Araneus ventricosus

Araneus ventricosus is able to produce flagelliform silk, also known as dragline silk, which has been found to be the most elastic of all spider silk types.^[10] However, this highly valuable silk type is very difficult to create through artificial means.^[11] Since spider silk has a variety of potential uses, including in fabrics and biomedical technologies, the sequence motifs for genes coding for this silk in the species have been studied to examine the potential for artificial production. In the study by Lee et al., clones of the genes for this silk were produced and injected into insect cells to determine if future cells would also contain these genetic motifs. Since the later generations of this strain of cells were able to maintain the AvFlag tag, it was discovered that the species could potentially be used to produce large quantities of this dragline spider silk.^[10]

The spidroins that make up all types of spider silk are produced by glands. In orb-weaving spiders, like Araneus ventricosus, there are typically seven or fewer of these glands. The silk proteins created by the glands include flagelliform spidroins, called Flag; tubuliform spidroins, called TuSp; aciniform spidroins, called AcSp; aggregate spidroins, called AgSp; pyriform spidroins, called PySp; and major and minor ampullate spidroins, respectively called MaSp and MiSp. Of these proteins, AcSp and TuSp help to create egg coverings, while the other five are involved in the spider silk's structure. However, thanks to recent analysis of the Araneus ventricosus genome, it has been discovered that there may be more than these seven spidroin types.^[12] Tubuliform silk, which may also be called cylindriform silk, is used to develop egg coverings, so it is only produced by glands in female spiders. One specific tubuliform spidroin gene in Araneus ventricosus, TuSp1, has been studied using a long distance polymerase chain reaction. Through this study, it was found that 1921 amino acid residues with 9 collective repeats can be coded for by the gene's main component.^[5]

Aciniform silk, on the other hand, is involved in prey-wrapping behaviors along with creating egg coverings. With these two uses, this form of spider silk is much stronger and more flexible than most other silk types, making it a valuable research subject. For instance, similarly to the TuSp1 gene, a long distance PCR was performed on the gene for the aciniform spidroins in Araneus ventricosus, AcSp1. This procedure found that AcSp1 produces a protein with 3445 amino acids and contains 10338 base pairs.^[6]

Orb-weavers' anterior median eyes have three types of eye cells - blue, ultraviolet, and green. In noct-diurnal spiders, meaning those active during both the day and night, the blue eye cells have been found to be most responsive to circadian systems. In the nocturnal Araneus ventricosus, it has then been found that their anterior median eyes are able to change sensitivity in accordance with their circadian rhythm, meaning that the spider likely has an efferent optic nerve. Additionally, their eyes are unable to find differences in color and have only one type of photoreceptor.^[7]

The central nervous system of Araneus ventricosus contains fused supraesophageal ganglia, which are then composed of substantially-sized clusters of neurons. These supraesophageal ganglia eventually lead to the spider's four pairs of eyes through the optic nerve. The leading portion of the nerve cord then consists of the subesophageal ganglia, including the ventral subesophageal mass. The subesophageal ganglia, unlike the supraesophageal ganglia, are responsible for the nerves tied to the spider's appendages and pedipalps. Furthermore, the Araneus ventricosus subesophageal mass and brain both lack soma, or cell bodies, in the neurons of their central fibrous masses.^[14]