The common house spider, Parasteatoda tepidariorum, maintains silk gene expression on sub-optimal diet

Abstract

Cobweb weaving spiders and their relatives spin multiple task-specific fiber types. The unique material properties of each silk type result from differences in amino acid sequence and structure of their component proteins, primarily spidroins (spider fibrous proteins). Amino acid content and gene expression measurements of spider silks suggest some spiders change expression patterns of individual protein components in response to environmental cues. We quantified mRNA abundance of three spidroin encoding genes involved in prey capture in the common house spider, Parasteatoda tepidariorum (Theridiidae), fed different diets. After 10 days of acclimation to the lab on a diet of mealworms, spiders were split into three groups: (1) individuals were immediately dissected, (2) spiders were fed high-energy crickets, or (3) spiders were fed low-energy flies, for 1 month. All spiders gained mass during the acclimation period and cricket-fed spiders continued to gain mass, while fly-fed spiders either maintained or lost mass. Using quantitative PCR, we found no significant differences in the absolute or relative abundance of dragline gene transcripts, major ampullate spidroin 1 (MaSp1) and major ampullate spidroin 2 (MaSp2), among groups. In contrast, prey-wrapping minor ampullate spidroin (MiSp) gene transcripts were significantly less abundant in fly-fed than lab-acclimated spiders. However, when measured relative to Actin, cricket-fed spiders showed the lowest expression of MiSp. Our results suggest that house spiders are able to maintain silk production, even in the face of a low-quality diet.

SARS-CoV-2 infection hospitalization, severity, criticality, and fatality rates in Qatar

“…The infection fatality rate in Italy was found to be tenfold higher than that in Qatar, only because of the population’s different age structure. These findings indicate that the infection morbidity and mortality may vary immensely across countries, and will be substantially lower in countries with younger demographic structures, as suggested earlier 12 .…”

“…Building on our previously developed SARS-CoV-2 models 12 – 18 , an age-structured deterministic mathematical model was constructed to describe SARS-CoV-2 transmission dynamics and disease progression in the population from the epidemic onset up to November 22, 2020 (Supplementary Figure S2 ). Susceptible individuals in each age group were at risk of acquiring the infection based on their infectious contact rate per day, age-specific susceptibility to the infection, and an age-mixing matrix defining mixing between individuals in the different age groups.…”

Characterizing the Qatar advanced-phase SARS-CoV-2 epidemic

“…Not only were serious disease and mortality very strongly linked to being > 50 years of age, but most infections in younger persons exhibited no or minimal/mild symptoms. Age may have even played a role in the risk of exposure or susceptibility to the infection (Table 5 ), as suggested earlier 44 , 45 . These findings may suggest that the epidemic expansion in nations with young populations may lead to milder disease burden than previously thought.…”

Basic Principles in the Design of Spider Silk Fibers

“…Although it is assumed that this variability may represent an evolutionary advantage, since it allows to adapt the properties of the fiber to the immediate requirements of the spider [11], it was soon realized that this feature represented a fundamental drawback for the thorough characterization of the material. Thus, many pressing questions related with the extent of this variability remained largely unanswered [12][13][14], most importantly those related with the differences in the silks spun by different spider species [15]. This variability is illustrated in Figure 1a, where a set of representative stress-strain curves of major ampullate spider silk (MAS) fibers spun by Argiope trifasciata specimens is shown.…”