Genome-wide CRISPR Screens Reveal Host Factors Critical for SARS-CoV-2 Infection

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ADAPTATIONS TO CLIFF-NESTING IN SOME ARCTIC GULLS (LARUS)

Various aspects of the breeding of three gulls, Larus thayeri, glaucoides and hyperboreus, which nested in colonies both on cliff ledges and on level ground in the eastern Canadian Arctic, were compared with those of the ground-nesting L. argentatus and the cliff-nesting Rissa tridactyla. As the result of adaptation to cliff ledge nesting, many aspects of the breeding biology of R. tridactyla were strikingly different from those of the ground-nesting European L. argentatus, but the behaviour of L. thayeri, glaucoides and hyperboreus clearly spanned these differences. Cliff-nesting individuals of thayeri and glaucoides were most like Rissa; ground-nesting individuals of these species were most like argentatus. L. thayeri was more like Rissa than was glaucoides. With but few exceptions, both cliff- and ground-nesting individuals of hyperboreus were most like argentatus. The factors responsible for the intra-specific differences between cliff- and ground-nesters of thayeri and glaucoides are not clear. Limited gene exchange between cliff and ground colonies occurs. Because of physical features of the nest, first-laid eggs were more liable to fall from ledges than second or third eggs. L. thayeri and glaucoides have evolved separate mechanisms to cope with this problem. Egg shape was multimodal in thayeri and glaucoides. Long pyriform eggs were less liable to fall from ledges than eggs of other shapes. L. thayeri laid more long pyriform eggs as first eggs than did glaucoides. L. thayeri lost fewer eggs than did glaucoides, but glaucoides replaced all lost eggs while thayeri did not. Delayed follicular atresia provided glaucoides with insurance of egg replacement. In thayeri, accessory follicles were reabsorbed after the first egg was laid; in argentatus, after the second egg, and in glaucoides after the third egg. At the approach of a predator, it was advantageous for cliff-dwelling chicks to remain motionless but for ground-dwelling chicks to flee their nests and to hide. Among the cliff-nesters, the “freezing in place” reaction of chicks was best developed in thayeri, to a lesser extent in glaucoides, and least in hyperboreus. Among the ground-nesters, chicks of glaucoides and hyperboreus behaved like those of argentatus and fled their nests when disturbed, but chicks of thayeri froze like their cliff-dwelling siblings. Reciprocal transfers of eggs and chicks between cliff and ground colonies indicated that in argentatus, glaucoides and hyperboreus, the factors determining a chick's reaction to disturbance came into play between hatching and the eighth day. In thayeri, the reaction appeared to be effectively innate. Chicks of glaucoides showed a greater predisposition to this behaviour than chicks of argentatus after both had received identical experience on cliff ledges. In thayeri, stereotypy of the freezing reaction has probably been a factor limiting the colonisation of areas where cliffs are scarce but predators present. In argentatus, lack of perfection of this behaviour (compared to glaucoides and thayeri) has probably been a factor preventing argentatus from attaining cliff ledges. L. hyperboreus, although nowhere abundant, is a widespread species nesting on level ground and on cliff ledges but lacking the modifications observed in glaucoides and thayeri; this is due to its size and aggressiveness, the fact that it picks nest-sites before glaucoides and thayeri arrive in the colonies, and that on cliffs it chooses the largest and most level ledges.     

DNA sequence homology between attB-related sites of Corynebacterium diphtheriae, Corynebacterium ulcerans, Corynebacterium glutamicum, and the attP side of γ-Cornephage

Chromosomal restriction fragments of Corynebacterium ulcerans and C. diphtheriae, containing an integration site for corynephages of the beta family, show homology on Southern blots. Homologous DNA in also found in the soil isolate C. glutamicum, although this strain is not susceptible to beta-corynephages. Three of these DNA fragments, one for each bacterial strain, and a fragment of gamma-corynephage DNA previously shown to contain the phage integration site, were cloned and sequenced. Alignment of the 3 bacterial sequences shows a very high degree of homology in a stretch of ca 120 nucleotides, whereas the rest of the sequences is generally non-homologous. Within this common bacterial portion, a segment of ca. 96 nucleotides (core sequence) is also highly homologous to the phage sequence. The first half (ca. 50 bp) of the core sequence is identical in all aligned sequences whereas the second half, which is largely occupied by a stem-and-loop structure, contains point mutations peculiar to each clone. The described sequences are likely to be involved in phage integration/excision processes.     

