thaliana leaf cells, and showed multiple localization patterns. The four α-class GcCAs with an N-terminal hydrophobic leader sequence localized to the ER and two of them were further trafficked to the vacuole. GcCAβ1 with no noticeable signal sequence localized to the cytosol. In spite of having a predicted presequence, the two γ-class GcCAs also localized to the cytosol. Based on these results, we propose that the red alga G. chorda also employs multiple CA isoforms for various cellular processes such as photosynthesis. Recently, CAs have gained a great deal of attention as biocatalysts for capturing CO2 from industrial flue gases owing to their extremely fast reaction rates and simple reaction mechanism. However, their general application for this purpose requires improvements to stability at high temperature and under in vitro conditions, and reductions in production and scale-up costs. In the present study, we developed a strategy for producing GcCAα3, a CA isoform from the red alga Gracilariopsis chorda, in Nicotiana benthamiana. To achieve high-level expression and facile purification of GcCAα3, we designed various constructs by incorporating of a translation-enhancing M domain and cellulose-binding domain CBM3. Of these constructs, MC-GcCAα3 was expressed at high levels in N. benthamiana via agroinfiltration with a yield of 1.0 g/kg fresh weight leaf. The recombinant protein was targeted to the endoplasmic reticulum (ER) for high-level accumulation in plants. Specific and tight CBM3-mediated binding of recombinant GcCAα3 proteins to microcrystalline cellulose beads served as a means for both protein purification from total plant extracts and protein immobilization to a solid surface for increased stability, facilitating multiple rounds of use in CO2 hydration reactions. Collectively all results demonstrate that GcCAα3 is a promising biocatalyst for CO2 capture from industrial flue gas. 탄산 탈수 효소 (CA, EC 4.2.2.1)는 CO2의 가역적 수화를 촉매하는 Zn 함유 메탈로 효소입니다. 홍조류 (Gracilariopsis chorda)는 3 가지 주요 부류의 CA로 분류 된 7 개의 탄산 탈수 효소 (CA)를 함유하고; α-, β- 및 γ. 이 효소는 조류와 식물을 포함한 모든 살아있는 유기체에 존재하며 광합성과 같은 다양한 세포 과정에서 역할을합니다. 이 연구에서 우리는 붉은 조류 Gracilariopsis chorda의 게놈 시퀀스에서 7 개의 CA 유전자 (GcCAs)를 특성화 하 고 분자, 세포 및 생 화 확적인 수준에서 분석. 서열 데이터 분석에 기초하여,이 7 개의 이소 형은 4 개의 α- 클래스, 1 개의 β- 클래스 및 2 개의 γ- 클래스 이소 형으로 분류된다. RNA 시퀀싱 데이터는 7 개의 CA 이소 형, 6 개의 유전자가 실온에서 빛 하에서 G. chorda에서 잘 발현되었음을 나타내었다. 실리코 분석에서, 이들 7 개의 이소 형은 ER, 미토콘드리아 및 세포질과 같은 다수의 세포 내 위치에 국한되는 것으로 밝혀졌다. GFP 융합 된 CA 이소 형은 아라비돕시스 탈리아 나 잎 세포의 원형질체에서 발현되었고, 다수의 국소화 패턴을 보여 주었다. N- 말단 소수성 리더 서열을 갖는 4 개의 α- 클래스 GcCA는 ER에 국한되었고, 이들 중 2 개는 액포로 추가로 트래 피킹되었다. 눈에 띄는 신호 서열이없는 GcCAβ1은 시토 졸에 국한되어 있습니다. 예측 된 서열이 있음에도 불구하고, 2 개의 γ- 클래스 GcCA는 또한 시토 졸에 국한되었다. 이러한 결과를 바탕으로, 우리는 홍조류 G. chorda가 광합성과 같은 다양한 세포 과정에 대해 다수의 CA 이소 형을 사용함을 제안한다. 최근 CA는 매우 빠른 반응 속도와 간단한 반응 메커니즘으로 인해 산업용 연도 가스로부터 CO2를 포집하는 바이오 촉매로서 많은 관심을 받고 있습니다. 그러나, 이러한 목적을위한 그들의 일반적인 적용은 고온 및 시험 관내 조건 하에서 안정성의 개선 및 생산 및 스케일 업 비용의 감소를 요구한다. 현재의 연구에서 우리는 Nicotiana benthamiana에서 붉은 조류 Gracilariopsis chorda에서 CA isoform GcCAα3 생산을위한 전략을 개발했습니다. GcCAα3의 높은 수준의 발현 및 용이 한 정제를 달성하기 위해, 본 발명자들은 번역-강화 M 도메인 및 셀룰로오스-결합 도메인 CBM3을 통합함으로써 다양한 작 제물을 설계 하였다. 이들 작 제물 중에서, MC-GcCAα3는 1.0 g / kg 신선한 중량 잎의 수율로 농밀 여과를 통해 N. 벤타 미아 나에서 높은 수준으로 발현되었다. 재조합 단백질은 식물에서 고수준 축적을 위해 소포체 (ER)를 목표로 하였다. 재조합 GcCAα3 단백질의 미세 결정질 셀룰로스 비드에 대한 특이적이고 단단한 CBM3- 매개 결합은 전체 식물 추출물로부터 단백질 정제 및 고체 표면에 대한 단백질 고정화를위한 수단으로서 작용하여 안정성을 높이고, CO2 수화 반응에서 다수의 사용을 용이하게한다. 총체적으로 모든 결과는 GcCAα3가 산업 연도 가스로부터의 CO2 포집을위한 유망한 바이오 촉매임을 입증한다.

Investigating the role of transcription factor Foxp1 in Treg mediated immune homeostasis

Ghosh, Sayantani POSTECH General Graduate School 2019 국내박사

In addition to thymus-derived tTreg cells, a second subset of peripherally induced T regulatory cells that are suggested to have evolved first in eutherian mammals to reinforce fetomaternal tolerance, eventually became instrumental in marshaling proficient immune protection to non-self-antigens continuously encountered by individuals. In contrast to the nTreg cells which develop in the highly controlled microenvironment of thymus, the pTreg cells develop in very heterogeneous condition preferentially upon TCR stimulation and TGFß mediated conversion of naïve CD4+Foxp3- T-cells. It is therefore very likely that different sets of transcription factors are instrumental in these two subsets. In search for those molecules we find Foxp1, another Foxp family protein, by being readily associated with the Foxp3 locus in a TGFβ dependent manner, is critically required during multiple phases of iTreg development and maturity. By employing an inducible model of temporal deletion of Foxp1 in precursor CD4+ T-cells, we showed that it is required for optimum expression of Foxp3 during the onset of iTreg induction. More strikingly, even a conditional ablation of Foxp1 from iTreg cells at a later developmental time point, when high level transcription of Foxp3 was already established, resulted in dramatic instability of the differentiated cell state. Consequently, mice harboring Treg specific deletion of Foxp1 displayed severely reduced iTreg compartment in lymphoid organs as well as gut associated mucosal sites, which contributed to unprovoked mucosa associated phenotypic consequence at an older age and in an experimental model of colitis induction. In summary, our results demonstrate Foxp1 as a cardinal mediator of the iTreg differentiation process. We propose that such non-redundant requirement of an evolutionarily related sibling of a key lineage determining factor may represent a general principle to ensure stability in cellular differentiation processes. Finally, provided Treg cells are widely pursued as an option for adoptive transfer mediated cellular therapy, our findings posit therapeutic implications by conferring long term stability of in vitro expanded patient derived iTreg cells in clinical settings.