Lamellar bodies in the epithelial bronchiolar cells in the mouse

Summary Lamellar bodies are described in the non-ciliated epithelial bronchiolar cells of the normal mouse lung. They are constituted of smooth concentric membranes, with a cytoplasmic center. They are related to mitochondria. They seem to belong to smooth endoplasmic reticulum. An origin from Golgi elements is discussed. Acknowledgment. This work was supported by Grant No 69088 of Conseil de la Recherche Médicale du Québec.     

Distribution of radiolabelled monoclonal antibody Po66 after intravenous injection into nude mice bearing human lung cancer grafts

Monoclonal antibody Po66, produced by immunization against a patient's lung squamous cell carcinoma was found suitable for the scintigraphic detection of human tumours. Surprisingly, the cellular antigen recognized by Po66 was abundant in the cytoplasm of tumour cells but could not be detected on the surface membrane. In the present work the biodistribution of radiolabelled Po66 and of an unrelated immunoglobulin were studied comparatively after intravenous injection into nude mice bearing lung squamous cell carcinoma grafts. Radioactivity distribution among mouse organs and tumour was analysed by gamma counting and autohistoradiography. After injection, radiolabelled Po66 decreased rapidly from the blood in tumour-bearing animals whereas, in controls, it remained at a level comparable to that of the unrelated immunoglobulin. The antibody seemed slowly trapped by the tumour and, 12 days after its injection, distribution ratios between tumour and mouse organs reached values of 20-30 as against 1 in animals injected with the non-specific immunoglobulin. Autohistoradiographic investigations in the tumour confirmed the slow diffusion rate of the antibody, which remained in the vascular spaces up to the 24th hour after injection and diffused afterwards throughout the clusters of tumor cells. Furthermore, radioactivity was detected in cells which, unexpectedly, seemed morphologically unaltered. These cells, the viability of which remains to be determined, were predominant in the central area of the tumours. The results presented constitute new evidence of the ability of an in vivo injected monoclonal antibody to reach a cytoplasmic target inside non-necrotic cells and suggest that the cells permeable to the antibody might be in defective nutritional conditions.     

Influence of the culture conditions of brucella abortus on its antitumor properties

A heat-inactivated rough mutant of B. abortus increased resistance to a transplantable lymphoma when cultured on solid agar (ag) but not when cultured on a fluid medium (fl). The ag organisms were smaller, more toxic and induced more interferon 2 h after injection than fl. They also contained a phospholipid (cardiolipin) absent from fl preparations.     

Métabolisme du chloro-2 (p-chlorophényl)-3 propionate de méthyle et problème de sélectivité

The product of hydrolysis of the active principle of the herbicide Bidisine® is degraded in at least two different ways. One way gives p-chlorobenzoic acid. The other, more important one, gives a conjugate with l-cysteine, which is further oxidized. The ability to oxidize the conjugate provided a means of distinguishing between susceptible and resistant plant species.     

The importance of naturally attenuated SARS-CoV-2in the fight against COVID-19

The current SARS-CoV-2 pandemic is wreaking havoc throughout the world and has rapidly become a global health emergency. A central question concerning COVID-19 is why some individuals become sick and others not. Many have pointed already at variation in risk factors between individuals. However, the variable outcome of SARS-CoV-2 infections may, at least in part, be due also to differences between the viral subspecies with which individuals are infected. A more pertinent question is how we are to overcome the current pandemic. A vaccine against SARS-CoV-2 would offer significant relief, although vaccine developers have warned that design, testing and production of vaccines may take a year if not longer. Vaccines are based on a handful of different designs (i), but the earliest vaccines were based on the live, attenuated virus. As has been the case for other viruses during earlier pandemics, SARS-CoV-2 will mutate and may naturally attenuate over time (ii). What makes the current pandemic unique is that, thanks to state-of-the-art nucleic acid sequencing technologies, we can follow in detail how SARS-CoV-2 evolves while it spreads. We argue that knowledge of naturally emerging attenuated SARS-CoV-2 variants across the globe should be of key interest in our fight against the pandemic.     

Insects and incest: Sib‐mating tolerance in natural populations of a parasitoid wasp

Sib‐mating avoidance is a pervasive behaviour that is expected to evolve in species subject to inbreeding depression. Although laboratory studies provide elegant demonstrations, small‐scaled bioassays minimize the costs of mate finding and choice, and thus may produce spurious findings. We therefore combined laboratory experiments with field observations to examine the existence of inbreeding avoidance using the parasitoid wasp Venturia canescens. In the laboratory, our approach consisted of mate‐choice experiments to assess kin discrimination in population cages with competitive interactions. A higher mating probability after sib rejections suggested that females could discriminate their sibs; however, in contrast to previous findings, sib‐mating avoidance was not observed. To compare our laboratory results to field data, we captured 241 individuals from two populations. Females laid eggs in the lab, and 226 daughters were obtained. All individuals were genotyped at 18 microsatellite loci, which allowed inference of the genotype of each female's mate and subsequently the relatedness within each mating pair. We found that the observed rate of sib‐mating did not differ from the probability that sibs encountered one another at random in the field, which is consistent with an absence of sib‐mating avoidance. In addition, we detected a weak but significant male‐biased dispersal, which could reduce encounters between sibs. We also found weak fitness costs associated with sib‐mating. As such, the sex‐biased dispersal that we found is probably sufficient to mitigate these costs. These results imply that kin discrimination has probably evolved for purposes other than mate choice, such as superparasitism avoidance.     