The association between spontaneous pyelonephritis and maturity-onset diabetes mellitus in male MM mice

Blood glucose and glucose tolerance tests demonstrated that many male MM mice are diabetic. Serial urine sampling showed that the diabetes occurred only in mature MM males and consisted of a single self-limiting episode. Histological examination of the pancreas, together with measurements of body weight, glycosylated haemoglobin and plasma insulin, revealed that the diabetes was of the maturity-onset insulin-resistant type. Bacteriological examination of the urine samples showed that urinary tract infection, a known feature of male MM mice, occurred in the diabetics but only after the onset of hyperglucosuria. It was concluded that the high urinary glucose levels of diabetic MM males are of prime importance in the aetiology of the renal infection which occurs rarely in non-diabetic MM males or in other strains in the colony. An infectious aetiology for the diabetes per se was excluded by the existence of diabetes in germfree MM males.     

Characterization of murine monoclonal antibodies to human interferon-gamma (IFN-gamma) and their application for sandwich enzyme-linked immunosorbent assay (ELISA)

The three murine monoclonal antibodies (MAb), D1G2, D9D10, and D13C8, are specific for human interferon-gamma (IFN-gamma), but not human IFN-alpha and IFN-beta. They react weakly with heat-treated IFN-gamma. The three antibodies recognize different epitopes of the IFN-gamma molecule, as evaluated by antibody-binding inhibition experiments. We have used these three monoclonal antibodies to construct a sandwich enzyme-linked immunosorbent assay (ELISA). The best result was obtained when we used D1G2 or D9D10 MAb as a solid-phase immunosorbent and D1G2 or D9D10 MAb as a tracer. When we measured IFN-gamma in sera by a combination of D1G2 (a solid-phase) and D1G2 (a tracer), a result similar to the one by a combination of D9D10 (a solid-phase) and D1G2 (a tracer), was obtained. This may suggest that human IFN-gamma exists in oligomeric form. Recombinant human IFN-gamma expressed in E. coli is detectable at a concentration of 1 ng/ml in this sandwich ELISA. This assay can be employed for the analysis of the structural characteristics of the human IFN-gamma molecule as well as measurement of IFN-gamma in human sera and tissue culture fluids.     

Taxonomic studies ofAsarum sensu lato

The floral vascular anatomy of 12 species representing each ofAsarum s. str.,Asiasarum, Geotaenium, Heterotropa andHexastylis are compared to clarify intergeneric relationships. The five genera have basically similar structures in floral morphology and vasculature, and consistently have a six-carpelled compound ovary and the associated similar placental vasculature. They show, however, a significant difference in the position and the constituent of the “ventral” carpellary bundles in the placental axis betweenAsiasarum-Heterotropa-Hexastylis andAsarum-Geotaenium. InAsiasarum, Heterotropa andHexastylis the ventral bundles of each carpel are basically free and antilocular as expected in the least specialized compound ovary of angiosperms; in contrast, inAsarum andGeotaenium the ventral carpellary bundles are antiseptal and heterogenous (i.e., formed by the lateral fusion of ventral bundles of adjacent carpels). Shared probable apomorphic floral vasculature, as well as shared single style-column, suggests the closest mutual relationships betweenAsarum andGeotaenium. In terms of floral morphology and anatomy,Asiasarum, Heterotropa andHexastylis retain plesiomorphies. Possible chromosomal evolution in the related genera is also discussed.     

Simultaneous measurement of atrial natriuretic polypeptide (ANP) messenger RNA and ANP in rat heart--evidence for a preferentially increased synthesis and secretion of ANP in left atrium of spontaneously hypertensive rats (SHR)

Tissue levels of atrial natriuretic polypeptide (ANP) messenger RNA (ANPmRNA) and ANP in the rat heart were measured simultaneously. In Wistar rats, ANPmRNA of the same size (approximately 0.95 kbp) was detected in all four chambers of the rat heart. The ANPmRNA level was the highest in the right atrium, and the left atrial level was slightly lower than the right atrial level. Ventricular levels were more than two orders of magnitude lower than atrial levels. Tissue ANP concentrations of four chambers were roughly parallel to ANPmRNA levels. In spontaneously hypertensive rats (SHR) with the elevated plasma ANP level, the ANPmRNA level in the left atrium was substantially increased. The left/right ratio of atrial ANPmRNA level in SHR (150%) was higher than that in control Wistar Kyoto rats (WKY) (90%). In contrast, the left/right ratio of atrial ANP concentration was decreased in SHR (44%) compared with that in WKY (84%). The ratio of ANP to ANPmRNA levels in the left atrium of SHR was about three times smaller than that in the right atrium of SHR, and those in bilateral atria of WKY. These results indicate that the biosynthesis and secretion of ANP from the left atrium is preferentially increased in SHR. Thus, simultaneous determination of ANPmRNA and ANP levels is a refined strategy of investigation for the biosynthesis, storage and secretion of ANP.