Bikonta

DOMAIN EUKARYA

  • Eukarya is a complex domain of life characterized by organisms with eukaryotic cells.

  • Major lineages classified under Domain Eukarya include:

    • Bikonta

    • Stramenopila

    • Alveolata

    • Rhizaria

    • Plantae

    • Excavata

    • Opisthokonta

    • Amoebozoa

BIKONTA LINEAGES OF DOMAIN EUKARYA

Major Lineages

EXCAVATA

  • Feeding Groove:

    • An ingestion point akin to a mouth.

  • Mitochondria:

    • Many species lack mitochondria but possess mitochondria-like genes within the nucleus.

  • Examples of Excavata:

    • Giardia (Diplomonads): causes gastrointestinal illness.

    • Euglena (Euglenids): photosynthetic and can move using flagella.

    • Trichonympha sp. (Parabasalids): symbiotic in the guts of termites.

RHIZARIA

  • Cell Structure:

    • No cell walls present.

  • Movement:

    • Characterized by thread-like pseudopodia used for locomotion.

  • Shelly Organisms:

    • Foraminiferans:

    • Have shells made of calcium carbonate.

    • Radiolarians:

    • Possess silica-based shell structures.

ALVEOLATA

  • Structural Characteristics:

    • Contains alveoli: Flattened, membrane-bound vesicles located just under the plasma membrane providing cell support.

  • Diversity:

    • Unicellular and exhibit a diverse range of morphologies and lifestyles.

  • Bioluminescence:

    • Some species are capable of bioluminescence through enzyme-catalyzed reactions.

  • Nutritional Modes:

    • Exhibit a mix of photosynthetic and heterotrophic feeding.

  • Examples of Alveolata:

    • Dinoflagellates: Unicellular with features that create red tides.

    • Ciliates: Include organisms like paramecium.

    • Other diseases associated with this group include malaria and toxoplasmosis.

STRAMENOPILA

  • Photosynthetic Capability:

    • Primarily photosynthetic organisms.

  • Life Cycle Features:

    • At some point, possess two flagella, one of which is covered with distinctive hollow hairs.

  • Examples of Stramenopila:

    • Diatoms:

    • Have a rich diversity of shapes, contributing significantly to carbon fixation.

    • Brown Algae (Kelp):

    • Multicellular forms that serve as important ecosystem components.

STRAMENOPILA, ALVEOLATA, RHIZARIA COMPARISON

  • Flagella:

    • Stramenopila and some other lineages exhibit flagella with hair-like projections.

  • Alveoli:

    • Present in Alveolata for cellular support.

  • Cell Walls:

    • Not present in Rhizaria, facilitating movement with pseudopodia.

  • Feeding Groove:

    • Observed in Excavata, essential for nutrient uptake.

  • Loss of Mitochondria:

    • Characteristic of certain lineages especially in Excavata.

DISEASES CAUSED BY EUKARYOTIC SPECIES

  • Eukaryotic diseases are often more challenging to treat as eukaryotic cells are similar to human cells, leading to more severe side effects from medication.

  • Major parasitic lineages include Alveolata and Excavata.

TOXOPLASMOSIS (Toxoplasma gondii)

  • Classification: Alveolata.

  • Hosts: Cats serve as the definitive hosts, while humans are infected via contaminated food and cat feces.

  • Risks: Major risks are for unborn children and immunocompromised individuals.

RED TIDES

  • Cause: Overgrowth of dinoflagellates in the Alveolata group.

  • Consequences:

    • Depletion of dissolved oxygen, leading to the death of marine life.

    • Production of neurotoxins that can contaminate shellfish.

MALARIA AND ITS LIFE CYCLE

  • Malaria Transmission:

    • Caused by the Plasmodium species; transmitted via mosquito bites.

  • Life Cycle Phases:

    • Involves both haploid (n) and diploid (2n) reproductive stages.

    • Mosquito bites release Plasmodium into the human bloodstream, leading to infection in the liver and blood.

MALARIA & SICKLE-CELL TRAIT

  • Geographic Distribution:

    • Higher prevalence of sickle-cell trait in regions where malaria is endemic, providing some level of protection against the disease.

  • Correlation between Alleles and Malaria:

    • HbS allele frequency varies across regions, influencing susceptibility to malaria.

EXAMPLES OF EXCAVATA DISEASES

GIARDIA

  • Pathogen: Giardia species.

  • Habitat: Commonly found in freshwater, particularly at high altitudes.

  • Symptoms: Causes significant gastrointestinal disturbances.

NAEGLERIA FOWLERI (BRAIN EATING AMOEBA)

  • Classification: Excavata.

  • Danger: Not harmful if ingested, but fatal if it enters through the nasal cavity, leading to severe brain infection.

  • Statistics: 142 reported cases in the U.S. since 1962 with only four survivors.

AFRICAN SLEEPING SICKNESS

  • Pathogen: Caused by Trypanosoma species.

  • Transmission: Spread via tsetse fly bites.

  • Stages:

    • Early: Fever, headaches, and joint pain.

    • Later: Progression to neurological symptoms, coma, and potential death.

CHAGAS DISEASE

  • Pathogen: Caused by Trypanosoma cruzi (part of Excavata).

  • Transmission: Spread by kissing bugs.

  • Symptoms: Initial flu-like symptoms followed by potential chronic phase affecting the heart.

  • Expansion: Now endemic in California and Southern U.S.

LEISHMANIASIS

  • Pathogen: Leishmania species (Excavata).

  • Transmission: Spread through bites from sandflies.

  • Types:

    • 1. Cutaneous (affecting skin)

    • 2. Visceral (affecting organs such as the liver)

    • 3. Mucocutaneous (affecting skin and mucous membranes).

INDIGENOUS CULTURES AND LEISHMANIASIS

  • Discussion on the impact of Leishmaniasis on indigenous populations in Central and South America.