Punjab University Journal of Zoology

7-18

Authors: Akhtar Tanveer

A study was made on the hemocyte morphology of freshwater snails Physa acuta and Bellamaya bengalensis. The hemolymph directly obtained from the heart was allowed to settle for 30 minutes before fixation and staining. Both snail species showed two basic types of hemocytes known as spreading hemocytes and round hemocytes. Light microscopy of these hemocytes revealed behavioural distinctions. In both the snails studied, the spreading hemocytes predominates. Mean percentage of these cells constitutes 90.51 ± 3.71 and 93.38±2.03 for P. acuta and B. bengalensis respectively. Similar values for round hemocytes were 6.62±1.22 and 9.48±1.01 percent. Majority of the spreading hemocytes were mononucleated. However, less than 2% of the total blood cells were binucleated or multinucleated, with unequal nuclei termed as mother nucleus and daughter nucleus. Round hemocytes were always mononucleated. The mean size of the mononucleated spreading hemocytes was 1378.42±578.08 and 1745.26±990.39 (µm)2, while that of the binucleated cells was 1843±1117 and 3202.0±1646.39 (µm)2 for P. acuta and B. bengalensis. The nucleus of spreading hemocyte was rounded to oval, kidney shaped or lobulated. Only spreading hemocytes produced filopodia and pseudopodia in almost all directions and were capable of exhibiting rapid changes in shape, but no net motion. The number of pseudopodia produced by spreading hemocytes lie between 9-27 with an average value of 17.47±5.77 and 13.79±4.89 for P. acuta and B. bengalensis respectively. Maximum average length of pseudopodia of a single spread hemocyte was 327.37±143.67µm and 226.84±95.68µm for P. acuta and B. bengalensia. The round hemocytes were characterized by the presence of more of less circular or weavy boundary, and no pseudopodia. They also posses comparatively hyaline (clear) cytoplasm alongwith few granules and vacuoles of various sizes. The mean area occupied by round hemocytes was 416.0±140.22 and 950.0±928.10 (µm)2 for P. acuta and B. bengalensis, with a typical rounded to oval nucleus. Only spreading hemocytes fuse with one another to form synctia but round hemocytes did not fuse either with each other or with spreading hemocytes. However, fusion among spreading hemocytes was reversible. The present findings are discussed in the light of available sutides on themolluscan blood in general and gastropod hemolymph in particular.

31-41

Authors: Fouzia Qamar, Firdausia Azam Ali and Shahid Husnain

Agrobacterium tumefaciens was isolated from two sources. One source was the young and freshly cut tumors from trees of Populus sp. present along the canal near the vicinity of Quaid-e-Azam Campus, Punjab University, Lahore. The other source was from stink bugs which were always found to be present in the proximity of the tumors of these trees. These insects habitually feed on them. Total of eight isolates were obtained and designated as F3O, F3W, F3y1, F3y2(1), BS, BSc and BSy. First five were obtained from the tumors and later three were isolated from hemolymph of stink bug. Two of these strains i.e., F3O and BSy were selected for inoculation studies. These were injected as well as fed in measured dozes to the insects. The effects were observed after 5 hrs, as bacteria-treated insects started showing high rate of mortality after 8 hrs. they insects which received bacteria by means of feeding survived for comparatively longer duration. Blood smear preparations of inoculated insects showed as disturbed hemocyte structure. Histological studies of the gut of bacteria-fed insects revealed a significant decrease in the length of the cells of centeric epithelium. Their total body protein content also showed a significant increase over that of the controls, but no significant increase was noted in two case of inoculated insects.