Drain Tuna. Sprinkle gelatin over water in small bowl and let soften a few minutes. In small saucepan, over medium heat, heat tomato sauce until boiling. Reduce heat to low and stir in gelatin mixture. Heat, stirring, for 1 minute. In blender container, combine tuna, cottage cheese, mayonnaise, sweetner and salt and pepper. Add tomato sauce mixture and blend until smooth. Stir in celery and onions. Pour into 3 cup mold and chill unti firm. Unmold to serve. Each Serving: 130 Calories, 15g Protein, 4g Fat, 7g Carbohydrates, 731g Sodium, 22mg Cholesterol.