There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

https://biblio.ugent.be/publication/685594/file/1130605.pdf

Review of Particle Physics

Optical coherence tomography (OCT) has developed rapidly since its first realisation in medicine and is currently an emerging technology in the diagnosis of skin disease. OCT is an interferometric technique that detects reflected and backscattered light from tissue and is often described as the optical analogue to ultrasound. The inherent safety of the technology allows for in vivo use of OCT in patients. The main strength of OCT is the depth resolution. In dermatology, most OCT research has turned on non-melanoma skin cancer (NMSC) and non-invasive monitoring of morphological changes in a number of skin diseases based on pattern recognition, and studies have found good agreement between OCT images and histopathological architecture. OCT has shown high accuracy in distinguishing lesions from normal skin, which is of great importance in identifying tumour borders or residual neoplastic tissue after therapy. The OCT images provide an advantageous combination of resolution and penetration depth, but specific studies of diagnostic sensitivity and specificity in dermatology are sparse. In order to improve OCT image quality and expand the potential of OCT, technical developments are necessary. It is suggested that the technology will be of particular interest to the routine follow-up of patients undergoing non-invasive therapy of malignant or premalignant keratinocyte tumours. It is speculated that the continued technological development can propel the method to a greater level of dermatological use.

https://link.springer.com/content/pdf/bfm%3A978-3-319-06419-2%2F1.pdf

Optical Coherence Tomography

Structural Equations with Latent Variables.

Organogenesis in plants occurs at the shoot apical meristem, a group of indeterminate stem cells that are organized during embryogenesis. Regulated initiation of leaves or flowers from the shoot meristem gives rise to the familiar geometric patterns observed throughout the plant kingdom. The mechanism by which these patterns, termed phyllotaxies, are generated, remains unclear. Maize plants initiate leaves singly, alternating from one side to the other in a regular pattern. Here we describe a recessive maize mutant, abphyl1, that initiates leaves in opposite pairs, in a pattern termed decussate phyllotaxy. The decussate shoot meristems are larger than normal throughout development, though the general structure and organization of the meristem is not altered. abph1 mutants are first distinguished during embryogenesis, prior to true leaf initiation, by a larger shoot meristem and coincident larger expression domain of the homeobox gene knotted1. Therefore, the abph1 gene regulates morphogenesis in the embryo, and plays a role in determining the phyllotaxy of the shoot.

Control of phyllotaxy in maize by the abphyl1 gene.

Tissue inflammation induces rapid mobilization of antigen-charged dendritic cells (DCs), which migrate to draining lymph nodes via afferent lymphatics to elicit the immune response. This increase in DC trafficking has been shown to require integrin-dependent adhesion to ICAM-1 and VCAM-1, expressed on inflamed lymphatic endothelium. In addition, both constitutive- and inflammation-induced DC migration involves the chemokine CCL21, which most likely triggers integrin activation on DC via its receptor CCR7. Recently, however, conflicting evidence has suggested that DC entry occurs independently of integrins, implying that the role of CCL21 in lymphatics is purely chemotactic. Hence, while CCL21 is reported to be inducible during inflammation, the details of this induction and the role of CCL21 during initial DC trafficking are unclear. Here, we have characterized both the production of CCL21 and the mechanism of its action in DC transmigration using primary human dermal lymphatic endothelial cells (HDLECs) and a mouse model of skin contact hypersensitivity. We showed that CCL21 is constitutively expressed intracellularly but rapidly secreted after exposure to the inflammatory cytokine tumour necrosis factor (TNF) α following de novo RNA and protein synthesis. Furthermore, using in vitro transmigration assays, we showed that endogenous HDLEC-derived CCL21 stimulates DC translymphatic migration by a predominantly chemotactic mechanism in resting HDLEC and by a β2 integrin-mediated mechanism in TNFα-stimulated HDLEC. These results imply a direct role for CCL21 in lymphatic transmigration that involves the selective use of integrin activation in inflammation.

Inflammation-induced secretion of CCL21 in lymphatic endothelium is a key regulator of integrin-mediated dendritic cell transmigration

http://www.jbc.org/content/282/46/33671.full.pdf

Inflammation-induced uptake and degradation of the lymphatic endothelial hyaluronan receptor LYVE-1.

Cell-to-cell communication in plants includes the selective trafficking of transcription factors and other signals through plasmodesmata. The KNOTTED1 (KN1) homeobox (KNOX) family transcription factors, which use this pathway, are essential for stem cell establishment and/or maintenance. Here we show that KN1 trafficking requires the chaperonin complex, which belongs to a group of cytosolic chaperones that fold specific substrate proteins. Genetic and physical interaction data show a functional relevance for chaperonins in KNOX family-dependent stem cell maintenance. Furthermore, tissue-specific complementation assays indicate a mechanistic basis for chaperonin function during the posttranslocational refolding process. Our study shows that chaperonins are essential for the cell-to-cell trafficking of a subset of mobile transcription factors and demonstrates the importance of chaperonin-dependent protein trafficking for plant stem cell function.

https://science.sciencemag.org/content/sci/333/6046/1141.full.pdf

Chaperonins Facilitate KNOTTED1 Cell-to-Cell Trafficking and Stem Cell Function

We have recently shown that cellular RNA is synthesized at a sub-nuclear structure, the nuclear cage1, which contains proteins also found in other structures called variously the nuclear pore complex, lamina, envelope and matrix2–6. Is the RNA of an exogenous virus also synthesized at the cage? We chose to study influenza virus as it is unusual in its requirement for a host cell nucleus even though there are no cellular counterparts to the transcription of the infecting negative strands of genomic influenza RNA, nor to the replication of the resulting positive RNA strands to form new virion RNA. The cellular sites of these processes have not yet been definitively demonstrated7,8. We now show that nascent viral transcripts are closely associated with the cage and we conclude not only that transcription and replication of viral RNA are nuclear, but also that they occur at fixed sites in the nucleus.

David A. Jackson

Papers

Control of phyllotaxy in maize by the abphyl1 gene.

Inflammation-induced secretion of CCL21 in lymphatic endothelium is a key regulator of integrin-mediated dendritic cell transmigration

Inflammation-induced uptake and degradation of the lymphatic endothelial hyaluronan receptor LYVE-1.

Chaperonins Facilitate KNOTTED1 Cell-to-Cell Trafficking and Stem Cell Function

Influenza virus RNA is synthesized at fixed sites in the nucleus