Relation between the outer cover of the egg case of Argiope aurantia (Araneae: Araneidae) and the emergence of its spiderlings

Abstract

To emerge from the egg case, Argiope aurantia spiderlings must penetrate a tightly woven outer cover composed primarily of large-diameter cylindrical gland fibers and small-diameter fibers, likely of aciniform gland origin. They accomplish this using enzymatic digestion and mastication to form a communal hole in the outer cover. The involvement of proteolytic enzymes in this process was demonstrated by zymography of spiderling homogenates and washes made from the edges of holes. The specific source(s) of the proteases is unknown, but histological examination of spiderling sections indicates that the digestive tract, venom glands, and gnathocoxal glands are all functioning at the time of emergence from the egg case. Observations on edges of holes indicate that spiderlings are able to solubilize the small-diameter fibers completely, but cylindrical gland fibers only partially. In the outer cover, cylindrical fibers are composed of numerous fibrils embedded within a matrix. Spiderlings appear to be unable to solubilize the fibrils, but digestion of the matrix allows the spiderlings to push the fibrils aside to create the opening.

Modular evolution of egg case silk genes across orb-weaving spider superfamilies

“…tubuliform glands were largely composed of alanine (26%) and serine (22%) ( Table 1). These compositions closely matched those reported for tubuliform glands (16) and egg case silk fibers (11,17) of other araneoid spiders. Moreover, the predicted amino acid compositions of the A.ar.…”

“…Spiders construct egg cases, protective cocoons where eggs undergo development, primarily from silk fibers synthesized by the tubuliform (cylindrical) silk glands, and tubuliform fibers are exclusively used for egg case construction (6,11). Tubuliform glands are found only in female spiders, and silk synthesis is initiated in these glands at sexual maturation (6,12).…”

“…Recently, Hu et al (15) reported another putative component of egg case silk (ECP-1) expressed in silk glands of the black widow spider, Latrodectus hesperus. However, the translated sequence of neither ADF-2 nor ECP-1 could account for the amino acid composition of tubuliform silk fibers or the gland's contents (4,11,15,16,17), indicating that the dominant silk expressed by tubuliform glands must be a different, unidentified protein (4).…”

Astacin family metallopeptidases and serine peptidase inhibitors in spider digestive fluid

“…For some orb-weavers, including the araneid Argiope aurantia Lucas 1833, peptidases also play a role in the emergence of young spiders from the egg sac (Foradori et al 2002). The study of spider digestive enzymes spans more than a century (early studies reviewed in Pickford 1942), but has been sporadic and remains a largely unexplored area.…”

Histologic and Microstructural Analyses on Postembryonic Development in the Wolf Spider Arctosa kwangreungensis (Araneae: Lycosidae)

“…이들 신 경절로부터 수많은 신경들이 분지되어 몸 전체에 말초신경 계를 구성하고 있다. 대부분의 신경들은 거미의 다양한 근 육조직이나 감각기와 연결되어 있으므로 (Babu, 1985;Weygoldt, 1985), 발생 초기의 신경분화는 보행과 관련된 부속지 나 시각과 관련된 시각기 등의 신경발달과 밀접한 연관을 지니고 있을 것으로 추정된다 (Babu, 1975;Hwang & Moon, 2003 (Foradori et al, 2002). …”