A high-throughput media design approach for high performance mammalian fed-batch cultures

An innovative high-throughput medium development method based on media blending was successfully used to improve the performance of a Chinese hamster ovary fed-batch medium in shaking 96-deepwell plates. Starting from a proprietary chemically-defined medium, 16 formulations testing 43 of 47 components at 3 different levels were designed. Media blending was performed following a custom-made mixture design of experiments considering binary blends, resulting in 376 different blends that were tested during both cell expansion and fed-batch production phases in one single experiment. Three approaches were chosen to provide the best output of the large amount of data obtained. A simple ranking of conditions was first used as a quick approach to select new formulations with promising features. Then, prediction of the best mixes was done to maximize both growth and titer using the Design Expert software. Finally, a multivariate analysis enabled identification of individual potential critical components for further optimization. Applying this high-throughput method on a fed-batch, rather than on a simple batch, process opens new perspectives for medium and feed development that enables identification of an optimized process in a short time frame.     

Reciprocal epithelial:endothelial paracrine interactions during thyroid development govern follicular organization and C-cells differentiation

The thyroid is a highly vascularized endocrine gland, displaying a characteristic epithelial organization in closed spheres, called follicles. Here we investigate how endothelial cells are recruited into the developing thyroid and if they control glandular organization as well as thyrocytes and C-cells differentiation. We show that endothelial cells closely surround, and then invade the expanding thyroid epithelial cell mass to become closely associated with nascent polarized follicles. This close and sustained endothelial:epithelial interaction depends on epithelial production of the angiogenic factor, Vascular Endothelial Growth Factor-A (VEGF-A), as its thyroid-specific genetic inactivation reduced the endothelial cell pool of the thyroid by >90%. Vegfa KO also displayed decreased C-cells differentiation and impaired organization of the epithelial cell mass into follicles. We developed an ex vivo model of thyroid explants that faithfully mimicks bilobation of the thyroid anlagen, endothelial and C-cells invasion, folliculogenesis and differentiation. Treatment of thyroid explants at e12.5 with a VEGFR2 inhibitor ablated the endothelial pool and reproduced ex vivo folliculogenesis defects observed in conditional Vegfa KO. In the absence of any blood supply, rescue by embryonic endothelial progenitor cells restored folliculogenesis, accelerated lumen expansion and stimulated calcitonin expression by C-cells. In conclusion, our data demonstrate that, in developing mouse thyroid, epithelial production of VEGF-A is necessary for endothelial cells recruitment and expansion. In turn, endothelial cells control epithelial reorganization in follicles and C-cells differentiation.     

Synthesis of N<Subscript>ɛ</Subscript>-protected-L-lysine and γ-benzyl-L-glutamate N-carboxyanhydrides (NCA) by carbamoylation and nitrosation

Summary. This paper reports on an original process to synthesize N-carboxyanhydrides, which consists of nitrosating N-carbamoylamino acids with a NO/O₂ gas mixture in acetonitrile. The synthesis of several N-carbamoylamino acids of L-lysine was described using potassium cyanate in water. The latter were then nitrosated to yield the corresponding NCA with more or less efficiency. Indeed, the NCA carrying an acid-sensitive protecting group led to a partial deprotection to give the L-lysine NCA salt. The NCA of N-trifluoroacetyl-L-lysine, N-benzyloxycarbonyl-L-lysine and -benzyl-L-glutamate were successfully synthesized with satisfactory yields. Their polymerizability was compared to that of the N-trifluoroacetyl-L-lysine NCA initiated by n-hexylamine in N,N-dimethylformamide. It also showed that this new process of NCA synthesis could be applied to the synthesis of polypeptides and more generally to the protein chemistry.     

Analysis and characterisation of IL-1beta processing in rainbow trout, Oncorhynchus mykiss

Mammalian IL-1beta is produced as a biologically inactive 31 kDa precursor, which is converted to the active 18 kDa form by proteolytic processing. Synthesis and processing of native piscine IL-1beta is poorly understood. In the present study, the native IL-1beta precursor or mature peptides were detected at sizes of approx. 29 kDa and 24 kDa in cell lysates of a rainbow trout macrophage cell line RTS-11, with or without LPS stimulation, by Western blot analysis using a polyclonal antibody against the putative trout mature IL-1beta (rmIL-1beta) produced in Escherichia coli. Processing of the 29 kDa precursor into a 24 kDa mature peptide was confirmed by analysis of such proteins using a monoclonal conjugate (Ni-NTA-HRP) against 6 histidines in lysates of the RTS-11 cells transfected with an expression plasmid containing the IL-1beta precursor molecule tagged with 6 histidines at its C terminus. Only the recombinant mature 24 kDa) IL-1beta/HIS protein was purified from the culture supernatants of the transfected cells, indicating the molecule is cleaved to be secreted. These findings strongly suggest that the trout IL-1beta molecule is processed in trout macrophages in an analogous way to the situation with mammalian IL-1beta despite the lack of a clear ICE cut site.