Genetic mapping of chromosome 6 in tomato (Solanum lycopersicum L.) based on newly developed Short Sequence Repeat (SSR) markers

Date

2010

Degree

Bachelor of Science in Biology

Major Course

Major in Zoology

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Ayolani V. De Lara

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Abstract

The gross anatomy of the reproductive system and histology of the ovotestis of Ryssota otaheitana, the largest and most edible land snail in the Philippines, were studied. The objectives of this study are: (1) to determine the approximate size of the sexually mature snails; (2) to identify and describe the various parts of the reproductive system of snails belonging to different size classes; and (3) to describe the cellular components of the ovotestis by light and electron microscopy. Based on shell diameter, the snails were grouped into six size classes, namely: class I, 31-40 mm; class II, 41-50 mm; class III, 51-60 mm; class IV, 61-70 mm; class V, 71-80 mm; class VI, 81-90 mm. Three samples from each class were randomly selected, except for class I, with only one sample. These were dissected and the gross morphology of its reproductive system was examined. The ovotestis, together with the surrounding digestive gland, was dissected out and processed for light and electron microscopy. Results showed that all parts of the reproductive system were identifiable in snails with a shell diameter of about 73.20 mm (class V). The albumen gland belonging to class V and class VI was greatly enlarged. Class I-IV snails, although still immature, their penis was already developed. The ovotestis was biggest in class VI. It was deeply embedded in the digestive gland and only a small amount of connective tissue separated them. The organ was composed of four lobes containing numerous acini of variable size. The acinus was occupied by several clusters of spermatogenic cells and Sertoli cells. However, no secondary spermatocytes were observed. The spermatozoa have an elongated nucleus and with very long tail forming hair-like bundles when they aggregate. They exhibited the 9+2 pattern. On the other hand, only four oocytes were found in the entire section of the ovotestis. These were peripherally located in the acinus and could easily be recognized by its large size and ovoid shape. This study provides baseline information on some aspects of the snail reproductive biology that would be very helpful in the management and conservation of the said species.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Document Type

Thesis

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